PYLINT(1)

NAME
pylint - Pylint Documentation

Pylint is a tool that checks for errors in Python code, tries to enforce a coding standard and looks for code smells. It can also look for certain type errors, it can recommend suggestions about how particular blocks can be refactored and can offer you details about the code's complexity.

INTRODUCTION

  What is Pylint?

Pylint is a tool that checks for errors in Python code, tries to enforce a coding standard and looks for code smells. It can also look for certain type errors, it can recommend suggestions about how particular blocks can be refactored and can offer you details about the code's complexity.

Other similar projects would include pychecker (now defunct), pyflakes, flake8, and mypy. The default coding style used by Pylint is close to PEP 8.

Pylint will display a number of messages as it analyzes the code and it can also be used for displaying some statistics about the number of warnings and errors found in different files. The messages are classified under various categories such as errors and warnings.

Last but not least, the code is given an overall mark, based on the number and severity of the warnings and errors.

  What Pylint is not?

What Pylint says is not to be taken as gospel and Pylint isn't smarter than you are: it may warn you about things that you have conscientiously done.

Pylint tries hard to report as few false positives as possible for errors, but it may be too verbose with warnings. That's for example because it tries to detect things that may be dangerous in a context, but are not in others, or because it checks for some things that you don't care about. Generally, you shouldn't expect Pylint to be totally quiet about your code, so don't necessarily be alarmed if it gives you a hell lot of messages for your project!

The best way to tackle pylint's verboseness is to:

•   enable or disable the messages or message categories that you want to be activated or not for when pylint is analyzing your code. This can be done easily through a command line flag. For instance, disabling all convention messages is simple as a --disable=C option added to pylint command.

•   create a custom configuration file, tailored to your needs. You can generate one using pylint's command --generate-rcfile.

TUTORIAL

Author
    Robert Kirkpatrick

  Intro

Beginner to coding standards? Pylint can be your guide to reveal what's really going on behind the scenes and help you to become a more aware programmer.

Sharing code is a rewarding endeavor. Putting your code out there can be either an act of philanthropy, coming of age, or a basic extension of belief in open source. Whatever the motivation, your good intentions may not have the desired outcome if people find your code hard to use or understand. The Python community has formalized some recommended programming styles to help everyone write code in a common, agreed-upon style that makes the most sense for shared code. This style is captured in PEP 8, the "Style Guide for Python Code". Pylint can be a quick and easy way of seeing if your code has captured the essence of PEP 8 and is therefore friendly to other potential users.

Perhaps you're not ready to share your code but you'd like to learn a bit more about writing better code and don't know where to start. Pylint can tell you where you may have run astray and point you in the direction to figure out what you have done and how to do better.

This tutorial is all about approaching coding standards with little or no knowledge of in-depth programming or the code standards themselves. It's the equivalent of skipping the manual and jumping right in.

My command line prompt for these examples is:

robertk01 Desktop$

  Getting Started

Running Pylint with no arguments will invoke the help dialogue and give you an idea of the arguments available to you. Do that now, i.e.:

robertk01 Desktop$ pylint
...
a bunch of stuff
...

A couple of the options that we'll focus on here are:

Commands:
  --help-msg=<msg-id>
  --generate-rcfile
Messages control:
  --disable=<msg-ids>
Reports:
  --reports=<y or n>
  --output-format=<format>

If you need more detail, you can also ask for an even longer help message, like so:

robertk01 Desktop$ pylint --long-help
...
Even more stuff
...

Pay attention to the last bit of this longer help output. This gives you a hint of what Pylint is going to pick on:

Output:
   Using the default text output, the message format is :
  MESSAGE_TYPE: LINE_NUM:[OBJECT:] MESSAGE
  There are 5 kind of message types :
  * (C) convention, for programming standard violation
  * (R) refactor, for bad code smell
  * (W) warning, for python specific problems
  * (E) error, for probable bugs in the code
  * (F) fatal, if an error occurred which prevented pylint from doing
  further processing.

When Pylint is first run on a fresh piece of code, a common complaint is that it is too noisy. The current default configuration is set to enforce all possible warnings. We'll use some of the options I noted above to make it suit your preferences a bit better (and thus make it emit messages only when needed).

  Your First Pylint'ing

We'll use a basic Python script as fodder for our tutorial. The starting code we will use is called simplecaesar.py and is here in its entirety:

#!/usr/bin/env python3
import string;
shift = 3
choice = input("would you like to encode or decode?")
word = input("Please enter text")
letters = string.ascii_letters + string.punctuation + string.digits
encoded = ''
if choice == "encode":
    for letter in word:
        if letter == ' ':
            encoded = encoded + ' '
        else:
            x = letters.index(letter) + shift
            encoded = encoded + letters[x]
if choice == "decode":
    for letter in word:
        if letter == ' ':
            encoded = encoded + ' '
        else:
            x = letters.index(letter) - shift
            encoded = encoded + letters[x]
print(encoded)

Let's get started.

If we run this:

robertk01 Desktop$ pylint simplecaesar.py
************* Module simplecaesar
simplecaesar.py:3:0: W0301: Unnecessary semicolon (unnecessary-semicolon)
simplecaesar.py:1:0: C0114: Missing module docstring (missing-module-docstring)
simplecaesar.py:5:0: C0103: Constant name "shift" doesn't conform to UPPER_CASE naming style (invalid-name)
simplecaesar.py:9:0: C0103: Constant name "encoded" doesn't conform to UPPER_CASE naming style (invalid-name)
simplecaesar.py:13:12: C0103: Constant name "encoded" doesn't conform to UPPER_CASE naming style (invalid-name)
-----------------------------------
Your code has been rated at 7.37/10

Previous experience taught me that the default output for the messages needed a bit more info. We can see the second line is:

"simplecaesar.py:1:0: C0114: Missing module docstring (missing-module-docstring)"

This basically means that line 1 violates a convention C0114. It's telling me I really should have a docstring. I agree, but what if I didn't fully understand what rule I violated. Knowing only that I violated a convention isn't much help if I'm a newbie. Another piece of information there is the message symbol between parens, missing-module-docstring here.

If I want to read up a bit more about that, I can go back to the command line and try this:

robertk01 Desktop$ pylint --help-msg=missing-module-docstring
:missing-module-docstring (C0114): *Missing module docstring*
  Used when a module has no docstring.Empty modules do not require a docstring.
  This message belongs to the basic checker.

Yeah, ok. That one was a bit of a no-brainer, but I have run into error messages that left me with no clue about what went wrong, simply because I was unfamiliar with the underlying mechanism of code theory. One error that puzzled my newbie mind was:

:too-many-instance-attributes (R0902): *Too many instance attributes (%s/%s)*

I get it now thanks to Pylint pointing it out to me. If you don't get that one, pour a fresh cup of coffee and look into it - let your programmer mind grow!

  The Next Step

Now that we got some configuration stuff out of the way, let's see what we can do with the remaining warnings.

If we add a docstring to describe what the code is meant to do that will help. There are 5 invalid-name messages that we will get to later. Lastly, I put an unnecessary semicolon at the end of the import line so I'll fix that too. To sum up, I'll add a docstring to line 2, and remove the ; from line 3.

Here is the updated code:

#!/usr/bin/env python3
"""This script prompts a user to enter a message to encode or decode
using a classic Caesar shift substitution (3 letter shift)"""
import string
shift = 3
choice = input("would you like to encode or decode?")
word = input("Please enter text")
letters = string.ascii_letters + string.punctuation + string.digits
encoded = ''
if choice == "encode":
    for letter in word:
        if letter == ' ':
            encoded = encoded + ' '
        else:
            x = letters.index(letter) + shift
            encoded = encoded + letters[x]
if choice == "decode":
    for letter in word:
        if letter == ' ':
            encoded = encoded + ' '
        else:
            x = letters.index(letter) - shift
            encoded = encoded + letters[x]
print(encoded)

Here is what happens when we run it:

robertk01 Desktop$ pylint simplecaesar.py
************* Module simplecaesar
simplecaesar.py:7:0: C0103: Constant name "shift" doesn't conform to UPPER_CASE naming style (invalid-name)
simplecaesar.py:11:0: C0103: Constant name "encoded" doesn't conform to UPPER_CASE naming style (invalid-name)
simplecaesar.py:15:12: C0103: Constant name "encoded" doesn't conform to UPPER_CASE naming style (invalid-name)
------------------------------------------------------------------
Your code has been rated at 8.42/10 (previous run: 7.37/10, +1.05)

Nice! Pylint told us how much our code rating has improved since our last run, and we're down to just the invalid-name messages.

There are fairly well defined conventions around naming things like instance variables, functions, classes, etc. The conventions focus on the use of UPPERCASE and lowercase as well as the characters that separate multiple words in the name. This lends itself well to checking via a regular expression, thus the should match (([A-Z_][A-Z1-9_]*)|(__.*__))$.

In this case Pylint is telling me that those variables appear to be constants and should be all UPPERCASE. This is an in-house convention that has lived with Pylint since its inception. You too can create your own in-house naming conventions but for the purpose of this tutorial, we want to stick to the PEP 8 standard. In this case, the variables I declared should follow the convention of all lowercase. The appropriate rule would be something like: "should match [a-z_][a-z0-9_]{2,30}$". Notice the lowercase letters in the regular expression (a-z versus A-Z).

If we run that rule using a --const-rgx='[a-z\_][a-z0-9\_]{2,30}$' option, it will now be quite quiet:

robertk01 Desktop$ pylint --const-rgx='[a-z_][a-z0-9_]{2,30}$' simplecaesar.py
-------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 8.42/10, +1.58)

Regular expressions can be quite a beast so take my word on this particular example but go ahead and read up on them if you want.

TIP: It would really be a pain to specify that regex on the command line all the time, particularly if we're using many other options. That's what a configuration file is for. We can configure our Pylint to store our options for us so we don't have to declare them on the command line. Using a configuration file is a nice way of formalizing your rules and quickly sharing them with others. Invoking pylint --generate-rcfile will create a sample rcfile with all the options set and explained in comments.

That's it for the basic intro. More tutorials will follow.

USER GUIDE

  Installation

  Python packages

Pylint should be easily installable using pip.

pip install pylint

  Source distribution installation

From the source distribution, extract the tarball, go to the extracted directory and simply run

python setup.py install

Or you can install it in editable mode, using

python setup.py develop

  Running Pylint

  Invoking Pylint

Pylint is meant to be called from the command line. The usage is

pylint [options] modules_or_packages

You should give Pylint the name of a python package or module, or some number of packages or modules. Pylint will not import this package or module, though uses Python internals to locate them and as such is subject to the same rules and configuration. You should pay attention to your PYTHONPATH, since it is a common error to analyze an installed version of a module instead of the development version.

It is also possible to analyze Python files, with a few restrictions. The thing to keep in mind is that Pylint will try to convert the file name to a module name, and only be able to process the file if it succeeds.

pylint mymodule.py

should always work since the current working directory is automatically added on top of the python path

pylint directory/mymodule.py

will work if directory is a python package (i.e. has an __init__.py file or it is an implicit namespace package) or if "directory" is in the python path.

For more details on this see the faq.

It is also possible to call Pylint from another Python program, thanks to the Run() function in the pylint.lint module (assuming Pylint options are stored in a list of strings pylint_options) as:

import pylint.lint
pylint_opts = ['--disable=line-too-long', 'myfile.py']
pylint.lint.Run(pylint_opts)

To silently run Pylint on a module_name.py module, and get its standard output and error:

from pylint import epylint as lint
(pylint_stdout, pylint_stderr) = lint.py_run('module_name.py', return_std=True)

It is also possible to include additional Pylint options in the first argument to py_run:

from pylint import epylint as lint
(pylint_stdout, pylint_stderr) = lint.py_run('module_name.py --disable C0114', return_std=True)

The options --msg-template="{path}:{line}: {category} ({msg_id}, {symbol}, {obj}) {msg}" and --reports=n are set implicitly inside the epylint module.

  Command line options

First of all, we have two basic (but useful) options.

--version
    show program's version number and exit

-h, --help
    show help about the command line options

    Pylint is architected around several checkers. You can disable a specific checker or some of its messages or message categories by specifying --disable=<symbol>. If you want to enable only some checkers or some message symbols, first use --disable=all then --enable=<symbol> with <symbol> being a comma-separated list of checker names and message symbols. See the list of available features for a description of provided checkers with their functionalities. The --disable and --enable options can be used with comma-separated lists mixing checkers, message ids and categories like -d C,W,no-error,design

    It is possible to disable all messages with --disable=all. This is useful to enable only a few checkers or a few messages by first disabling everything, and then re-enabling only what you need.

    Each checker has some specific options, which can take either a yes/no value, an integer, a python regular expression, or a comma-separated list of values (which are generally used to override a regular expression in special cases). For a full list of options, use --help

    Specifying all the options suitable for your setup and coding standards can be tedious, so it is possible to use a configuration file to specify the default values. You can specify a configuration file on the command line using the --rcfile option. Otherwise, Pylint searches for a configuration file in the following order and uses the first one it finds:

1.  pylintrc in the current working directory

2.  .pylintrc in the current working directory

3.  pyproject.toml in the current working directory, providing it has at least one tool.pylint. section. The pyproject.toml must prepend section names with tool.pylint., for example [tool.pylint.'MESSAGES CONTROL']. They can also be passed in on the command line.

4.  setup.cfg in the current working directory, providing it has at least one pylint. section

5.  If the current working directory is in a Python package, Pylint searches up the hierarchy of Python packages until it finds a pylintrc file. This allows you to specify coding standards on a module-by-module basis. Of course, a directory is judged to be a Python package if it contains an __init__.py file.

6.  The file named by environment variable PYLINTRC

7.  if you have a home directory which isn't /root:

1.  .pylintrc in your home directory

2.  .config/pylintrc in your home directory

8.  /etc/pylintrc

    The --generate-rcfile option will generate a commented configuration file on standard output according to the current configuration and exit. This includes:

•   Any configuration file found as explained above

•   Options appearing before --generate-rcfile on the Pylint command line

    Of course you can also start with the default values and hand-tune the configuration.

    Other useful global options include:

--ignore=<file[,file...]>
    Files or directories to be skipped. They should be base names, not paths.

--output-format=<format>
    Select output format (text, json, custom).

--msg-template=<template>
    Modify text output message template.

--list-msgs
    Generate pylint's messages.

--list-msgs-enabled
    Display a list of what messages are enabled and disabled with the given configuration.

--full-documentation
    Generate pylint's full documentation, in reST format.

  Parallel execution

It is possible to speed up the execution of Pylint. If the running computer has more CPUs than one, then the work for checking all files could be spread across all cores via Pylints's sub-processes. This functionality is exposed via the -j command-line parameter. If the provided number is 0, then the total number of CPUs will be autodetected and used.

Example:

pylint -j 4 mymodule1.py mymodule2.py mymodule3.py mymodule4.py

This will spawn 4 parallel Pylint sub-process, where each provided module will be checked in parallel. Discovered problems by checkers are not displayed immediately. They are shown just after checking a module is complete.

There are some limitations in running checks in parallel in the current implementation. It is not possible to use custom plugins (i.e. --load-plugins option), nor it is not possible to use initialization hooks (i.e. the --init-hook option).

  Exit codes

Pylint returns bit-encoded exit codes. If applicable, the table below lists the related stderr stream message output.
exit code | meaning | stderr stream message
0 | no error |
1 | fatal message issued |
2 | error message issued |
4 | warning message issued |
8 | refactor message issued |
16 | convention message issued |
32 | usage error | "internal error while receiving resultsfrom child linter" "Error occurred, stopping the linter." "<return of linter.help()>" "Jobs number <#> should be greater than 0" "<IOError message when trying to open output file>"

  Pylint output

  Output options

Output by default is written to stdout. The simplest way to output to a file is with the --output=<filename> option.

The default format for the output is raw text. You can change this by passing pylint the --output-format=<value> option. Possible values are: text, json, parseable, colorized and msvs (for Visual Studio).

Multiple output formats can be used at the same time by passing a comma-separated list of formats to --output-format. This output can be redirected to a file by giving a filename after a colon.

For example, to save a json report to somefile.json and print a colorized report to stdout at the same time:

--output-format=json:somefile.json,colorized

Finally, it is possible to invoke pylint programmatically with a reporter initialized with a custom stream:

pylint_output = StringIO() # Custom open stream
reporter = text.TextReporter(pylint_output)
Run(["test_file.py"], reporter=reporter, do_exit=False)
print(pylint_output.getvalue()) # Retrieve and print the text report

The reporter can accept any stream object as as parameter. In this example, the stream outputs to a file:

with open("report.out", "w") as f:
  reporter = text.TextReporter(f)
  Run(["test_file.py"], reporter=reporter, do_exit=False)

This would be useful to capture pylint output in an open stream which can be passed onto another program.

  Custom message formats

You can customize the exact way information are displayed using the --msg-template=<format string> option. The format string uses the Python new format syntax and the following fields are available :

path
    relative path to the file

abspath
    absolute path to the file

line
    line number

column
    column number

end_line
    line number of the end of the node

end_column
    column number of the end of the node

module
    module name

obj object within the module (if any)

msg text of the message

msg_id
    the message code (eg. I0011)

symbol
    symbolic name of the message (eg. locally-disabled)

C   one letter indication of the message category

category
    fullname of the message category

    For example, the former (pre 1.0) default format can be obtained with:

    pylint --msg-template='{msg_id}:{line:3d},{column}: {obj}: {msg}'

    A few other examples:

•   the default format:

    {path}:{line}:{column}: {msg_id}: {msg} ({symbol})

•   Visual Studio compatible format (former 'msvs' output format):

    {path}({line}): [{msg_id}{obj}] {msg}

•   Parseable (Emacs and all, former 'parseable' output format) format:

    {path}:{line}: [{msg_id}({symbol}), {obj}] {msg}

    The --msg-template option can only be combined with text-based reporters (--output-format either unspecified or one of: parseable, colorized or msvs). If both --output-format and --msg-template are specified, the --msg-template option will take precedence over the default line format defined by the reporter class.

    If end_line or end_column are None, they will be represented as an empty string by the default TextReporter.

  Source code analysis section

For each python module, Pylint will first display a few '*' characters followed by the name of the module. Then, a number of messages with the following format:

MESSAGE_TYPE: LINE_NUM:[OBJECT:] MESSAGE

You can get another output format, useful since it's recognized by most editors or other development tools using the --output-format=parseable option.

The message type can be:

•   [I]nformational messages that Pylint emits (do not contribute to your analysis score)

•   [R]efactor for a "good practice" metric violation

•   [C]onvention for coding standard violation

•   [W]arning for stylistic problems, or minor programming issues

•   [E]rror for important programming issues (i.e. most probably bug)

•   [F]atal for errors which prevented further processing

    Sometimes the line of code which caused the error is displayed with a caret pointing to the error. This may be generalized in future versions of Pylint.

    Example (extracted from a run of Pylint on itself...):

    ************* Module pylint.checkers.format
    W: 50: Too long line (86/80)
    W:108: Operator not followed by a space
         print >>sys.stderr, 'Unable to match %r', line
                ^
    W:141: Too long line (81/80)
    W: 74:searchall: Unreachable code
    W:171:FormatChecker.process_tokens: Redefining built-in (type)
    W:150:FormatChecker.process_tokens: Too many local variables (20/15)
    W:150:FormatChecker.process_tokens: Too many branches (13/12)

  Reports section

Following the analysis message, Pylint can display a set of reports, each one focusing on a particular aspect of the project, such as number of messages by categories, modules dependencies. These features can be enabled through the --reports=y option, or its shorthand version -rn.

For instance, the metrics report displays summaries gathered from the current run.

•   the number of processed modules

•   for each module, the percentage of errors and warnings

•   the total number of errors and warnings

•   percentage of classes, functions and modules with docstrings, and a comparison from the previous run

•   percentage of classes, functions and modules with correct name (according to the coding standard), and a comparison from the previous run

•   a list of external dependencies found in the code, and where they appear

  Score section

Finally, Pylint displays a global evaluation score for the code, rated out of a maximum score of 10.0. This output can be suppressed through the --score=n option, or its shorthand version -sn.

The evaluation formula can be overridden with the --evaluation=<python_expression> option.

  Messages control

pylint has an advanced message control for its checks, offering the ability to enable / disable a message either from the command line or from the configuration file, as well as from the code itself.

For all of these controls, pylint accepts the following values:

•   a symbolic message: no-member, undefined-variable etc.

•   a numerical ID: E1101, E1102 etc.

•   The name of the group of checks. You can grab those with pylint --list-groups. For example, you can disable / enable all the checks related to type checking, with typecheck or all the checks related to variables with variables

•   Corresponding category of the checks

•   C convention related checks

•   R refactoring related checks

•   W various warnings

•   E errors, for probable bugs in the code

•   F fatal, if an error occurred which prevented pylint from doing further processing.

•   All the checks with all

  Block disables

This describes how the pragma controls operate at a code level.

The pragma controls can disable / enable:

•   All the violations on a single line

    a, b = ... # pylint: disable=unbalanced-tuple-unpacking

•   All the violations on the following line

    # pylint: disable-next=unbalanced-tuple-unpacking
    a, b = ...

•   All the violations in a single scope

    def test():
        # Disable all the no-member violations in this function
        # pylint: disable=no-member
        ...

•   All the violations in a block. For instance, each separate branch of an if statement is considered a separate block, as in the following example:

    def meth5(self):
        # pylint: disable=no-member
        # no error
        print(self.bla)
        if self.blop:
            # pylint: enable=no-member
            # enable all no-members for this block
            print(self.blip)
        else:
            # This is affected by the scope disable
            print(self.blip)
        # pylint: enable=no-member
        print(self.blip)
        if self.blop:
            # pylint: disable=no-member
            # disable all no-members for this block
            print(self.blip)
        else:
            # This emits a violation
            print(self.blip)

•   If the violation occurs on a block starting line, then it applies only to that line

    if self.blop: # pylint: disable=no-member; applies only to this line
        # Here we get an error
        print(self.blip)
    else:
        # error
        print(self.blip)

    Here's an example with all these rules in a single place:

    """pylint option block-disable"""
    __revision__ = None
    class Foo(object):
        """block-disable test"""
        def __init__(self):
            pass
        def meth1(self, arg):
            """this issues a message"""
            print(self)
        def meth2(self, arg):
            """and this one not"""
            # pylint: disable=unused-argument
            print(self\
                  + "foo")
        def meth3(self):
            """test one line disabling"""
            # no error
            print(self.bla) # pylint: disable=no-member
            # error
            print(self.blop)
        def meth4(self):
            """test re-enabling"""
            # pylint: disable=no-member
            # no error
            print(self.bla)
            print(self.blop)
            # pylint: enable=no-member
            # error
            print(self.blip)
        def meth5(self):
            """test IF sub-block re-enabling"""
            # pylint: disable=no-member
            # no error
            print(self.bla)
            if self.blop:
                # pylint: enable=no-member
                # error
                print(self.blip)
            else:
                # no error
                print(self.blip)
            # no error
            print(self.blip)
        def meth6(self):
            """test TRY/EXCEPT sub-block re-enabling"""
            # pylint: disable=no-member
            # no error
            print(self.bla)
            try:
                # pylint: enable=no-member
                # error
                print(self.blip)
            except UndefinedName: # pylint: disable=undefined-variable
                # no error
                print(self.blip)
            # no error
            print(self.blip)
        def meth7(self):
            """test one line block opening disabling"""
            if self.blop: # pylint: disable=no-member
                # error
                print(self.blip)
            else:
                # error
                print(self.blip)
            # error
            print(self.blip)
        def meth8(self):
            """test late disabling"""
            # error
            print(self.blip)
            # pylint: disable=no-member
            # no error
            print(self.bla)
            print(self.blop)
        def meth9(self):
            """test next line disabling"""
            # no error
            # pylint: disable-next=no-member
            print(self.bla)
            # error
            print(self.blop)

  Detecting useless disables

As pylint gets better and false positives are removed, disables that became useless can accumulate and clutter the code. In order to clean them you can enable the useless-suppression warning.

  Configuration

  Naming Styles

  Introduction

Pylint recognizes a number of different name types internally. With a few exceptions, the type of the name is governed by the location the assignment to a name is found in, and not the type of object assigned.
Name Type | Description
module | Module and package names, same as the file names.
const | Module-level constants, any variable defined at module level that is not bound to a class object.
class | Names in class statements, as well as names bound to class objects at module level.
function | Functions, toplevel or nested in functions or methods.
method | Methods, functions defined in class bodies. Includes static and class methods.
attr | Attributes created on class instances inside methods.
argument | Arguments to any function type, including lambdas.
variable | Local variables in function scopes.
class-attribute | Attributes defined in class bodies.
class-const | Enum constants and class variables annotated with ClassVar
inlinevar | Loop variables in list comprehensions and generator expressions.

  Default behavior

By default, Pylint will enforce PEP8-suggested names.

  Predefined Naming Styles

Pylint provides set of predefined naming styles. Those predefined naming styles may be used to adjust Pylint configuration to coding style used in linted project.

Following predefined naming styles are available:

•   snake_case

•   camelCase

•   PascalCase

•   UPPER_CASE

•   any - fake style which does not enforce any limitations

    Following options are exposed:

--module-naming-style=<style>

--const-naming-style=<style>

--class-naming-style=<style>

--function-naming-style=<style>

--method-naming-style=<style>

--attr-naming-style=<style>

--argument-naming-style=<style>

--variable-naming-style=<style>

--class-attribute-naming-style=<style>

--class-const-naming-style=<style>

--inlinevar-naming-style=<style>

  Custom regular expressions

If predefined naming styles are too limited, checker behavior may be further customized. For each name type, a separate regular expression matching valid names of this type can be defined. If any of custom regular expressions are defined, it overrides *-naming-style option value.

Regular expressions for the names are anchored at the beginning, any anchor for the end must be supplied explicitly. Any name not matching the regular expression will lead to an instance of invalid-name.

--module-rgx=<regex>

--const-rgx=<regex>

--class-rgx=<regex>

--function-rgx=<regex>

--method-rgx=<regex>

--attr-rgx=<regex>

--argument-rgx=<regex>

--variable-rgx=<regex>

--class-attribute-rgx=<regex>

--class-const-rgx=<regex>

--inlinevar-rgx=<regex>

  Multiple naming styles for custom regular expressions

Large code bases that have been worked on for multiple years often exhibit an evolution in style as well. In some cases, modules can be in the same package, but still have different naming style based on the stratum they belong to. However, intra-module consistency should still be required, to make changes inside a single file easier. For this case, Pylint supports regular expression with several named capturing group.

Rather than emitting name warnings immediately, Pylint will determine the prevalent naming style inside each module and enforce it on all names.

Consider the following (simplified) example:

pylint --function-rgx='(?:(?P<snake>[a-z_]+)|(?P<camel>[a-z]+([A-Z][a-z]*)*))$' sample.py

The regular expression defines two naming styles, snake for snake-case names, and camel for camel-case names.

In sample.py, the function name on line 1 and 7 will mark the module and enforce the match of named group snake for the remaining names in the module:

def valid_snake_case(arg):
   ...
def InvalidCamelCase(arg):
   ...
def more_valid_snake_case(arg):
 ...

Because of this, the name on line 4 will trigger an invalid-name warning, even though the name matches the given regex.

Matches named exempt or ignore can be used for non-tainting names, to prevent built-in or interface-dictated names to trigger certain naming styles.

--name-group=<name1:name2:...,...>
    Default value: empty

    Format: comma-separated groups of colon-separated names.

    This option can be used to combine name styles. For example, function:method enforces that functions and methods use the same style, and a style triggered by either name type carries over to the other. This requires that the regular expression for the combined name types use the same group names.

  Name Hints

--include-naming-hint=y|n
    Default: off

    Include a hint (regular expression used) for the correct name format with every invalid-name warning.

  Editor and IDE integration

To use Pylint with:

•   Emacs, see https://www.emacswiki.org/emacs/PythonProgrammingInEmacs#toc8,

•   Vim, see https://www.vim.org/scripts/script.php?script_id=891,

•   Visual Studio, see https://docs.microsoft.com/visualstudio/python/code-pylint,

•   Eclipse and PyDev, see https://pydev.org/manual_adv_pylint.html,

•   Komodo, see http://mateusz.loskot.net/posts/2006/01/15/running-pylint-from-komodo/,

•   gedit, see https://launchpad.net/gedit-pylint-2 or https://wiki.gnome.org/Apps/Gedit/PylintPlugin,

•   WingIDE, see https://www.wingware.com/doc/edit/pylint,

•   PyCharm, see the section below,

•   TextMate, see the section below

•   Visual Studio Code, see https://code.visualstudio.com/docs/python/linting#_pylint,

•   Jupyter Notebook, see https://github.com/nbQA-dev/nbQA,

    Pylint is integrated in:

•   Visual Studio, see the Python > Run PyLint command on a project's context menu.

•   Eric IDE, see the Project > Check menu,

•   Spyder, see the View -> Panes -> Static code analysis pane and its corresponding documentation.

•   pyscripter, see the Tool -> Tools menu.

•   Visual Studio Code, see the Preferences -> Settings menu.

  Using Pylint thru flymake in Emacs

To enable flymake for Python, insert the following into your .emacs:

;; Configure flymake for Python
(when (load "flymake" t)
  (defun flymake-pylint-init ()
    (let* ((temp-file (flymake-init-create-temp-buffer-copy
                       'flymake-create-temp-inplace))
           (local-file (file-relative-name
                        temp-file
                        (file-name-directory buffer-file-name))))
      (list "epylint" (list local-file))))
  (add-to-list 'flymake-allowed-file-name-masks
               '("\\.py\\'" flymake-pylint-init)))
;; Set as a minor mode for Python
(add-hook 'python-mode-hook '(lambda () (flymake-mode)))

Above stuff is in pylint/elisp/pylint-flymake.el, which should be automatically installed on Debian systems, in which cases you don't have to put it in your .emacs file.

Other things you may find useful to set:

;; Configure to wait a bit longer after edits before starting
(setq-default flymake-no-changes-timeout '3)
;; Keymaps to navigate to the errors
(add-hook 'python-mode-hook '(lambda () (define-key python-mode-map "\C-cn" 'flymake-goto-next-error)))
(add-hook 'python-mode-hook '(lambda () (define-key python-mode-map "\C-cp" 'flymake-goto-prev-error)))

Finally, by default flymake only displays the extra information about the error when you hover the mouse over the highlighted line. The following will use the minibuffer to display messages when you the cursor is on the line.

;; To avoid having to mouse hover for the error message, these functions make flymake error messages
;; appear in the minibuffer
(defun show-fly-err-at-point ()
  "If the cursor is sitting on a flymake error, display the message in the minibuffer"
  (require 'cl)
  (interactive)
  (let ((line-no (line-number-at-pos)))
    (dolist (elem flymake-err-info)
      (if (eq (car elem) line-no)
      (let ((err (car (second elem))))
        (message "%s" (flymake-ler-text err)))))))
(add-hook 'post-command-hook 'show-fly-err-at-point)

Alternative, if you only wish to pollute the minibuffer after an explicit flymake-goto-* then use the following instead of a post-command-hook

(defadvice flymake-goto-next-error (after display-message activate compile)
  "Display the error in the mini-buffer rather than having to mouse over it"
  (show-fly-err-at-point))
(defadvice flymake-goto-prev-error (after display-message activate compile)
  "Display the error in the mini-buffer rather than having to mouse over it"
  (show-fly-err-at-point))

  Integrate Pylint with PyCharm

Install Pylint the usual way:

pip install pylint

Remember the path at which it's installed:

which pylint

  Using pylint-pycharm plugin

1.  In PyCharm go to Preferences > Plugins > Browse repositories...

2.  Right-click on the plugin named Pylint, select Download and Install and restart PyCharm when prompted

    If the plugin is not finding the Pylint executable (e.g. is not inside the PATH environmental variable), you can specify it manually using the plugin settings:

1.  Preferences > Other Settings > Pylint or simply click the gear icon from the side bar of the Pylint tool window

2.  Type the path directly or use the Browse button to open a file selection dialog

3.  Press the Test button to check if the plugin is able to run the executable

    For more info on how to use the plugin please check the official plugin documentation.

  Using External Tools

Within PyCharm:

1.  Navigate to the preferences window

2.  Select "External Tools"

3.  Click the plus sign at the bottom of the dialog to add a new external task

4.  In the dialog, populate the following fields:

Name
    Pylint

Description
    A Python source code analyzer which looks for programming errors, helps enforcing a coding standard and sniffs for some code smells.

Synchronize files after execution
    unchecked

Program
    /path/to/pylint

Parameters
    $FilePath$

5.  Click OK

    The option to check the current file with Pylint should now be available in Tools > External Tools > Pylint.

  Integrate Pylint with TextMate

Install Pylint in the usual way:

pip install pylint

Install the Python bundle for TextMate:

1.  select TextMate > Preferences

2.  select the Bundles tab

3.  find and tick the Python bundle in the list

    You should now see it in Bundles > Python.

    In Preferences, select the Variables tab. If a TM_PYCHECKER variable is not already listed, add it, with the value pylint.

    The default keyboard shortcut to run the syntax checker is Control-Shift-V - open a .py file in Textmate, and try it.

    You should see the output in a new window: PyCheckMate 1.2 – Pylint 1.4.4

    No config file found, using default configuration

    Then all is well, and most likely Pylint will have expressed some opinions about your Python code (or will exit with 0 if your code already conforms to its expectations).

    If you receive a message: Please install PyChecker, PyFlakes, Pylint, PEP 8 or flake8 for more extensive code checking.

    That means that Pylint wasn't found, which is likely an issue with command paths - TextMate needs be looking for Pylint on the right paths.

    Check where Pylint has been installed, using which:

    $ which pylint
    /usr/local/bin/pylint

    The output will tell you where Pylint can be found; in this case, in /usr/local/bin.

1.  select TextMate > Preferences

2.  select the Variables tab

3.  find and check that a PATH variable exists, and that it contains the appropriate path (if the path to Pylint were /usr/local/bin/pylint as above, then the variable would need to contain /usr/local/bin). An actual example in this case might be $PATH:/opt/local/bin:/usr/local/bin:/usr/texbin, which includes other paths.

    ... and try running Pylint again.

  Integrate Pylint with Visual Studio Code

  Command-line arguments and configuration files

See Pylint command line arguments for general switches. Command line arguments can be used to load Pylint plugins, such as that for Django:

"python.linting.pylintArgs": ["--load-plugins", "pylint_django"]

Options can also be specified in a pylintrc or .pylintrc file in the workspace folder, as described on Pylint command line arguments.

To control which Pylint messages are shown, add the following contents to an options file:

[MESSAGES CONTROL]
# Enable the message, report, category or checker with the given id(s). You can
# either give multiple identifier separated by comma (,) or put this option
# multiple time.
#enable=
# Disable the message, report, category or checker with the given id(s). You
# can either give multiple identifier separated by comma (,) or put this option
# multiple time (only on the command line, not in the configuration file where
# it should appear only once).
#disable=

  Message category mapping

The Python extension maps Pylint message categories to VS Code categories through the following settings. If desired, change the setting to change the mapping.
Pylint category | Applicable setting (python.linting.) | VS Code category mapping
convention | pylintCategorySeverity.convention | Information
refactor | pylintCategorySeverity.refactor | Hint
warning | pylintCategorySeverity.warning | Warning
error | pylintCategorySeverity.error | Error
fatal | pylintCategorySeverity.fatal | Error

  Pre-commit integration

pylint can be used as a pre-commit hook.

Since pylint needs to import modules and dependencies to work correctly, the hook only works with a local installation of pylint (in your environment). If you installed pylint locally it can be added to .pre-commit-config.yaml as follows:

- repo: local
  hooks:
    - id: pylint
      name: pylint
      entry: pylint
      language: system
      types: [python]
      args:
        [
          "-rn", # Only display messages
          "-sn", # Don't display the score
        ]

You can use args to pass command line arguments as described in the tutorial. A hook with more arguments could look something like this:

- repo: local
  hooks:
    - id: pylint
      name: pylint
      entry: pylint
      language: system
      types: [python]
      args:
        [
          "-rn", # Only display messages
          "-sn", # Don't display the score
          "--rcfile=pylintrc", # Link to your config file
          "--load-plugins=pylint.extensions.docparams", # Load an extension
        ]

HOW TO GUIDES

  How to Write a Checker

You can find some simple examples in the distribution (custom.py , custom_raw.py and deprecation_checker.py).

There are three kinds of checkers:

•   Raw checkers, which analyse each module as a raw file stream.

•   Token checkers, which analyse a file using the list of tokens that represent the source code in the file.

•   AST checkers, which work on an AST representation of the module.

    The AST representation is provided by the astroid library. astroid adds additional information and methods over ast in the standard library, to make tree navigation and code introspection easier.

  Writing an AST Checker

Let's implement a checker to make sure that all return nodes in a function return a unique constant. Firstly we will need to fill in some required boilerplate:

import astroid
from astroid import nodes
from pylint.checkers import BaseChecker
from pylint.interfaces import IAstroidChecker
from pylint.lint import PyLinter
class UniqueReturnChecker(BaseChecker):
    __implements__ = IAstroidChecker
    name = 'unique-returns'
    priority = -1
    msgs = {
        'W0001': (
            'Returns a non-unique constant.',
            'non-unique-returns',
            'All constants returned in a function should be unique.'
        ),
    }
    options = (
        (
            'ignore-ints',
            {
                'default': False, 'type': 'yn', 'metavar' : '<y or n>',
                'help': 'Allow returning non-unique integers',
            }
        ),
    )

So far we have defined the following required components of our checker:

•

A name. The name is used to generate a special configuration
    section for the checker, when options have been provided.

•

A priority. This must be to be lower than 0. The checkers are ordered by
    the priority when run, from the most negative to the most positive.

•

A message dictionary. Each checker is being used for finding problems
    in your code, the problems being displayed to the user through messages. The message dictionary should specify what messages the checker is going to emit. It has the following format:

    msgs = {
        'message-id': (
            'displayed-message', 'message-symbol', 'message-help'
        )
    }

•   The message-id should be a 4-digit number, prefixed with a message category. There are multiple message categories, these being C, W, E, F, R, standing for Convention, Warning, Error, Fatal and Refactoring. The rest of the 5 digits should not conflict with existing checkers and they should be consistent across the checker. For instance, the first two digits should not be different across the checker.

•   The displayed-message is used for displaying the message to the user, once it is emitted.

•   The message-symbol is an alias of the message id and it can be used wherever the message id can be used.

•   The message-help is used when calling pylint --help-msg.

    We have also defined an optional component of the checker. The options list defines any user configurable options. It has the following format:

    options = (
        'option-symbol': {'argparse-like-kwarg': 'value'},
    )

•   The option-symbol is a unique name for the option. This is used on the command line and in config files. The hyphen is replaced by an underscore when used in the checker, similarly to how you would use argparse.Namespace.

    Next we'll track when we enter and leave a function.

    def __init__(self, linter: PyLinter =None) -> None:
        super(UniqueReturnChecker, self).__init__(linter)
        self._function_stack = []
    def visit_functiondef(self, node: nodes.FunctionDef) -> None:
        self._function_stack.append([])
    def leave_functiondef(self, node: nodes.FunctionDef) -> None:
        self._function_stack.pop()

    In the constructor we initialise a stack to keep a list of return nodes for each function. An AST checker is a visitor, and should implement visit_<lowered class name> or leave_<lowered class name> methods for the nodes it's interested in. In this case we have implemented visit_functiondef and leave_functiondef to add a new list of return nodes for this function, and to remove the list of return nodes when we leave the function.

    Finally we'll implement the check. We will define a visit_return function, which is called with an astroid.nodes.Return node.

    We'll need to be able to figure out what attributes a astroid.nodes.Return node has available. We can use astroid.extract_node() for this:

    >>> node = astroid.extract_node("return 5")
    >>> node
    <Return l.1 at 0x7efe62196390>
    >>> help(node)
    >>> node.value
    <Const.int l.1 at 0x7efe62196ef0>

    We could also construct a more complete example:

    >>> node_a, node_b = astroid.extract_node("""
    ... def test():
    ...     if True:
    ...         return 5 #@
    ...     return 5 #@
    """)
    >>> node_a.value
    <Const.int l.4 at 0x7efe621a74e0>
    >>> node_a.value.value
    5
    >>> node_a.value.value == node_b.value.value
    True

    For astroid.extract_node(), you can use #@ at the end of a line to choose which statements will be extracted into nodes.

    For more information on astroid.extract_node(), see the astroid documentation.

    Now we know how to use the astroid node, we can implement our check.

    def visit_return(self, node: nodes.Return) -> None:
        if not isinstance(node.value, nodes.Const):
            return
        for other_return in self._function_stack[-1]:
           if (node.value.value == other_return.value.value and
               not (self.config.ignore_ints and node.value.pytype() == int)):
               self.add_message(
                   'non-unique-returns', node=node,
               )
        self._function_stack[-1].append(node)

    Once we have established that the source code has failed our check, we use add_message() to emit our failure message.

    Finally, we need to register the checker with pylint. Add the register function to the top level of the file.

    def register(linter):
        linter.register_checker(UniqueReturnChecker(linter))

    We are now ready to debug and test our checker!

  Debugging a Checker

It is very simple to get to a point where we can use pdb. We'll need a small test case. Put the following into a Python file:

def test():
    if True:
        return 5
    return 5
def test2():
    if True:
        return 1
    return 5

After inserting pdb into our checker and installing it, we can run pylint with only our checker:

$ pylint --load-plugins=my_plugin --disable=all --enable=non-unique-returns test.py
(Pdb)

Now we can debug our checker!

NOTE: my_plugin refers to a module called my_plugin.py. This module can be made available to pylint by putting this module's parent directory in your PYTHONPATH environment variable or by adding the my_plugin.py file to the pylint/checkers directory if running from source.

  Testing a Checker

Pylint is very well suited to test driven development. You can implement the template of the checker, produce all of your test cases and check that they fail, implement the checker, then check that all of your test cases work.

Pylint provides a pylint.testutils.CheckerTestCase to make test cases very simple. We can use the example code that we used for debugging as our test cases.

import my_plugin
import pylint.testutils
class TestUniqueReturnChecker(pylint.testutils.CheckerTestCase):
    CHECKER_CLASS = my_plugin.UniqueReturnChecker
    def test_finds_non_unique_ints(self):
        func_node, return_node_a, return_node_b = astroid.extract_node("""
        def test(): #@
            if True:
                return 5 #@
            return 5 #@
        """)
        self.checker.visit_functiondef(func_node)
        self.checker.visit_return(return_node_a)
        with self.assertAddsMessages(
            pylint.testutils.MessageTest(
                msg_id='non-unique-returns',
                node=return_node_b,
            ),
        ):
            self.checker.visit_return(return_node_b)
    def test_ignores_unique_ints(self):
        func_node, return_node_a, return_node_b = astroid.extract_node("""
        def test(): #@
            if True:
                return 1 #@
            return 5 #@
        """)
        with self.assertNoMessages():
            self.checker.visit_functiondef(func_node)
            self.checker.visit_return(return_node_a)
            self.checker.visit_return(return_node_b)

Once again we are using astroid.extract_node() to construct our test cases. pylint.testutils.CheckerTestCase has created the linter and checker for us, we simply simulate a traversal of the AST tree using the nodes that we are interested in.

  How To Write a Pylint Plugin

Pylint provides support for writing two types of extensions. First, there is the concept of checkers, which can be used for finding problems in your code. Secondly, there is also the concept of transform plugin, which represents a way through which the inference and the capabilities of Pylint can be enhanced and tailored to a particular module, library of framework.

In general, a plugin is a module which should have a function register, which takes an instance of pylint.lint.PyLinter as input.

A plugin can optionally define a function, load_configuration, which takes an instance of pylint.lint.PyLinter as input. This function is called after Pylint loads configuration from configuration file and command line interface. This function should load additional plugin specific configuration to Pylint.

So a basic hello-world plugin can be implemented as:

# Inside hello_plugin.py
def register(linter):
  print('Hello world')

We can run this plugin by placing this module in the PYTHONPATH and invoking pylint as:

$ pylint -E --load-plugins hello_plugin foo.py
Hello world

We can extend hello-world plugin to ignore some specific names using load_configuration function:

# Inside hello_plugin.py
def register(linter):
  print('Hello world')
def load_configuration(linter):
  name_checker = get_checker(linter, NameChecker)
  # We consider as good names of variables Hello and World
  name_checker.config.good_names += ('Hello', 'World')
  # We ignore bin directory
  linter.config.black_list += ('bin',)

Depending if we need a transform plugin or a checker, this might not be enough. For the former, this is enough to declare the module as a plugin, but in the case of the latter, we need to register our checker with the linter object, by calling the following inside the register function:

linter.register_checker(OurChecker(linter))

For more information on writing a checker see write_a_checker.

  Transform plugins

  Why write a plugin?

Pylint is a static analysis tool and Python is a dynamically typed language. So there will be cases where Pylint cannot analyze files properly (this problem can happen in statically typed languages also if reflection or dynamic evaluation is used).

The plugins are a way to tell Pylint how to handle such cases, since only the user would know what needs to be done. They are usually operating on the AST level, by modifying or changing it in a way which can ease its understanding by Pylint.

  Example

Let us run Pylint on a module from the Python source: warnings.py and see what happens:

amitdev$ pylint -E Lib/warnings.py
E:297,36: Instance of 'WarningMessage' has no 'message' member (no-member)
E:298,36: Instance of 'WarningMessage' has no 'filename' member (no-member)
E:298,51: Instance of 'WarningMessage' has no 'lineno' member (no-member)
E:298,64: Instance of 'WarningMessage' has no 'line' member (no-member)

Did we catch a genuine error? Let's open the code and look at WarningMessage class:

class WarningMessage(object):
  """Holds the result of a single showwarning() call."""
  _WARNING_DETAILS = ("message", "category", "filename", "lineno", "file",
                      "line")
  def __init__(self, message, category, filename, lineno, file=None,
                  line=None):
    local_values = locals()
    for attr in self._WARNING_DETAILS:
      setattr(self, attr, local_values[attr])
    self._category_name = category.__name__ if category else None
  def __str__(self):
    ...

Ah, the fields (message, category etc) are not defined statically on the class. Instead they are added using setattr. Pylint would have a tough time figuring this out.

  Enter Plugin

We can write a transform plugin to tell Pylint how to analyze this properly.

One way to fix our example with a plugin would be to transform the WarningMessage class, by setting the attributes so that Pylint can see them. This can be done by registering a transform function. We can transform any node in the parsed AST like Module, Class, Function etc. In our case we need to transform a class. It can be done so:

import astroid
def register(linter):
  # Needed for registering the plugin.
  pass
def transform(cls):
  if cls.name == 'WarningMessage':
    import warnings
    for f in warnings.WarningMessage._WARNING_DETAILS:
      cls.locals[f] = [astroid.ClassDef(f, None)]
astroid.MANAGER.register_transform(astroid.ClassDef, transform)

Let's go through the plugin. First, we need to register a class transform, which is done via the register_transform function in MANAGER. It takes the node type and function as parameters. We need to change a class, so we use astroid.ClassDef. We also pass a transform function which does the actual transformation.

transform function is simple as well. If the class is WarningMessage then we add the attributes to its locals (we are not bothered about type of attributes, so setting them as class will do. But we could set them to any type we want). That's it.

Note: We don't need to do anything in the register function of the plugin since we are not modifying anything in the linter itself.

Lets run Pylint with this plugin and see:

amitdev$ pylint -E --load-plugins warning_plugin Lib/warnings.py
amitdev$

All the false positives associated with WarningMessage are now gone. This is just an example, any code transformation can be done by plugins.

See astroid/brain for real life examples of transform plugins.

TECHNICAL REFERENCE

  Startup and the Linter Class

The two main classes in pylint.lint are pylint.lint.Run and pylint.lint.PyLinter.

The pylint.lint.Run object is responsible for starting up pylint. It does some basic checking of the given command line options to find the initial hook to run, find the config file to use, and find which plugins have been specified. It can then create the master pylint.lint.PyLinter instance and initialise it with the config file and plugins that were discovered when preprocessing the command line options. Finally the pylint.lint.Run object launches any child linters for parallel jobs, and starts the linting process.

The pylint.lint.PyLinter is responsible for coordinating the linting process. It parses the configuration and provides it for the checkers and other plugins, it handles the messages emitted by the checkers, it handles the output reporting, and it launches the checkers.

  Checkers

All of the default pylint checkers exist in pylint.checkers. This is where most of pylint's brains exist. Most checkers are AST based and so use astroid. pylint.checkers.utils provides a large number of utility methods for dealing with astroid.

  Optional Pylint checkers in the extensions module

Pylint provides the following optional plugins:

•   Deprecated Builtins checker

•   Broad Try Clause checker

•   Else If Used checker

•   Code Style checker

•   Compare-To-Zero checker

•   Comparison-Placement checker

•   Confusing Elif checker

•   Consider Ternary Expression checker

•   Parameter Documentation checker

•   Docstyle checker

•   Refactoring checker

•   Compare-To-Empty-String checker

•   Consider-Using-Any-Or-All checker

•   Design checker

•   Overlap-Except checker

•   Multiple Types checker

•   Set Membership checker

•   Typing checker

•   While Used checker

    You can activate any or all of these extensions by adding a load-plugins line to the MASTER section of your .pylintrc, for example:

    load-plugins=pylint.extensions.docparams,pylint.extensions.docstyle

  Broad Try Clause checker

This checker is provided by pylint.extensions.broad_try_clause. Verbatim name of the checker is broad_try_clause.

  Broad Try Clause checker Options

max-try-statements
    Maximum number of statements allowed in a try clause

    Default: 1

  Broad Try Clause checker Messages

too-many-try-statements (W0717)
    Try clause contains too many statements.

  Code Style checker

This checker is provided by pylint.extensions.code_style. Verbatim name of the checker is code_style.

  Code Style checker Documentation

Checkers that can improve code consistency. As such they don't necessarily provide a performance benefit and are often times opinionated.

  Code Style checker Options

max-line-length-suggestions
    Max line length for which to sill emit suggestions. Used to prevent optional suggestions which would get split by a code formatter (e.g., black). Will default to the setting for max-line-length.

  Code Style checker Messages

consider-using-tuple (R6102)
    Consider using an in-place tuple instead of list Only for style consistency! Emitted where an in-place defined list can be replaced by a tuple. Due to optimizations by CPython, there is no performance benefit from it.

consider-using-namedtuple-or-dataclass (R6101)
    Consider using namedtuple or dataclass for dictionary values Emitted when dictionary values can be replaced by namedtuples or dataclass instances.

consider-using-assignment-expr (R6103)
    Use '%s' instead Emitted when an if assignment is directly followed by an if statement and both can be combined by using an assignment expression :=. Requires Python 3.8 and py-version >= 3.8.

  Compare-To-Empty-String checker

This checker is provided by pylint.extensions.emptystring. Verbatim name of the checker is compare-to-empty-string.

  Compare-To-Empty-String checker Messages

compare-to-empty-string (C1901)
    Avoid comparisons to empty string Used when Pylint detects comparison to an empty string constant.

  Compare-To-Zero checker

This checker is provided by pylint.extensions.comparetozero. Verbatim name of the checker is compare-to-zero.

  Compare-To-Zero checker Messages

compare-to-zero (C2001)
    Avoid comparisons to zero Used when Pylint detects comparison to a 0 constant.

  Comparison-Placement checker

This checker is provided by pylint.extensions.comparison_placement. Verbatim name of the checker is comparison-placement.

  Comparison-Placement checker Messages

misplaced-comparison-constant (C2201)
    Comparison should be %s Used when the constant is placed on the left side of a comparison. It is usually clearer in intent to place it in the right hand side of the comparison.

  Confusing Elif checker

This checker is provided by pylint.extensions.confusing_elif. Verbatim name of the checker is confusing_elif.

  Confusing Elif checker Messages

confusing-consecutive-elif (R5601)
    Consecutive elif with differing indentation level, consider creating a function to separate the inner elif Used when an elif statement follows right after an indented block which itself ends with if or elif. It may not be ovious if the elif statement was willingly or mistakenly unindented. Extracting the indented if statement into a separate function might avoid confusion and prevent errors.

  Consider-Using-Any-Or-All checker

This checker is provided by pylint.extensions.for_any_all. Verbatim name of the checker is consider-using-any-or-all.

  Consider-Using-Any-Or-All checker Messages

consider-using-any-or-all (C0501)
    `for` loop could be `%s` A for loop that checks for a condition and return a bool can be replaced with any or all.

  Consider Ternary Expression checker

This checker is provided by pylint.extensions.consider_ternary_expression. Verbatim name of the checker is consider_ternary_expression.

  Consider Ternary Expression checker Messages

consider-ternary-expression (W0160)
    Consider rewriting as a ternary expression Multiple assign statements spread across if/else blocks can be rewritten with a single assignment and ternary expression

  Deprecated Builtins checker

This checker is provided by pylint.extensions.bad_builtin. Verbatim name of the checker is deprecated_builtins.

  Deprecated Builtins checker Documentation

This used to be the bad-builtin core checker, but it was moved to an extension instead. It can be used for finding prohibited used builtins, such as map or filter, for which other alternatives exists.

If you want to control for what builtins the checker should warn about, you can use the bad-functions option:

$ pylint a.py --load-plugins=pylint.extensions.bad_builtin --bad-functions=apply,reduce
...

  Deprecated Builtins checker Options

bad-functions
    List of builtins function names that should not be used, separated by a comma

    Default: map,filter

  Deprecated Builtins checker Messages

bad-builtin (W0141)
    Used builtin function %s Used when a disallowed builtin function is used (see the bad-function option). Usual disallowed functions are the ones like map, or filter , where Python offers now some cleaner alternative like list comprehension.

  Design checker

This checker is provided by pylint.extensions.mccabe. Verbatim name of the checker is design.

  Design checker Documentation

You can now use this plugin for finding complexity issues in your code base.

Activate it through pylint --load-plugins=pylint.extensions.mccabe. It introduces a new warning, too-complex, which is emitted when a code block has a complexity higher than a preestablished value, which can be controlled through the max-complexity option, such as in this example:

$ cat a.py
def f10():
    """McCabe rating: 11"""
    myint = 2
    if myint == 5:
        return myint
    elif myint == 6:
        return myint
    elif myint == 7:
        return myint
    elif myint == 8:
        return myint
    elif myint == 9:
        return myint
    elif myint == 10:
        if myint == 8:
            while True:
                return True
        elif myint == 8:
            with myint:
                return 8
    else:
        if myint == 2:
            return myint
        return myint
    return myint
$ pylint a.py --load-plugins=pylint.extensions.mccabe
R:1: 'f10' is too complex. The McCabe rating is 11 (too-complex)
$ pylint a.py --load-plugins=pylint.extensions.mccabe --max-complexity=50
$

  Design checker Options

max-complexity
    McCabe complexity cyclomatic threshold

    Default: 10

  Design checker Messages

too-complex (R1260)
    %s is too complex. The McCabe rating is %d Used when a method or function is too complex based on McCabe Complexity Cyclomatic

  Docstyle checker

This checker is provided by pylint.extensions.docstyle. Verbatim name of the checker is docstyle.

  Docstyle checker Messages

bad-docstring-quotes (C0198)
    Bad docstring quotes in %s, expected """, given %s Used when a docstring does not have triple double quotes.

docstring-first-line-empty (C0199)
    First line empty in %s docstring Used when a blank line is found at the beginning of a docstring.

  Else If Used checker

This checker is provided by pylint.extensions.check_elif. Verbatim name of the checker is else_if_used.

  Else If Used checker Messages

else-if-used (R5501)
    Consider using "elif" instead of "else if" Used when an else statement is immediately followed by an if statement and does not contain statements that would be unrelated to it.

  Multiple Types checker

This checker is provided by pylint.extensions.redefined_variable_type. Verbatim name of the checker is multiple_types.

  Multiple Types checker Messages

redefined-variable-type (R0204)
    Redefinition of %s type from %s to %s Used when the type of a variable changes inside a method or a function.

  Overlap-Except checker

This checker is provided by pylint.extensions.overlapping_exceptions. Verbatim name of the checker is overlap-except.

  Overlap-Except checker Messages

overlapping-except (W0714)
    Overlapping exceptions (%s) Used when exceptions in handler overlap or are identical

  Parameter Documentation checker

This checker is provided by pylint.extensions.docparams. Verbatim name of the checker is parameter_documentation.

  Parameter Documentation checker Documentation

If you document the parameters of your functions, methods and constructors and their types systematically in your code this optional component might be useful for you. Sphinx style, Google style, and Numpy style are supported. (For some examples, see https://pypi.python.org/pypi/sphinxcontrib-napoleon .)

You can activate this checker by adding the line:

load-plugins=pylint.extensions.docparams

to the MASTER section of your .pylintrc.

This checker verifies that all function, method, and constructor docstrings include documentation of the

•   parameters and their types

•   return value and its type

•   exceptions raised

    and can handle docstrings in

•   Sphinx style (param, type, return, rtype, raise / except):

    def function_foo(x, y, z):
        '''function foo ...
        :param x: bla x
        :type x: int
        :param y: bla y
        :type y: float
        :param int z: bla z
        :return: sum
        :rtype: float
        :raises OSError: bla
        '''
        return x + y + z

•   or the Google style (Args:, Returns:, Raises:):

    def function_foo(x, y, z):
        '''function foo ...
        Args:
            x (int): bla x
            y (float): bla y
            z (int): bla z
        Returns:
            float: sum
        Raises:
            OSError: bla
        '''
        return x + y + z

•   or the Numpy style (Parameters, Returns, Raises):

    def function_foo(x, y, z):
        '''function foo ...
        Parameters
        ----------
        x: int
            bla x
        y: float
            bla y
        z: int
            bla z
        Returns
        -------
        float
            sum
        Raises
        ------
        OSError
            bla
        '''
        return x + y + z

    You'll be notified of missing parameter documentation but also of naming inconsistencies between the signature and the documentation which often arise when parameters are renamed automatically in the code, but not in the documentation. Note: by default docstrings of private and magic methods are not checked. To change this behaviour (for example, to also check __init__) add no-docstring-rgx=^(?!__init__$)_ to the BASIC section of your .pylintrc.

    Constructor parameters can be documented in either the class docstring or the __init__ docstring, but not both:

    class ClassFoo(object):
        '''Sphinx style docstring foo
        :param float x: bla x
        :param y: bla y
        :type y: int
        '''
        def __init__(self, x, y):
            pass
    class ClassBar(object):
        def __init__(self, x, y):
            '''Google style docstring bar
            Args:
                x (float): bla x
                y (int): bla y
            '''
            pass

    In some cases, having to document all parameters is a nuisance, for instance if many of your functions or methods just follow a common interface. To remove this burden, the checker accepts missing parameter documentation if one of the following phrases is found in the docstring:

•   For the other parameters, see

•   For the parameters, see

    (with arbitrary whitespace between the words). Please add a link to the docstring defining the interface, e.g. a superclass method, after "see":

    def callback(x, y, z):
        '''Sphinx style docstring for callback ...
        :param x: bla x
        :type x: int
        For the other parameters, see
        :class:`MyFrameworkUsingAndDefiningCallback`
        '''
        return x + y + z
    def callback(x, y, z):
        '''Google style docstring for callback ...
        Args:
            x (int): bla x
        For the other parameters, see
        :class:`MyFrameworkUsingAndDefiningCallback`
        '''
        return x + y + z

    Naming inconsistencies in existing parameter and their type documentations are still detected.

  Parameter Documentation checker Options

accept-no-param-doc
    Whether to accept totally missing parameter documentation in the docstring of a function that has parameters.

    Default: yes

accept-no-raise-doc
    Whether to accept totally missing raises documentation in the docstring of a function that raises an exception.

    Default: yes

accept-no-return-doc
    Whether to accept totally missing return documentation in the docstring of a function that returns a statement.

    Default: yes

accept-no-yields-doc
    Whether to accept totally missing yields documentation in the docstring of a generator.

    Default: yes

default-docstring-type
    If the docstring type cannot be guessed the specified docstring type will be used.

    Default: default

  Parameter Documentation checker Messages

differing-param-doc (W9017)
    "%s" differing in parameter documentation Please check parameter names in declarations.

differing-type-doc (W9018)
    "%s" differing in parameter type documentation Please check parameter names in type declarations.

multiple-constructor-doc (W9005)
    "%s" has constructor parameters documented in class and __init__ Please remove parameter declarations in the class or constructor.

missing-param-doc (W9015)
    "%s" missing in parameter documentation Please add parameter declarations for all parameters.

missing-type-doc (W9016)
    "%s" missing in parameter type documentation Please add parameter type declarations for all parameters.

missing-raises-doc (W9006)
    "%s" not documented as being raised Please document exceptions for all raised exception types.

useless-param-doc (W9019)
    "%s" useless ignored parameter documentation Please remove the ignored parameter documentation.

useless-type-doc (W9020)
    "%s" useless ignored parameter type documentation Please remove the ignored parameter type documentation.

missing-any-param-doc (W9021)
    Missing any documentation in "%s" Please add parameter and/or type documentation.

missing-return-doc (W9011)
    Missing return documentation Please add documentation about what this method returns.

missing-return-type-doc (W9012)
    Missing return type documentation Please document the type returned by this method.

missing-yield-doc (W9013)
    Missing yield documentation Please add documentation about what this generator yields.

missing-yield-type-doc (W9014)
    Missing yield type documentation Please document the type yielded by this method.

redundant-returns-doc (W9008)
    Redundant returns documentation Please remove the return/rtype documentation from this method.

redundant-yields-doc (W9010)
    Redundant yields documentation Please remove the yields documentation from this method.

  Refactoring checker

This checker is provided by pylint.extensions.empty_comment. Verbatim name of the checker is refactoring.

  Refactoring checker Messages

empty-comment (R2044)
    Line with empty comment Used when a # symbol appears on a line not followed by an actual comment

  Set Membership checker

This checker is provided by pylint.extensions.set_membership. Verbatim name of the checker is set_membership.

  Set Membership checker Messages

use-set-for-membership (R6201)
    Consider using set for membership test Membership tests are more efficient when performed on a lookup optimized datatype like sets.

  Typing checker

This checker is provided by pylint.extensions.typing. Verbatim name of the checker is typing.

  Typing checker Documentation

Find issue specifically related to type annotations.

  Typing checker Options

runtime-typing
    Set to no if the app / library does NOT need to support runtime introspection of type annotations. If you use type annotations exclusively for type checking of an application, you're probably fine. For libraries, evaluate if some users what to access the type hints at runtime first, e.g., through typing.get_type_hints. Applies to Python versions 3.7 - 3.9

    Default: yes

  Typing checker Messages

deprecated-typing-alias (W6001)
    '%s' is deprecated, use '%s' instead Emitted when a deprecated typing alias is used.

consider-using-alias (R6002)
    '%s' will be deprecated with PY39, consider using '%s' instead%s Only emitted if 'runtime-typing=no' and a deprecated typing alias is used in a type annotation context in Python 3.7 or 3.8.

consider-alternative-union-syntax (R6003)
    Consider using alternative Union syntax instead of '%s'%s Emitted when 'typing.Union' or 'typing.Optional' is used instead of the alternative Union syntax 'int | None'.

  While Used checker

This checker is provided by pylint.extensions.while_used. Verbatim name of the checker is while_used.

  While Used checker Messages

while-used (W0149)
    Used `while` loop Unbounded while loops can often be rewritten as bounded for loops.

  Pylint features

  Pylint global options and switches

Pylint provides global options and switches.

  General options

ignore
    Files or directories to be skipped. They should be base names, not paths.

    Default: CVS

ignore-patterns
    Files or directories matching the regex patterns are skipped. The regex matches against base names, not paths.

ignore-paths
    Add files or directories matching the regex patterns to the ignore-list. The regex matches against paths and can be in Posix or Windows format.

persistent
    Pickle collected data for later comparisons.

    Default: yes

load-plugins
    List of plugins (as comma separated values of python module names) to load, usually to register additional checkers.

fail-under
    Specify a score threshold to be exceeded before program exits with error.

    Default: 10.0

fail-on
    Return non-zero exit code if any of these messages/categories are detected, even if score is above --fail-under value. Syntax same as enable. Messages specified are enabled, while categories only check already-enabled messages.

jobs
    Use multiple processes to speed up Pylint. Specifying 0 will auto-detect the number of processors available to use.

    Default: 1

unsafe-load-any-extension
    Allow loading of arbitrary C extensions. Extensions are imported into the active Python interpreter and may run arbitrary code.

limit-inference-results
    Control the amount of potential inferred values when inferring a single object. This can help the performance when dealing with large functions or complex, nested conditions.

    Default: 100

extension-pkg-allow-list
    A comma-separated list of package or module names from where C extensions may be loaded. Extensions are loading into the active Python interpreter and may run arbitrary code.

extension-pkg-whitelist
    A comma-separated list of package or module names from where C extensions may be loaded. Extensions are loading into the active Python interpreter and may run arbitrary code. (This is an alternative name to extension-pkg-allow-list for backward compatibility.)

suggestion-mode
    When enabled, pylint would attempt to guess common misconfiguration and emit user-friendly hints instead of false-positive error messages.

    Default: yes

exit-zero
    Always return a 0 (non-error) status code, even if lint errors are found. This is primarily useful in continuous integration scripts.

from-stdin
    Interpret the stdin as a python script, whose filename needs to be passed as the module_or_package argument.

py-version
    Minimum Python version to use for version dependent checks. Will default to the version used to run pylint.

  Messages control options

confidence
    Only show warnings with the listed confidence levels. Leave empty to show all. Valid levels: HIGH, INFERENCE, INFERENCE_FAILURE, UNDEFINED.

enable
    Enable the message, report, category or checker with the given id(s). You can either give multiple identifier separated by comma (,) or put this option multiple time (only on the command line, not in the configuration file where it should appear only once). See also the "--disable" option for examples.

disable
    Disable the message, report, category or checker with the given id(s). You can either give multiple identifiers separated by comma (,) or put this option multiple times (only on the command line, not in the configuration file where it should appear only once). You can also use "--disable=all" to disable everything first and then reenable specific checks. For example, if you want to run only the similarities checker, you can use "--disable=all --enable=similarities". If you want to run only the classes checker, but have no Warning level messages displayed, use "--disable=all --enable=classes --disable=W".

  Reports options

output-format
    Set the output format. Available formats are text, parseable, colorized, json and msvs (visual studio). You can also give a reporter class, e.g. mypackage.mymodule.MyReporterClass.

    Default: text

reports
    Tells whether to display a full report or only the messages.

evaluation
    Python expression which should return a score less than or equal to 10. You have access to the variables 'error', 'warning', 'refactor', and 'convention' which contain the number of messages in each category, as well as 'statement' which is the total number of statements analyzed. This score is used by the global evaluation report (RP0004).

    Default: 10.0 - ((float(5 * error + warning + refactor + convention) / statement) * 10)

score
    Activate the evaluation score.

    Default: yes

msg-template
    Template used to display messages. This is a python new-style format string used to format the message information. See doc for all details.

  Pylint checkers' options and switches

Pylint checkers can provide three set of features:

•   options that control their execution,

•   messages that they can raise,

•   reports that they can generate.

    Below is a list of all checkers and their features.

  Async checker

Verbatim name of the checker is async.

  Async checker Messages

not-async-context-manager (E1701)
    Async context manager '%s' doesn't implement __aenter__ and __aexit__. Used when an async context manager is used with an object that does not implement the async context management protocol. This message can't be emitted when using Python < 3.5.

yield-inside-async-function (E1700)
    Yield inside async function Used when an yield or yield from statement is found inside an async function. This message can't be emitted when using Python < 3.5.

  Basic checker

Verbatim name of the checker is basic.

  Basic checker Options

good-names
    Good variable names which should always be accepted, separated by a comma.

    Default: i,j,k,ex,Run,_

good-names-rgxs
    Good variable names regexes, separated by a comma. If names match any regex, they will always be accepted

bad-names
    Bad variable names which should always be refused, separated by a comma.

    Default: foo,bar,baz,toto,tutu,tata

bad-names-rgxs
    Bad variable names regexes, separated by a comma. If names match any regex, they will always be refused

name-group
    Colon-delimited sets of names that determine each other's naming style when the name regexes allow several styles.

include-naming-hint
    Include a hint for the correct naming format with invalid-name.

property-classes
    List of decorators that produce properties, such as abc.abstractproperty. Add to this list to register other decorators that produce valid properties. These decorators are taken in consideration only for invalid-name.

    Default: abc.abstractproperty

argument-naming-style
    Naming style matching correct argument names.

    Default: snake_case

argument-rgx
    Regular expression matching correct argument names. Overrides argument- naming-style.

attr-naming-style
    Naming style matching correct attribute names.

    Default: snake_case

attr-rgx
    Regular expression matching correct attribute names. Overrides attr-naming- style.

class-naming-style
    Naming style matching correct class names.

    Default: PascalCase

class-rgx
    Regular expression matching correct class names. Overrides class-naming- style.

class-attribute-naming-style
    Naming style matching correct class attribute names.

    Default: any

class-attribute-rgx
    Regular expression matching correct class attribute names. Overrides class- attribute-naming-style.

class-const-naming-style
    Naming style matching correct class constant names.

    Default: UPPER_CASE

class-const-rgx
    Regular expression matching correct class constant names. Overrides class- const-naming-style.

const-naming-style
    Naming style matching correct constant names.

    Default: UPPER_CASE

const-rgx
    Regular expression matching correct constant names. Overrides const-naming- style.

function-naming-style
    Naming style matching correct function names.

    Default: snake_case

function-rgx
    Regular expression matching correct function names. Overrides function- naming-style.

inlinevar-naming-style
    Naming style matching correct inline iteration names.

    Default: any

inlinevar-rgx
    Regular expression matching correct inline iteration names. Overrides inlinevar-naming-style.

method-naming-style
    Naming style matching correct method names.

    Default: snake_case

method-rgx
    Regular expression matching correct method names. Overrides method-naming- style.

module-naming-style
    Naming style matching correct module names.

    Default: snake_case

module-rgx
    Regular expression matching correct module names. Overrides module-naming- style.

variable-naming-style
    Naming style matching correct variable names.

    Default: snake_case

variable-rgx
    Regular expression matching correct variable names. Overrides variable- naming-style.

no-docstring-rgx
    Regular expression which should only match function or class names that do not require a docstring.

    Default: ^_

docstring-min-length
    Minimum line length for functions/classes that require docstrings, shorter ones are exempt.

    Default: -1

  Basic checker Messages

not-in-loop (E0103)
    %r not properly in loop Used when break or continue keywords are used outside a loop.

function-redefined (E0102)
    %s already defined line %s Used when a function / class / method is redefined.

continue-in-finally (E0116)
    'continue' not supported inside 'finally' clause Emitted when the continue keyword is found inside a finally clause, which is a SyntaxError. This message can't be emitted when using Python >= 3.8.

abstract-class-instantiated (E0110)
    Abstract class %r with abstract methods instantiated Used when an abstract class with abc.ABCMeta as metaclass has abstract methods and is instantiated.

star-needs-assignment-target (E0114)
    Can use starred expression only in assignment target Emitted when a star expression is not used in an assignment target.

duplicate-argument-name (E0108)
    Duplicate argument name %s in function definition Duplicate argument names in function definitions are syntax errors.

return-in-init (E0101)
    Explicit return in __init__ Used when the special class method __init__ has an explicit return value.

too-many-star-expressions (E0112)
    More than one starred expression in assignment Emitted when there are more than one starred expressions (*x) in an assignment. This is a SyntaxError.

nonlocal-and-global (E0115)
    Name %r is nonlocal and global Emitted when a name is both nonlocal and global.

used-prior-global-declaration (E0118)
    Name %r is used prior to global declaration Emitted when a name is used prior a global declaration, which results in an error since Python 3.6. This message can't be emitted when using Python < 3.6.

return-outside-function (E0104)
    Return outside function Used when a "return" statement is found outside a function or method.

return-arg-in-generator (E0106)
    Return with argument inside generator Used when a "return" statement with an argument is found outside in a generator function or method (e.g. with some "yield" statements). This message can't be emitted when using Python >= 3.3.

invalid-star-assignment-target (E0113)
    Starred assignment target must be in a list or tuple Emitted when a star expression is used as a starred assignment target.

bad-reversed-sequence (E0111)
    The first reversed() argument is not a sequence Used when the first argument to reversed() builtin isn't a sequence (does not implement __reversed__, nor __getitem__ and __len__

nonexistent-operator (E0107)
    Use of the non-existent %s operator Used when you attempt to use the C-style pre-increment or pre-decrement operator -- and ++, which doesn't exist in Python.

yield-outside-function (E0105)
    Yield outside function Used when a "yield" statement is found outside a function or method.

init-is-generator (E0100)
    __init__ method is a generator Used when the special class method __init__ is turned into a generator by a yield in its body.

misplaced-format-function (E0119)
    format function is not called on str Emitted when format function is not called on str object. e.g doing print("value: {}").format(123) instead of print("value: {}".format(123)). This might not be what the user intended to do.

nonlocal-without-binding (E0117)
    nonlocal name %s found without binding Emitted when a nonlocal variable does not have an attached name somewhere in the parent scopes

lost-exception (W0150)
    %s statement in finally block may swallow exception Used when a break or a return statement is found inside the finally clause of a try...finally block: the exceptions raised in the try clause will be silently swallowed instead of being re-raised.

assert-on-tuple (W0199)
    Assert called on a 2-item-tuple. Did you mean 'assert x,y'? A call of assert on a tuple will always evaluate to true if the tuple is not empty, and will always evaluate to false if it is.

assert-on-string-literal (W0129)
    Assert statement has a string literal as its first argument. The assert will %s fail. Used when an assert statement has a string literal as its first argument, which will cause the assert to always pass.

self-assigning-variable (W0127)
    Assigning the same variable %r to itself Emitted when we detect that a variable is assigned to itself

comparison-with-callable (W0143)
    Comparing against a callable, did you omit the parenthesis? This message is emitted when pylint detects that a comparison with a callable was made, which might suggest that some parenthesis were omitted, resulting in potential unwanted behaviour.

nan-comparison (W0177)
    Comparison %s should be %s Used when an expression is compared to NaNvalues like numpy.NaN and float('nan')

dangerous-default-value (W0102)
    Dangerous default value %s as argument Used when a mutable value as list or dictionary is detected in a default value for an argument.

duplicate-key (W0109)
    Duplicate key %r in dictionary Used when a dictionary expression binds the same key multiple times.

useless-else-on-loop (W0120)
    Else clause on loop without a break statement Loops should only have an else clause if they can exit early with a break statement, otherwise the statements under else should be on the same scope as the loop itself.

expression-not-assigned (W0106)
    Expression "%s" is assigned to nothing Used when an expression that is not a function call is assigned to nothing. Probably something else was intended.

confusing-with-statement (W0124)
    Following "as" with another context manager looks like a tuple. Emitted when a with statement component returns multiple values and uses name binding with as only for a part of those values, as in with ctx() as a, b. This can be misleading, since it's not clear if the context manager returns a tuple or if the node without a name binding is another context manager.

unnecessary-lambda (W0108)
    Lambda may not be necessary Used when the body of a lambda expression is a function call on the same argument list as the lambda itself; such lambda expressions are in all but a few cases replaceable with the function being called in the body of the lambda.

assign-to-new-keyword (W0111)
    Name %s will become a keyword in Python %s Used when assignment will become invalid in future Python release due to introducing new keyword.

redeclared-assigned-name (W0128)
    Redeclared variable %r in assignment Emitted when we detect that a variable was redeclared in the same assignment.

pointless-statement (W0104)
    Statement seems to have no effect Used when a statement doesn't have (or at least seems to) any effect.

pointless-string-statement (W0105)
    String statement has no effect Used when a string is used as a statement (which of course has no effect). This is a particular case of W0104 with its own message so you can easily disable it if you're using those strings as documentation, instead of comments.

unnecessary-pass (W0107)
    Unnecessary pass statement Used when a "pass" statement that can be avoided is encountered.

unreachable (W0101)
    Unreachable code Used when there is some code behind a "return" or "raise" statement, which will never be accessed.

eval-used (W0123)
    Use of eval Used when you use the "eval" function, to discourage its usage. Consider using ast.literal_eval for safely evaluating strings containing Python expressions from untrusted sources.

exec-used (W0122)
    Use of exec Used when you use the "exec" statement (function for Python 3), to discourage its usage. That doesn't mean you cannot use it !

using-constant-test (W0125)
    Using a conditional statement with a constant value Emitted when a conditional statement (If or ternary if) uses a constant value for its test. This might not be what the user intended to do.

missing-parentheses-for-call-in-test (W0126)
    Using a conditional statement with potentially wrong function or method call due to missing parentheses Emitted when a conditional statement (If or ternary if) seems to wrongly call a function due to missing parentheses

literal-comparison (R0123)
    Comparison to literal Used when comparing an object to a literal, which is usually what you do not want to do, since you can compare to a different literal than what was expected altogether.

comparison-with-itself (R0124)
    Redundant comparison - %s Used when something is compared against itself.

non-ascii-name (C0144)
    %s name "%s" contains a non-ASCII unicode character Used when the name contains at least one non-ASCII unicode character.

invalid-name (C0103)
    %s name "%s" doesn't conform to %s Used when the name doesn't conform to naming rules associated to its type (constant, variable, class...).

singleton-comparison (C0121)
    Comparison %s should be %s Used when an expression is compared to singleton values like True, False or None.

disallowed-name (C0104)
    Disallowed name "%s" Used when the name matches bad-names or bad-names-rgxs- (unauthorized names).

empty-docstring (C0112)
    Empty %s docstring Used when a module, function, class or method has an empty docstring (it would be too easy ;).

missing-class-docstring (C0115)
    Missing class docstring Used when a class has no docstring.Even an empty class must have a docstring.

missing-function-docstring (C0116)
    Missing function or method docstring Used when a function or method has no docstring.Some special methods like __init__ do not require a docstring.

missing-module-docstring (C0114)
    Missing module docstring Used when a module has no docstring.Empty modules do not require a docstring.

unidiomatic-typecheck (C0123)
    Use isinstance() rather than type() for a typecheck. The idiomatic way to perform an explicit typecheck in Python is to use isinstance(x, Y) rather than type(x) == Y, type(x) is Y. Though there are unusual situations where these give different results.

  Basic checker Reports

RP0101
    Statistics by type

  Classes checker

Verbatim name of the checker is classes.

  Classes checker Options

defining-attr-methods
    List of method names used to declare (i.e. assign) instance attributes.

    Default: __init__,__new__,setUp,__post_init__

valid-classmethod-first-arg
    List of valid names for the first argument in a class method.

    Default: cls

valid-metaclass-classmethod-first-arg
    List of valid names for the first argument in a metaclass class method.

    Default: cls

exclude-protected
    List of member names, which should be excluded from the protected access warning.

    Default: _asdict,_fields,_replace,_source,_make

check-protected-access-in-special-methods
    Warn about protected attribute access inside special methods

  Classes checker Messages

access-member-before-definition (E0203)
    Access to member %r before its definition line %s Used when an instance member is accessed before it's actually assigned.

method-hidden (E0202)
    An attribute defined in %s line %s hides this method Used when a class defines a method which is hidden by an instance attribute from an ancestor class or set by some client code.

assigning-non-slot (E0237)
    Assigning to attribute %r not defined in class slots Used when assigning to an attribute not defined in the class slots.

duplicate-bases (E0241)
    Duplicate bases for class %r Used when a class has duplicate bases.

inconsistent-mro (E0240)
    Inconsistent method resolution order for class %r Used when a class has an inconsistent method resolution order.

inherit-non-class (E0239)
    Inheriting %r, which is not a class. Used when a class inherits from something which is not a class.

invalid-class-object (E0243)
    Invalid __class__ object Used when an invalid object is assigned to a __class__ property. Only a class is permitted.

invalid-slots (E0238)
    Invalid __slots__ object Used when an invalid __slots__ is found in class. Only a string, an iterable or a sequence is permitted.

invalid-slots-object (E0236)
    Invalid object %r in __slots__, must contain only non empty strings Used when an invalid (non-string) object occurs in __slots__.

no-method-argument (E0211)
    Method has no argument Used when a method which should have the bound instance as first argument has no argument defined.

no-self-argument (E0213)
    Method should have "self" as first argument Used when a method has an attribute different the "self" as first argument. This is considered as an error since this is a so common convention that you shouldn't break it!

unexpected-special-method-signature (E0302)
    The special method %r expects %s param(s), %d %s given Emitted when a special method was defined with an invalid number of parameters. If it has too few or too many, it might not work at all.

class-variable-slots-conflict (E0242)
    Value %r in slots conflicts with class variable Used when a value in __slots__ conflicts with a class variable, property or method.

invalid-bool-returned (E0304)
    __bool__ does not return bool Used when a __bool__ method returns something which is not a bool

invalid-bytes-returned (E0308)
    __bytes__ does not return bytes Used when a __bytes__ method returns something which is not bytes

invalid-format-returned (E0311)
    __format__ does not return str Used when a __format__ method returns something which is not a string

invalid-getnewargs-returned (E0312)
    __getnewargs__ does not return a tuple Used when a __getnewargs__ method returns something which is not a tuple

invalid-getnewargs-ex-returned (E0313)
    __getnewargs_ex__ does not return a tuple containing (tuple, dict) Used when a __getnewargs_ex__ method returns something which is not of the form tuple(tuple, dict)

invalid-hash-returned (E0309)
    __hash__ does not return int Used when a __hash__ method returns something which is not an integer

invalid-index-returned (E0305)
    __index__ does not return int Used when an __index__ method returns something which is not an integer

non-iterator-returned (E0301)
    __iter__ returns non-iterator Used when an __iter__ method returns something which is not an iterable (i.e. has no __next__ method)

invalid-length-returned (E0303)
    __len__ does not return non-negative integer Used when a __len__ method returns something which is not a non-negative integer

invalid-length-hint-returned (E0310)
    __length_hint__ does not return non-negative integer Used when a __length_hint__ method returns something which is not a non- negative integer

invalid-repr-returned (E0306)
    __repr__ does not return str Used when a __repr__ method returns something which is not a string

invalid-str-returned (E0307)
    __str__ does not return str Used when a __str__ method returns something which is not a string

arguments-differ (W0221)
    %s %s %r method Used when a method has a different number of arguments than in the implemented interface or in an overridden method.

arguments-renamed (W0237)
    %s %s %r method Used when a method parameter has a different name than in the implemented interface or in an overridden method.

protected-access (W0212)
    Access to a protected member %s of a client class Used when a protected member (i.e. class member with a name beginning with an underscore) is access outside the class or a descendant of the class where it's defined.

attribute-defined-outside-init (W0201)
    Attribute %r defined outside __init__ Used when an instance attribute is defined outside the __init__ method.

subclassed-final-class (W0240)
    Class %r is a subclass of a class decorated with typing.final: %r Used when a class decorated with typing.final has been subclassed.

no-init (W0232)
    Class has no __init__ method Used when a class has no __init__ method, neither its parent classes.

abstract-method (W0223)
    Method %r is abstract in class %r but is not overridden Used when an abstract method (i.e. raise NotImplementedError) is not overridden in concrete class.

overridden-final-method (W0239)
    Method %r overrides a method decorated with typing.final which is defined in class %r Used when a method decorated with typing.final has been overridden.

invalid-overridden-method (W0236)
    Method %r was expected to be %r, found it instead as %r Used when we detect that a method was overridden in a way that does not match its base class which could result in potential bugs at runtime.

signature-differs (W0222)
    Signature differs from %s %r method Used when a method signature is different than in the implemented interface or in an overridden method.

bad-staticmethod-argument (W0211)
    Static method with %r as first argument Used when a static method has "self" or a value specified in valid- classmethod-first-arg option or valid-metaclass-classmethod-first-arg option as first argument.

unused-private-member (W0238)
    Unused private member `%s.%s` Emitted when a private member of a class is defined but not used.

useless-super-delegation (W0235)
    Useless super delegation in method %r Used whenever we can detect that an overridden method is useless, relying on super() delegation to do the same thing as another method from the MRO.

non-parent-init-called (W0233)
    __init__ method from a non direct base class %r is called Used when an __init__ method is called on a class which is not in the direct ancestors for the analysed class.

super-init-not-called (W0231)
    __init__ method from base class %r is not called Used when an ancestor class method has an __init__ method which is not called by a derived class.

property-with-parameters (R0206)
    Cannot have defined parameters for properties Used when we detect that a property also has parameters, which are useless, given that properties cannot be called with additional arguments.

useless-object-inheritance (R0205)
    Class %r inherits from object, can be safely removed from bases in python3 Used when a class inherit from object, which under python3 is implicit, hence can be safely removed from bases.

no-classmethod-decorator (R0202)
    Consider using a decorator instead of calling classmethod Used when a class method is defined without using the decorator syntax.

no-staticmethod-decorator (R0203)
    Consider using a decorator instead of calling staticmethod Used when a static method is defined without using the decorator syntax.

no-self-use (R0201)
    Method could be a function Used when a method doesn't use its bound instance, and so could be written as a function.

single-string-used-for-slots (C0205)
    Class __slots__ should be a non-string iterable Used when a class __slots__ is a simple string, rather than an iterable.

bad-classmethod-argument (C0202)
    Class method %s should have %s as first argument Used when a class method has a first argument named differently than the value specified in valid-classmethod-first-arg option (default to "cls"), recommended to easily differentiate them from regular instance methods.

bad-mcs-classmethod-argument (C0204)
    Metaclass class method %s should have %s as first argument Used when a metaclass class method has a first argument named differently than the value specified in valid-metaclass-classmethod-first-arg option (default to "mcs"), recommended to easily differentiate them from regular instance methods.

bad-mcs-method-argument (C0203)
    Metaclass method %s should have %s as first argument Used when a metaclass method has a first argument named differently than the value specified in valid-classmethod-first-arg option (default to "cls"), recommended to easily differentiate them from regular instance methods.

method-check-failed (F0202)
    Unable to check methods signature (%s / %s) Used when Pylint has been unable to check methods signature compatibility for an unexpected reason. Please report this kind if you don't make sense of it.

  Design checker

Verbatim name of the checker is design.

  Design checker Options

max-args
    Maximum number of arguments for function / method.

    Default: 5

max-locals
    Maximum number of locals for function / method body.

    Default: 15

max-returns
    Maximum number of return / yield for function / method body.

    Default: 6

max-branches
    Maximum number of branch for function / method body.

    Default: 12

max-statements
    Maximum number of statements in function / method body.

    Default: 50

max-parents
    Maximum number of parents for a class (see R0901).

    Default: 7

ignored-parents
    List of qualified class names to ignore when counting class parents (see R0901)

max-attributes
    Maximum number of attributes for a class (see R0902).

    Default: 7

min-public-methods
    Minimum number of public methods for a class (see R0903).

    Default: 2

max-public-methods
    Maximum number of public methods for a class (see R0904).

    Default: 20

max-bool-expr
    Maximum number of boolean expressions in an if statement (see R0916).

    Default: 5

exclude-too-few-public-methods
    List of regular expressions of class ancestor names to ignore when counting public methods (see R0903)

  Design checker Messages

too-few-public-methods (R0903)
    Too few public methods (%s/%s) Used when class has too few public methods, so be sure it's really worth it.

too-many-ancestors (R0901)
    Too many ancestors (%s/%s) Used when class has too many parent classes, try to reduce this to get a simpler (and so easier to use) class.

too-many-arguments (R0913)
    Too many arguments (%s/%s) Used when a function or method takes too many arguments.

too-many-boolean-expressions (R0916)
    Too many boolean expressions in if statement (%s/%s) Used when an if statement contains too many boolean expressions.

too-many-branches (R0912)
    Too many branches (%s/%s) Used when a function or method has too many branches, making it hard to follow.

too-many-instance-attributes (R0902)
    Too many instance attributes (%s/%s) Used when class has too many instance attributes, try to reduce this to get a simpler (and so easier to use) class.

too-many-locals (R0914)
    Too many local variables (%s/%s) Used when a function or method has too many local variables.

too-many-public-methods (R0904)
    Too many public methods (%s/%s) Used when class has too many public methods, try to reduce this to get a simpler (and so easier to use) class.

too-many-return-statements (R0911)
    Too many return statements (%s/%s) Used when a function or method has too many return statement, making it hard to follow.

too-many-statements (R0915)
    Too many statements (%s/%s) Used when a function or method has too many statements. You should then split it in smaller functions / methods.

  Exceptions checker

Verbatim name of the checker is exceptions.

  Exceptions checker Options

overgeneral-exceptions
    Exceptions that will emit a warning when being caught. Defaults to "BaseException, Exception".

    Default: BaseException,Exception

  Exceptions checker Messages

bad-except-order (E0701)
    Bad except clauses order (%s) Used when except clauses are not in the correct order (from the more specific to the more generic). If you don't fix the order, some exceptions may not be caught by the most specific handler.

catching-non-exception (E0712)
    Catching an exception which doesn't inherit from Exception: %s Used when a class which doesn't inherit from Exception is used as an exception in an except clause.

bad-exception-context (E0703)
    Exception context set to something which is not an exception, nor None Used when using the syntax "raise ... from ...", where the exception context is not an exception, nor None.

notimplemented-raised (E0711)
    NotImplemented raised - should raise NotImplementedError Used when NotImplemented is raised instead of NotImplementedError

raising-bad-type (E0702)
    Raising %s while only classes or instances are allowed Used when something which is neither a class, an instance or a string is raised (i.e. a TypeError will be raised).

raising-non-exception (E0710)
    Raising a new style class which doesn't inherit from BaseException Used when a new style class which doesn't inherit from BaseException is raised.

misplaced-bare-raise (E0704)
    The raise statement is not inside an except clause Used when a bare raise is not used inside an except clause. This generates an error, since there are no active exceptions to be reraised. An exception to this rule is represented by a bare raise inside a finally clause, which might work, as long as an exception is raised inside the try block, but it is nevertheless a code smell that must not be relied upon.

duplicate-except (W0705)
    Catching previously caught exception type %s Used when an except catches a type that was already caught by a previous handler.

broad-except (W0703)
    Catching too general exception %s Used when an except catches a too general exception, possibly burying unrelated errors.

raise-missing-from (W0707)
    Consider explicitly re-raising using the 'from' keyword Python 3's exception chaining means it shows the traceback of the current exception, but also the original exception. Not using raise from makes the traceback inaccurate, because the message implies there is a bug in the exception-handling code itself, which is a separate situation than wrapping an exception.

raising-format-tuple (W0715)
    Exception arguments suggest string formatting might be intended Used when passing multiple arguments to an exception constructor, the first of them a string literal containing what appears to be placeholders intended for formatting

binary-op-exception (W0711)
    Exception to catch is the result of a binary "%s" operation Used when the exception to catch is of the form "except A or B:". If intending to catch multiple, rewrite as "except (A, B):"

wrong-exception-operation (W0716)
    Invalid exception operation. %s Used when an operation is done against an exception, but the operation is not valid for the exception in question. Usually emitted when having binary operations between exceptions in except handlers.

bare-except (W0702)
    No exception type(s) specified Used when an except clause doesn't specify exceptions type to catch.

try-except-raise (W0706)
    The except handler raises immediately Used when an except handler uses raise as its first or only operator. This is useless because it raises back the exception immediately. Remove the raise operator or the entire try-except-raise block!

  Format checker

Verbatim name of the checker is format.

  Format checker Options

max-line-length
    Maximum number of characters on a single line.

    Default: 100

ignore-long-lines
    Regexp for a line that is allowed to be longer than the limit.

    Default: ^\s*(# )?<?https?://\S+>?$

single-line-if-stmt
    Allow the body of an if to be on the same line as the test if there is no else.

single-line-class-stmt
    Allow the body of a class to be on the same line as the declaration if body contains single statement.

max-module-lines
    Maximum number of lines in a module.

    Default: 1000

indent-string
    String used as indentation unit. This is usually " " (4 spaces) or "t" (1 tab).

    Default: ' '

indent-after-paren
    Number of spaces of indent required inside a hanging or continued line.

    Default: 4

expected-line-ending-format
    Expected format of line ending, e.g. empty (any line ending), LF or CRLF.

  Format checker Messages

bad-indentation (W0311)
    Bad indentation. Found %s %s, expected %s Used when an unexpected number of indentation's tabulations or spaces has been found.

unnecessary-semicolon (W0301)
    Unnecessary semicolon Used when a statement is ended by a semi-colon (";"), which isn't necessary (that's python, not C ;).

missing-final-newline (C0304)
    Final newline missing Used when the last line in a file is missing a newline.

line-too-long (C0301)
    Line too long (%s/%s) Used when a line is longer than a given number of characters.

mixed-line-endings (C0327)
    Mixed line endings LF and CRLF Used when there are mixed (LF and CRLF) newline signs in a file.

multiple-statements (C0321)
    More than one statement on a single line Used when more than on statement are found on the same line.

too-many-lines (C0302)
    Too many lines in module (%s/%s) Used when a module has too many lines, reducing its readability.

trailing-newlines (C0305)
    Trailing newlines Used when there are trailing blank lines in a file.

trailing-whitespace (C0303)
    Trailing whitespace Used when there is whitespace between the end of a line and the newline.

unexpected-line-ending-format (C0328)
    Unexpected line ending format. There is '%s' while it should be '%s'. Used when there is different newline than expected.

superfluous-parens (C0325)
    Unnecessary parens after %r keyword Used when a single item in parentheses follows an if, for, or other keyword.

  Imports checker

Verbatim name of the checker is imports.

  Imports checker Options

deprecated-modules
    Deprecated modules which should not be used, separated by a comma.

preferred-modules
    Couples of modules and preferred modules, separated by a comma.

import-graph
    Output a graph (.gv or any supported image format) of all (i.e. internal and external) dependencies to the given file (report RP0402 must not be disabled).

ext-import-graph
    Output a graph (.gv or any supported image format) of external dependencies to the given file (report RP0402 must not be disabled).

int-import-graph
    Output a graph (.gv or any supported image format) of internal dependencies to the given file (report RP0402 must not be disabled).

known-standard-library
    Force import order to recognize a module as part of the standard compatibility libraries.

known-third-party
    Force import order to recognize a module as part of a third party library.

    Default: enchant

allow-any-import-level
    List of modules that can be imported at any level, not just the top level one.

analyse-fallback-blocks
    Analyse import fallback blocks. This can be used to support both Python 2 and 3 compatible code, which means that the block might have code that exists only in one or another interpreter, leading to false positives when analysed.

allow-wildcard-with-all
    Allow wildcard imports from modules that define __all__.

  Imports checker Messages

relative-beyond-top-level (E0402)
    Attempted relative import beyond top-level package Used when a relative import tries to access too many levels in the current package.

import-error (E0401)
    Unable to import %s Used when pylint has been unable to import a module.

import-self (W0406)
    Module import itself Used when a module is importing itself.

preferred-module (W0407)
    Prefer importing %r instead of %r Used when a module imported has a preferred replacement module.

reimported (W0404)
    Reimport %r (imported line %s) Used when a module is reimported multiple times.

deprecated-module (W0402)
    Uses of a deprecated module %r Used a module marked as deprecated is imported.

wildcard-import (W0401)
    Wildcard import %s Used when from module import * is detected.

misplaced-future (W0410)
    __future__ import is not the first non docstring statement Python 2.5 and greater require __future__ import to be the first non docstring statement in the module.

cyclic-import (R0401)
    Cyclic import (%s) Used when a cyclic import between two or more modules is detected.

consider-using-from-import (R0402)
    Use 'from %s import %s' instead Emitted when a submodule of a package is imported and aliased with the same name. E.g., instead of import concurrent.futures as futures use from concurrent import futures

wrong-import-order (C0411)
    %s should be placed before %s Used when PEP8 import order is not respected (standard imports first, then third-party libraries, then local imports)

wrong-import-position (C0413)
    Import "%s" should be placed at the top of the module Used when code and imports are mixed

useless-import-alias (C0414)
    Import alias does not rename original package Used when an import alias is same as original package.e.g using import numpy as numpy instead of import numpy as np

import-outside-toplevel (C0415)
    Import outside toplevel (%s) Used when an import statement is used anywhere other than the module toplevel. Move this import to the top of the file.

ungrouped-imports (C0412)
    Imports from package %s are not grouped Used when imports are not grouped by packages

multiple-imports (C0410)
    Multiple imports on one line (%s) Used when import statement importing multiple modules is detected.

  Imports checker Reports

RP0401
    External dependencies

RP0402
    Modules dependencies graph

  Logging checker

Verbatim name of the checker is logging.

  Logging checker Options

logging-modules
    Logging modules to check that the string format arguments are in logging function parameter format.

    Default: logging

logging-format-style
    The type of string formatting that logging methods do. old means using % formatting, new is for {} formatting.

    Default: old

  Logging checker Messages

logging-format-truncated (E1201)
    Logging format string ends in middle of conversion specifier Used when a logging statement format string terminates before the end of a conversion specifier.

logging-too-few-args (E1206)
    Not enough arguments for logging format string Used when a logging format string is given too few arguments.

logging-too-many-args (E1205)
    Too many arguments for logging format string Used when a logging format string is given too many arguments.

logging-unsupported-format (E1200)
    Unsupported logging format character %r (%#02x) at index %d Used when an unsupported format character is used in a logging statement format string.

logging-format-interpolation (W1202)
    Use %s formatting in logging functions Used when a logging statement has a call form of "logging.<logging method>(format_string.format(format_args...))". Use another type of string formatting instead. You can use % formatting but leave interpolation to the logging function by passing the parameters as arguments. If logging-fstring- interpolation is disabled then you can use fstring formatting. If logging- not-lazy is disabled then you can use % formatting as normal.

logging-fstring-interpolation (W1203)
    Use %s formatting in logging functions Used when a logging statement has a call form of "logging.<logging method>(f"...")".Use another type of string formatting instead. You can use % formatting but leave interpolation to the logging function by passing the parameters as arguments. If logging-format-interpolation is disabled then you can use str.format. If logging-not-lazy is disabled then you can use % formatting as normal.

logging-not-lazy (W1201)
    Use %s formatting in logging functions Used when a logging statement has a call form of "logging.<logging method>(format_string % (format_args...))". Use another type of string formatting instead. You can use % formatting but leave interpolation to the logging function by passing the parameters as arguments. If logging-fstring- interpolation is disabled then you can use fstring formatting. If logging- format-interpolation is disabled then you can use str.format.

  Metrics checker

Verbatim name of the checker is metrics.

  Metrics checker Reports

RP0701
    Raw metrics

  Miscellaneous checker

Verbatim name of the checker is miscellaneous.

  Miscellaneous checker Options

notes
    List of note tags to take in consideration, separated by a comma.

    Default: FIXME,XXX,TODO

notes-rgx
    Regular expression of note tags to take in consideration.

  Miscellaneous checker Messages

fixme (W0511)
    Used when a warning note as FIXME or XXX is detected.

use-symbolic-message-instead (I0023)
    Used when a message is enabled or disabled by id.

  Newstyle checker

Verbatim name of the checker is newstyle.

  Newstyle checker Messages

bad-super-call (E1003)
    Bad first argument %r given to super() Used when another argument than the current class is given as first argument of the super builtin.

  Refactoring checker

Verbatim name of the checker is refactoring.

  Refactoring checker Options

max-nested-blocks
    Maximum number of nested blocks for function / method body

    Default: 5

never-returning-functions
    Complete name of functions that never returns. When checking for inconsistent-return-statements if a never returning function is called then it will be considered as an explicit return statement and no message will be printed.

    Default: sys.exit,argparse.parse_error

  Refactoring checker Messages

simplifiable-condition (R1726)
    Boolean condition '%s' may be simplified to '%s' Emitted when a boolean condition is able to be simplified.

condition-evals-to-constant (R1727)
    Boolean condition '%s' will always evaluate to '%s' Emitted when a boolean condition can be simplified to a constant value.

simplify-boolean-expression (R1709)
    Boolean expression may be simplified to %s Emitted when redundant pre-python 2.5 ternary syntax is used.

consider-using-in (R1714)
    Consider merging these comparisons with "in" to %r To check if a variable is equal to one of many values,combine the values into a tuple and check if the variable is contained "in" it instead of checking for equality against each of the values.This is faster and less verbose.

consider-merging-isinstance (R1701)
    Consider merging these isinstance calls to isinstance(%s, (%s)) Used when multiple consecutive isinstance calls can be merged into one.

consider-using-max-builtin (R1731)
    Consider using '%s' instead of unnecessary if block Using the max builtin instead of a conditional improves readability and conciseness.

consider-using-min-builtin (R1730)
    Consider using '%s' instead of unnecessary if block Using the min builtin instead of a conditional improves readability and conciseness.

consider-using-with (R1732)
    Consider using 'with' for resource-allocating operations Emitted if a resource-allocating assignment or call may be replaced by a 'with' block. By using 'with' the release of the allocated resources is ensured even in the case of an exception.

super-with-arguments (R1725)
    Consider using Python 3 style super() without arguments Emitted when calling the super() builtin with the current class and instance. On Python 3 these arguments are the default and they can be omitted.

use-list-literal (R1734)
    Consider using [] instead of list() Emitted when using list() to create an empty list instead of the literal []. The literal is faster as it avoids an additional function call.

consider-using-dict-comprehension (R1717)
    Consider using a dictionary comprehension Emitted when we detect the creation of a dictionary using the dict() callable and a transient list. Although there is nothing syntactically wrong with this code, it is hard to read and can be simplified to a dict comprehension.Also it is faster since you don't need to create another transient list

consider-using-generator (R1728)
    Consider using a generator instead '%s(%s)' If your container can be large using a generator will bring better performance.

consider-using-set-comprehension (R1718)
    Consider using a set comprehension Although there is nothing syntactically wrong with this code, it is hard to read and can be simplified to a set comprehension.Also it is faster since you don't need to create another transient list

consider-using-get (R1715)
    Consider using dict.get for getting values from a dict if a key is present or a default if not Using the builtin dict.get for getting a value from a dictionary if a key is present or a default if not, is simpler and considered more idiomatic, although sometimes a bit slower

consider-using-join (R1713)
    Consider using str.join(sequence) for concatenating strings from an iterable Using str.join(sequence) is faster, uses less memory and increases readability compared to for-loop iteration.

consider-using-sys-exit (R1722)
    Consider using sys.exit() Instead of using exit() or quit(), consider using the sys.exit().

consider-using-ternary (R1706)
    Consider using ternary (%s) Used when one of known pre-python 2.5 ternary syntax is used.

consider-swap-variables (R1712)
    Consider using tuple unpacking for swapping variables You do not have to use a temporary variable in order to swap variables. Using "tuple unpacking" to directly swap variables makes the intention more clear.

use-dict-literal (R1735)
    Consider using {} instead of dict() Emitted when using dict() to create an empty dictionary instead of the literal {}. The literal is faster as it avoids an additional function call.

trailing-comma-tuple (R1707)
    Disallow trailing comma tuple In Python, a tuple is actually created by the comma symbol, not by the parentheses. Unfortunately, one can actually create a tuple by misplacing a trailing comma, which can lead to potential weird bugs in your code. You should always use parentheses explicitly for creating a tuple.

stop-iteration-return (R1708)
    Do not raise StopIteration in generator, use return statement instead According to PEP479, the raise of StopIteration to end the loop of a generator may lead to hard to find bugs. This PEP specify that raise StopIteration has to be replaced by a simple return statement

inconsistent-return-statements (R1710)
    Either all return statements in a function should return an expression, or none of them should. According to PEP8, if any return statement returns an expression, any return statements where no value is returned should explicitly state this as return None, and an explicit return statement should be present at the end of the function (if reachable)

redefined-argument-from-local (R1704)
    Redefining argument with the local name %r Used when a local name is redefining an argument, which might suggest a potential error. This is taken in account only for a handful of name binding operations, such as for iteration, with statement assignment and exception handler assignment.

chained-comparison (R1716)
    Simplify chained comparison between the operands This message is emitted when pylint encounters boolean operation like"a < b and b < c", suggesting instead to refactor it to "a < b < c"

simplifiable-if-expression (R1719)
    The if expression can be replaced with %s Used when an if expression can be replaced with 'bool(test)'.

simplifiable-if-statement (R1703)
    The if statement can be replaced with %s Used when an if statement can be replaced with 'bool(test)'.

too-many-nested-blocks (R1702)
    Too many nested blocks (%s/%s) Used when a function or a method has too many nested blocks. This makes the code less understandable and maintainable.

no-else-break (R1723)
    Unnecessary "%s" after "break" Used in order to highlight an unnecessary block of code following an if containing a break statement. As such, it will warn when it encounters an else following a chain of ifs, all of them containing a break statement.

no-else-continue (R1724)
    Unnecessary "%s" after "continue" Used in order to highlight an unnecessary block of code following an if containing a continue statement. As such, it will warn when it encounters an else following a chain of ifs, all of them containing a continue statement.

no-else-raise (R1720)
    Unnecessary "%s" after "raise" Used in order to highlight an unnecessary block of code following an if containing a raise statement. As such, it will warn when it encounters an else following a chain of ifs, all of them containing a raise statement.

no-else-return (R1705)
    Unnecessary "%s" after "return" Used in order to highlight an unnecessary block of code following an if containing a return statement. As such, it will warn when it encounters an else following a chain of ifs, all of them containing a return statement.

unnecessary-dict-index-lookup (R1733)
    Unnecessary dictionary index lookup, use '%s' instead Emitted when iterating over the dictionary items (key-item pairs) and accessing the value by index lookup. The value can be accessed directly instead.

unnecessary-comprehension (R1721)
    Unnecessary use of a comprehension, use %s instead. Instead of using an identity comprehension, consider using the list, dict or set constructor. It is faster and simpler.

use-a-generator (R1729)
    Use a generator instead '%s(%s)' Comprehension inside of 'any' or 'all' is unnecessary. A generator would be sufficient and faster.

useless-return (R1711)
    Useless return at end of function or method Emitted when a single "return" or "return None" statement is found at the end of function or method definition. This statement can safely be removed because Python will implicitly return None

use-implicit-booleaness-not-comparison (C1803)
    '%s' can be simplified to '%s' as an empty sequence is falsey Used when Pylint detects that collection literal comparison is being used to check for emptiness; Use implicit booleaness insteadof a collection classes; empty collections are considered as false

unneeded-not (C0113)
    Consider changing "%s" to "%s" Used when a boolean expression contains an unneeded negation.

consider-iterating-dictionary (C0201)
    Consider iterating the dictionary directly instead of calling .keys() Emitted when the keys of a dictionary are iterated through the .keys() method or when .keys() is used for a membership check. It is enough to iterate through the dictionary itself, for key in dictionary. For membership checks, if key in dictionary is faster.

consider-using-dict-items (C0206)
    Consider iterating with .items() Emitted when iterating over the keys of a dictionary and accessing the value by index lookup. Both the key and value can be accessed by iterating using the .items() method of the dictionary instead.

consider-using-enumerate (C0200)
    Consider using enumerate instead of iterating with range and len Emitted when code that iterates with range and len is encountered. Such code can be simplified by using the enumerate builtin.

use-implicit-booleaness-not-len (C1802)
    Do not use `len(SEQUENCE)` without comparison to determine if a sequence is empty Used when Pylint detects that len(sequence) is being used without explicit comparison inside a condition to determine if a sequence is empty. Instead of coercing the length to a boolean, either rely on the fact that empty sequences are false or compare the length against a scalar.

consider-using-f-string (C0209)
    Formatting a regular string which could be a f-string Used when we detect a string that is being formatted with format() or % which could potentially be a f-string. The use of f-strings is preferred. Requires Python 3.6 and py-version >= 3.6.

use-maxsplit-arg (C0207)
    Use %s instead Emitted when accessing only the first or last element of str.split(). The first and last element can be accessed by using str.split(sep, maxsplit=1)[0] or str.rsplit(sep, maxsplit=1)[-1] instead.

use-sequence-for-iteration (C0208)
    Use a sequence type when iterating over values When iterating over values, sequence types (e.g., lists, tuples, ranges) are more efficient than sets.

  Similarities checker

Verbatim name of the checker is similarities.

  Similarities checker Options

min-similarity-lines
    Minimum lines number of a similarity.

    Default: 4

ignore-comments
    Comments are removed from the similarity computation

    Default: yes

ignore-docstrings
    Docstrings are removed from the similarity computation

    Default: yes

ignore-imports
    Imports are removed from the similarity computation

ignore-signatures
    Signatures are removed from the similarity computation

  Similarities checker Messages

duplicate-code (R0801)
    Similar lines in %s files Indicates that a set of similar lines has been detected among multiple file. This usually means that the code should be refactored to avoid this duplication.

  Similarities checker Reports

RP0801
    Duplication

  Spelling checker

Verbatim name of the checker is spelling.

  Spelling checker Options

spelling-dict
    Spelling dictionary name. Available dictionaries: none. To make it work, install the 'python-enchant' package.

spelling-ignore-words
    List of comma separated words that should not be checked.

spelling-private-dict-file
    A path to a file that contains the private dictionary; one word per line.

spelling-store-unknown-words
    Tells whether to store unknown words to the private dictionary (see the --spelling-private-dict-file option) instead of raising a message.

max-spelling-suggestions
    Limits count of emitted suggestions for spelling mistakes.

    Default: 4

spelling-ignore-comment-directives
    List of comma separated words that should be considered directives if they appear and the beginning of a comment and should not be checked.

    Default: fmt: on,fmt: off,noqa:,noqa,nosec,isort:skip,mypy:

  Spelling checker Messages

invalid-characters-in-docstring (C0403)
    Invalid characters %r in a docstring Used when a word in docstring cannot be checked by enchant.

wrong-spelling-in-comment (C0401)
    Wrong spelling of a word '%s' in a comment: Used when a word in comment is not spelled correctly.

wrong-spelling-in-docstring (C0402)
    Wrong spelling of a word '%s' in a docstring: Used when a word in docstring is not spelled correctly.

  Stdlib checker

Verbatim name of the checker is stdlib.

  Stdlib checker Messages

invalid-envvar-value (E1507)
    %s does not support %s type argument Env manipulation functions support only string type arguments. See https://docs.python.org/3/library/os.html#os.getenv.

bad-open-mode (W1501)
    "%s" is not a valid mode for open. Python supports: r, w, a[, x] modes with b, +, and U (only with r) options. See https://docs.python.org/2/library/functions.html#open

invalid-envvar-default (W1508)
    %s default type is %s. Expected str or None. Env manipulation functions return None or str values. Supplying anything different as a default may cause bugs. See https://docs.python.org/3/library/os.html#os.getenv.

forgotten-debug-statement (W1515)
    Leaving functions creating breakpoints in production code is not recommended Calls to breakpoint(), sys.breakpointhook() and pdb.set_trace() should be removed from code that is not actively being debugged.

redundant-unittest-assert (W1503)
    Redundant use of %s with constant value %r The first argument of assertTrue and assertFalse is a condition. If a constant is passed as parameter, that condition will be always true. In this case a warning should be emitted.

shallow-copy-environ (W1507)
    Using copy.copy(os.environ). Use os.environ.copy() instead. os.environ is not a dict object but proxy object, so shallow copy has still effects on original object. See https://bugs.python.org/issue15373 for reference.

boolean-datetime (W1502)
    Using datetime.time in a boolean context. Using datetime.time in a boolean context can hide subtle bugs when the time they represent matches midnight UTC. This behaviour was fixed in Python 3.5. See https://bugs.python.org/issue13936 for reference. This message can't be emitted when using Python >= 3.5.

deprecated-argument (W1511)
    Using deprecated argument %s of method %s() The argument is marked as deprecated and will be removed in the future.

deprecated-class (W1512)
    Using deprecated class %s of module %s The class is marked as deprecated and will be removed in the future.

deprecated-decorator (W1513)
    Using deprecated decorator %s() The decorator is marked as deprecated and will be removed in the future.

deprecated-method (W1505)
    Using deprecated method %s() The method is marked as deprecated and will be removed in a future version of Python. Consider looking for an alternative in the documentation.

unspecified-encoding (W1514)
    Using open without explicitly specifying an encoding It is better to specify an encoding when opening documents. Using the system default implicitly can create problems on other operating systems. See https://www.python.org/dev/peps/pep-0597/

subprocess-popen-preexec-fn (W1509)
    Using preexec_fn keyword which may be unsafe in the presence of threads The preexec_fn parameter is not safe to use in the presence of threads in your application. The child process could deadlock before exec is called. If you must use it, keep it trivial! Minimize the number of libraries you call into.https://docs.python.org/3/library/subprocess.html#popen-constructor

subprocess-run-check (W1510)
    Using subprocess.run without explicitly set `check` is not recommended. The check parameter should always be used with explicitly set check keyword to make clear what the error-handling behavior is.https://docs.python.org/3/library/subprocess.html#subprocess.run

bad-thread-instantiation (W1506)
    threading.Thread needs the target function The warning is emitted when a threading.Thread class is instantiated without the target function being passed. By default, the first parameter is the group param, not the target param.

  String checker

Verbatim name of the checker is string.

  String checker Options

check-str-concat-over-line-jumps
    This flag controls whether the implicit-str-concat should generate a warning on implicit string concatenation in sequences defined over several lines.

check-quote-consistency
    This flag controls whether inconsistent-quotes generates a warning when the character used as a quote delimiter is used inconsistently within a module.

  String checker Messages

bad-string-format-type (E1307)
    Argument %r does not match format type %r Used when a type required by format string is not suitable for actual argument type

format-needs-mapping (E1303)
    Expected mapping for format string, not %s Used when a format string that uses named conversion specifiers is used with an argument that is not a mapping.

truncated-format-string (E1301)
    Format string ends in middle of conversion specifier Used when a format string terminates before the end of a conversion specifier.

missing-format-string-key (E1304)
    Missing key %r in format string dictionary Used when a format string that uses named conversion specifiers is used with a dictionary that doesn't contain all the keys required by the format string.

mixed-format-string (E1302)
    Mixing named and unnamed conversion specifiers in format string Used when a format string contains both named (e.g. '%(foo)d') and unnamed (e.g. '%d') conversion specifiers. This is also used when a named conversion specifier contains * for the minimum field width and/or precision.

too-few-format-args (E1306)
    Not enough arguments for format string Used when a format string that uses unnamed conversion specifiers is given too few arguments

bad-str-strip-call (E1310)
    Suspicious argument in %s.%s call The argument to a str.{l,r,}strip call contains a duplicate character,

too-many-format-args (E1305)
    Too many arguments for format string Used when a format string that uses unnamed conversion specifiers is given too many arguments.

bad-format-character (E1300)
    Unsupported format character %r (%#02x) at index %d Used when an unsupported format character is used in a format string.

anomalous-unicode-escape-in-string (W1402)
    Anomalous Unicode escape in byte string: '%s'. String constant might be missing an r or u prefix. Used when an escape like u is encountered in a byte string where it has no effect.

anomalous-backslash-in-string (W1401)
    Anomalous backslash in string: '%s'. String constant might be missing an r prefix. Used when a backslash is in a literal string but not as an escape.

duplicate-string-formatting-argument (W1308)
    Duplicate string formatting argument %r, consider passing as named argument Used when we detect that a string formatting is repeating an argument instead of using named string arguments

format-combined-specification (W1305)
    Format string contains both automatic field numbering and manual field specification Used when a PEP 3101 format string contains both automatic field numbering (e.g. '{}') and manual field specification (e.g. '{0}').

bad-format-string-key (W1300)
    Format string dictionary key should be a string, not %s Used when a format string that uses named conversion specifiers is used with a dictionary whose keys are not all strings.

implicit-str-concat (W1404)
    Implicit string concatenation found in %s String literals are implicitly concatenated in a literal iterable definition : maybe a comma is missing ?

bad-format-string (W1302)
    Invalid format string Used when a PEP 3101 format string is invalid.

missing-format-attribute (W1306)
    Missing format attribute %r in format specifier %r Used when a PEP 3101 format string uses an attribute specifier ({0.length}), but the argument passed for formatting doesn't have that attribute.

missing-format-argument-key (W1303)
    Missing keyword argument %r for format string Used when a PEP 3101 format string that uses named fields doesn't receive one or more required keywords.

inconsistent-quotes (W1405)
    Quote delimiter %s is inconsistent with the rest of the file Quote delimiters are not used consistently throughout a module (with allowances made for avoiding unnecessary escaping).

redundant-u-string-prefix (W1406)
    The u prefix for strings is no longer necessary in Python >=3.0 Used when we detect a string with a u prefix. These prefixes were necessary in Python 2 to indicate a string was Unicode, but since Python 3.0 strings are Unicode by default.

unused-format-string-argument (W1304)
    Unused format argument %r Used when a PEP 3101 format string that uses named fields is used with an argument that is not required by the format string.

unused-format-string-key (W1301)
    Unused key %r in format string dictionary Used when a format string that uses named conversion specifiers is used with a dictionary that contains keys not required by the format string.

f-string-without-interpolation (W1309)
    Using an f-string that does not have any interpolated variables Used when we detect an f-string that does not use any interpolation variables, in which case it can be either a normal string or a bug in the code.

format-string-without-interpolation (W1310)
    Using formatting for a string that does not have any interpolated variables Used when we detect a string that does not have any interpolation variables, in which case it can be either a normal string without formatting or a bug in the code.

invalid-format-index (W1307)
    Using invalid lookup key %r in format specifier %r Used when a PEP 3101 format string uses a lookup specifier ({a[1]}), but the argument passed for formatting doesn't contain or doesn't have that key as an attribute.

  Threading checker

Verbatim name of the checker is threading.

  Threading checker Messages

useless-with-lock (W2101)
    '%s()' directly created in 'with' has no effect Used when a new lock instance is created by using with statement which has no effect. Instead, an existing instance should be used to acquire lock.

  Typecheck checker

Verbatim name of the checker is typecheck.

  Typecheck checker Options

ignore-on-opaque-inference
    This flag controls whether pylint should warn about no-member and similar checks whenever an opaque object is returned when inferring. The inference can return multiple potential results while evaluating a Python object, but some branches might not be evaluated, which results in partial inference. In that case, it might be useful to still emit no-member and other checks for the rest of the inferred objects.

    Default: yes

mixin-class-rgx
    Regex pattern to define which classes are considered mixins ignore-mixin- members is set to 'yes'

    Default: .*[Mm]ixin

ignore-mixin-members
    Tells whether missing members accessed in mixin class should be ignored. A class is considered mixin if its name matches the mixin-class-rgx option.

    Default: yes

ignore-none
    Tells whether to warn about missing members when the owner of the attribute is inferred to be None.

    Default: yes

ignored-modules
    List of module names for which member attributes should not be checked (useful for modules/projects where namespaces are manipulated during runtime and thus existing member attributes cannot be deduced by static analysis). It supports qualified module names, as well as Unix pattern matching.

ignored-classes
    List of class names for which member attributes should not be checked (useful for classes with dynamically set attributes). This supports the use of qualified names.

    Default: optparse.Values,thread._local,_thread._local

generated-members
    List of members which are set dynamically and missed by pylint inference system, and so shouldn't trigger E1101 when accessed. Python regular expressions are accepted.

contextmanager-decorators
    List of decorators that produce context managers, such as contextlib.contextmanager. Add to this list to register other decorators that produce valid context managers.

    Default: contextlib.contextmanager

missing-member-hint-distance
    The minimum edit distance a name should have in order to be considered a similar match for a missing member name.

    Default: 1

missing-member-max-choices
    The total number of similar names that should be taken in consideration when showing a hint for a missing member.

    Default: 1

missing-member-hint
    Show a hint with possible names when a member name was not found. The aspect of finding the hint is based on edit distance.

    Default: yes

signature-mutators
    List of decorators that change the signature of a decorated function.

  Typecheck checker Messages

unsupported-assignment-operation (E1137)
    %r does not support item assignment Emitted when an object does not support item assignment (i.e. doesn't define __setitem__ method).

unsupported-delete-operation (E1138)
    %r does not support item deletion Emitted when an object does not support item deletion (i.e. doesn't define __delitem__ method).

invalid-unary-operand-type (E1130)
    Emitted when a unary operand is used on an object which does not support this type of operation.

unsupported-binary-operation (E1131)
    Emitted when a binary arithmetic operation between two operands is not supported.

no-member (E1101)
    %s %r has no %r member%s Used when a variable is accessed for an unexistent member.

not-callable (E1102)
    %s is not callable Used when an object being called has been inferred to a non callable object.

await-outside-async (E1142)
    'await' should be used within an async function Emitted when await is used outside an async function.

redundant-keyword-arg (E1124)
    Argument %r passed by position and keyword in %s call Used when a function call would result in assigning multiple values to a function parameter, one value from a positional argument and one from a keyword argument.

assignment-from-no-return (E1111)
    Assigning result of a function call, where the function has no return Used when an assignment is done on a function call but the inferred function doesn't return anything.

assignment-from-none (E1128)
    Assigning result of a function call, where the function returns None Used when an assignment is done on a function call but the inferred function returns nothing but None.

not-context-manager (E1129)
    Context manager '%s' doesn't implement __enter__ and __exit__. Used when an instance in a with statement doesn't implement the context manager protocol(__enter__/__exit__).

unhashable-dict-key (E1140)
    Dict key is unhashable Emitted when a dict key is not hashable (i.e. doesn't define __hash__ method).

repeated-keyword (E1132)
    Got multiple values for keyword argument %r in function call Emitted when a function call got multiple values for a keyword.

invalid-metaclass (E1139)
    Invalid metaclass %r used Emitted whenever we can detect that a class is using, as a metaclass, something which might be invalid for using as a metaclass.

missing-kwoa (E1125)
    Missing mandatory keyword argument %r in %s call Used when a function call does not pass a mandatory keyword-only argument.

no-value-for-parameter (E1120)
    No value for argument %s in %s call Used when a function call passes too few arguments.

not-an-iterable (E1133)
    Non-iterable value %s is used in an iterating context Used when a non-iterable value is used in place where iterable is expected

not-a-mapping (E1134)
    Non-mapping value %s is used in a mapping context Used when a non-mapping value is used in place where mapping is expected

invalid-sequence-index (E1126)
    Sequence index is not an int, slice, or instance with __index__ Used when a sequence type is indexed with an invalid type. Valid types are ints, slices, and objects with an __index__ method.

invalid-slice-index (E1127)
    Slice index is not an int, None, or instance with __index__ Used when a slice index is not an integer, None, or an object with an __index__ method.

too-many-function-args (E1121)
    Too many positional arguments for %s call Used when a function call passes too many positional arguments.

unexpected-keyword-arg (E1123)
    Unexpected keyword argument %r in %s call Used when a function call passes a keyword argument that doesn't correspond to one of the function's parameter names.

dict-iter-missing-items (E1141)
    Unpacking a dictionary in iteration without calling .items() Emitted when trying to iterate through a dict without calling .items()

unsupported-membership-test (E1135)
    Value '%s' doesn't support membership test Emitted when an instance in membership test expression doesn't implement membership protocol (__contains__/__iter__/__getitem__).

unsubscriptable-object (E1136)
    Value '%s' is unsubscriptable Emitted when a subscripted value doesn't support subscription (i.e. doesn't define __getitem__ method or __class_getitem__ for a class).

keyword-arg-before-vararg (W1113)
    Keyword argument before variable positional arguments list in the definition of %s function When defining a keyword argument before variable positional arguments, one can end up in having multiple values passed for the aforementioned parameter in case the method is called with keyword arguments.

non-str-assignment-to-dunder-name (W1115)
    Non-string value assigned to __name__ Emitted when a non-string value is assigned to __name__

arguments-out-of-order (W1114)
    Positional arguments appear to be out of order Emitted when the caller's argument names fully match the parameter names in the function signature but do not have the same order.

isinstance-second-argument-not-valid-type (W1116)
    Second argument of isinstance is not a type Emitted when the second argument of an isinstance call is not a type.

c-extension-no-member (I1101)
    %s %r has no %r member%s, but source is unavailable. Consider adding this module to extension-pkg-allow-list if you want to perform analysis based on run-time introspection of living objects. Used when a variable is accessed for non-existent member of C extension. Due to unavailability of source static analysis is impossible, but it may be performed by introspecting living objects in run-time.

  Unsupported Version checker

Verbatim name of the checker is unsupported_version.

  Unsupported Version checker Messages

using-f-string-in-unsupported-version (W1601)
    F-strings are not supported by all versions included in the py-version setting Used when the py-version set by the user is lower than 3.6 and pylint encounters a f-string.

using-final-decorator-in-unsupported-version (W1602)
    typing.final is not supported by all versions included in the py-version setting Used when the py-version set by the user is lower than 3.8 and pylint encounters a typing.final decorator.

  Variables checker

Verbatim name of the checker is variables.

  Variables checker Options

init-import
    Tells whether we should check for unused import in __init__ files.

dummy-variables-rgx
    A regular expression matching the name of dummy variables (i.e. expected to not be used).

    Default: _+$|(_[a-zA-Z0-9_]*[a-zA-Z0-9]+?$)|dummy|^ignored_|^unused_

additional-builtins
    List of additional names supposed to be defined in builtins. Remember that you should avoid defining new builtins when possible.

callbacks
    List of strings which can identify a callback function by name. A callback name must start or end with one of those strings.

    Default: cb_,_cb

redefining-builtins-modules
    List of qualified module names which can have objects that can redefine builtins.

    Default: six.moves,past.builtins,future.builtins,builtins,io

ignored-argument-names
    Argument names that match this expression will be ignored. Default to name with leading underscore.

    Default: _.*|^ignored_|^unused_

allow-global-unused-variables
    Tells whether unused global variables should be treated as a violation.

    Default: yes

allowed-redefined-builtins
    List of names allowed to shadow builtins

  Variables checker Messages

unpacking-non-sequence (E0633)
    Attempting to unpack a non-sequence%s Used when something which is not a sequence is used in an unpack assignment

invalid-all-format (E0605)
    Invalid format for __all__, must be tuple or list Used when __all__ has an invalid format.

invalid-all-object (E0604)
    Invalid object %r in __all__, must contain only strings Used when an invalid (non-string) object occurs in __all__.

no-name-in-module (E0611)
    No name %r in module %r Used when a name cannot be found in a module.

undefined-variable (E0602)
    Undefined variable %r Used when an undefined variable is accessed.

undefined-all-variable (E0603)
    Undefined variable name %r in __all__ Used when an undefined variable name is referenced in __all__.

used-before-assignment (E0601)
    Using variable %r before assignment Used when a local variable is accessed before its assignment.

cell-var-from-loop (W0640)
    Cell variable %s defined in loop A variable used in a closure is defined in a loop. This will result in all closures using the same value for the closed-over variable.

global-variable-undefined (W0601)
    Global variable %r undefined at the module level Used when a variable is defined through the "global" statement but the variable is not defined in the module scope.

self-cls-assignment (W0642)
    Invalid assignment to %s in method Invalid assignment to self or cls in instance or class method respectively.

unbalanced-tuple-unpacking (W0632)
    Possible unbalanced tuple unpacking with sequence%s: left side has %d label(s), right side has %d value(s) Used when there is an unbalanced tuple unpacking in assignment

possibly-unused-variable (W0641)
    Possibly unused variable %r Used when a variable is defined but might not be used. The possibility comes from the fact that locals() might be used, which could consume or not the said variable

redefined-builtin (W0622)
    Redefining built-in %r Used when a variable or function override a built-in.

redefined-outer-name (W0621)
    Redefining name %r from outer scope (line %s) Used when a variable's name hides a name defined in the outer scope.

unused-import (W0611)
    Unused %s Used when an imported module or variable is not used.

unused-argument (W0613)
    Unused argument %r Used when a function or method argument is not used.

unused-wildcard-import (W0614)
    Unused import(s) %s from wildcard import of %s Used when an imported module or variable is not used from a 'from X import *' style import.

unused-variable (W0612)
    Unused variable %r Used when a variable is defined but not used.

global-variable-not-assigned (W0602)
    Using global for %r but no assignment is done Used when a variable is defined through the "global" statement but no assignment to this variable is done.

undefined-loop-variable (W0631)
    Using possibly undefined loop variable %r Used when a loop variable (i.e. defined by a for loop or a list comprehension or a generator expression) is used outside the loop.

global-statement (W0603)
    Using the global statement Used when you use the "global" statement to update a global variable. Pylint just try to discourage this usage. That doesn't mean you cannot use it !

global-at-module-level (W0604)
    Using the global statement at the module level Used when you use the "global" statement at the module level since it has no effect

  Pylint and C extensions

If you are getting the dreaded no-member error, there is a possibility that either pylint found a bug in your code or that it actually tries to lint a C extension module.

Linting C extension modules is not supported out of the box, especially since pylint has no way to get an AST object out of the extension module.

But pylint actually has a mechanism which you might use in case you want to analyze C extensions. pylint has a flag, called extension-pkg-allow-list (formerly extension-pkg-whitelist), through which you can tell it to import that module and to build an AST from that imported module:

$ pylint --extension-pkg-allow-list=your_c_extension

Be aware though that using this flag means that extensions are loaded into the active Python interpreter and may run arbitrary code, which you may not want. This is the reason why we disable by default loading C extensions. In case you do not want the hassle of passing C extensions module with this flag all the time, you can enable unsafe-load-any-extension in your configuration file, which will build AST objects from all the C extensions that pylint encounters:

$ pylint --unsafe-load-any-extension=y

Alternatively, since pylint emits a separate error for attributes that cannot be found in C extensions, c-extension-no-member, you can disable this error for your project.

DEVELOPMENT

  Contributing

  Bug reports, feedback

You think you have found a bug in Pylint? Well, this may be the case since Pylint is under heavy development!

Please take the time to check if it is already in the issue tracker at https://github.com/PyCQA/pylint

If you cannot find it in the tracker, create a new issue there or discuss your problem on the code-quality@python.org mailing list or using the discord server https://discord.gg/Egy6P8AMB5.

The code-quality mailing list is also a nice place to provide feedback about Pylint, since it is shared with other tools that aim at improving the quality of python code.

Note that if you don't find something you have expected in Pylint's issue tracker, it may be because it is an issue with one of its dependencies, namely astroid:

•   https://github.com/PyCQA/astroid

  Discord server

https://discord.gg/Egy6P8AMB5

  Mailing lists

You can subscribe to this mailing list at https://mail.python.org/mailman/listinfo/code-quality

Archives are available at https://mail.python.org/pipermail/code-quality/

Archives before April 2013 are available at https://lists.logilab.org/pipermail/python-projects/

  Repository

Pylint is developed using the git distributed version control system.

You can clone Pylint and its dependencies from

git clone https://github.com/PyCQA/pylint
git clone https://github.com/PyCQA/astroid

Got a change for Pylint? Below are a few steps you should take to make sure your patch gets accepted. We recommend using Python 3.8 or higher for development of Pylint as it gives you access to the latest ast parser.

•   Test your code

    For more information on how to use our test suite and write new tests see testing.

•   pylint uses black and isort among other Python autoformatters. We have a pre-commit hook which should take care of the autoformatting for you. To enable it, do the following:

•   install pre-commit using pip install pre-commit

•   then run pre-commit install in the pylint root directory to enable the git hooks.

•   Add a short entry to the ChangeLog describing the change, except for internal implementation only changes. Not usually required, but for changes other than small bugs we also add a couple of sentences in the release document for that release, (What's New section). For the release document we usually write some more details, and it is also a good place to offer examples on how the new change is supposed to work.

•   Add a short entry in doc/whatsnew/VERSION.rst.

•   Add yourself to the CONTRIBUTORS file, flag yourself appropriately (if in doubt, you're a contributor).

•   Write a comprehensive commit message

•   Relate your change to an issue in the tracker if such an issue exists (see Closing issues via commit messages of the GitHub documentation for more information on this)

•   Document your change, if it is a non-trivial one.

•   Send a pull request from GitHub (see About pull requests for more insight about this topic)

  Tips for Getting Started with Pylint Development

•   Read the technical-reference. It gives a short walk through of the pylint codebase and will help you identify where you will need to make changes for what you are trying to implement.

•   astroid.extract_node() is your friend. Most checkers are AST based, so you will likely need to interact with astroid. A short example of how to use astroid.extract_node() is given here.

•   When fixing a bug for a specific check, search the code for the warning message to find where the warning is raised, and therefore where the logic for that code exists.

•   When adding a new checker class you can use the get_unused_message_id_category.py script in ./scripts to get a message id that is not used by any of the other checkers.

  Building the documentation

We use tox for building the documentation:

$ tox -e docs

  Testing

  Test your code!

Pylint is very well tested and has a high code coverage. New contributions are not accepted unless they include tests. Pylint uses two types of tests: unittests and functional tests.

•   The unittests can be found in the /pylint/test directory and they can be used for testing almost anything Pylint related.

•   The functional tests can be found in the /pylint/test/functional directory. They are mainly used to test whether Pylint emits the correct messages.

    Before writing a new test it is often a good idea to ensure that your change isn't breaking a current test. You can run our tests using the tox package, as in:

    python -m tox
    python -m tox -epy36 # for Python 3.6 suite only
    python -m tox -epylint # for running Pylint over Pylint's codebase
    python -m tox -eformatting # for running formatting checks over Pylint's codebase

    It's usually a good idea to run tox with --recreate. This flag tells tox to redownload all dependencies before running the tests. This can be important when a new version of astroid or any of the other dependencies has been published:

    python -m tox --recreate # The entire tox environment will be recreated
    python -m tox --recreate -e py310 # The python 3.10 tox environment will be recreated

    To run only a specific test suite, use a pattern for the test filename (without the .py extension), as in:

    python -m tox -e py310 -- -k test_functional
    python -m tox -e py310 -- -k  \*func\*
    python -m tox --recreate -e py310 -- -k test_functional # With recreation of the environment

    Since we use pytest to run the tests, you can also use it on its own. We do recommend using the tox command though:

    pytest pylint -k test_functional

  Writing functional tests

These are residing under /pylint/test/functional and they are formed of multiple components. First, each Python file is considered to be a test case and it should be accompanied by a .txt file, having the same name, with the messages that are supposed to be emitted by the given test file.

In the Python file, each line for which Pylint is supposed to emit a message has to be annotated with a comment in the form # [message_symbol], as in:

a, b, c = 1 # [unbalanced-tuple-unpacking]

If multiple messages are expected on the same line, then this syntax can be used:

a, b, c = 1.test # [unbalanced-tuple-unpacking, no-member]

You can also use # +n: [ with n an integer if the above syntax would make the line too long or other reasons:

# +1: [empty-comment]
#

If you need special control over Pylint's configuration, you can also create a .rc file, which can have sections of Pylint's configuration. The .rc file can also contain a section [testoptions] to pass options for the functional test runner. The following options are currently supported: "min_pyver": Minimal python version required to run the test "max_pyver": Python version from which the test won't be run. If the last supported version is 3.9 this setting should be set to 3.10. "min_pyver_end_position": Minimal python version required to check the end_line and end_column attributes of the message "requires": Packages required to be installed locally to run the test "except_implementations": List of python implementations on which the test should not run "exclude_platforms": List of operating systems on which the test should not run

During development, it's sometimes helpful to run all functional tests in your current environment in order to have faster feedback. Run from Pylint root directory with:

python tests/test_functional.py

You can use all the options you would use for pytest, for example -k "test_functional[len_checks]". Furthermore, if required the .txt file with expected messages can be regenerated based on the the current output by appending --update-functional-output to the command line:

python tests/test_functional.py --update-functional-output -k "test_functional[len_checks]"

  Writing unittest tests

Most other tests reside in the '/pylint/test' directory. These unittests can be used to test almost all functionality within Pylint. A good step before writing any new unittests is to look at some tests that test a similar funcitionality. This can often help write new tests.

If your new test requires any additional files you can put those in the /pylint/test/regrtest_data directory. This is the directory we use to store any data needed for the unittests.

  Writing functional tests for configurations

To test the different ways to configure Pylint there is also a small functional test framework for configuration files. These tests can be found in the '/pylint/test/config' directory.

To create a new test create a new file with an unused name in the directory of that type of configuration file. Subsequently add a filename.result.json file with 'filename' being the same name as your configuration file. This file should record what the configuration should be compared to the standard configuration.

For example, if the configuration should add a warning to the list of disabled messages and you changed the configuration for job to 10 instead of the default 1 the .json file should include:

"functional_append": {
    "disable": [["a-message-to-be-added"],]
}
"jobs": 10,

Similarly if a message should be removed you can add the following to the .json file:

"functional_remove": {
    "disable": [["a-message-to-be-removed"],]
}

If a configuration is incorrect and should lead to a crash or warning being emitted you can specify this by adding a .out file. This file should have the following name name_of_configuration_testfile.error_code.out. So, if your test is called bad_configuration.toml and should exit with exit code 2 the .out file should be named bad_configuration.2.out. The content of the .out file should have a similar pattern as a normal Pylint output. Note that the module name should be {abspath} and the file name {relpath}.

  Primer tests

Pylint also uses what we refer to as primer tests. These are tests that are run automatically in our Continuous Integration and check whether any changes in Pylint lead to crashes or fatal errors on the stdlib and a selection of external repositories.

To run the primer tests you can add either --primer-stdlib or --primer-external to the pytest command. If you want to only run the primer you can add either of their marks, for example:

pytest -m primer_stdlib --primer-stdlib

The external primer has been split up in two marks to speed up our Continuous Integration. You can run either of the two batches or run them both:

pytest -m primer_external_batch_one --primer-external # Runs batch one
pytest -m primer_external_batch_two --primer-external # Runs batch two
pytest -m "primer_external_batch_one or primer_external_batch_two" --primer-external # Runs both batches

The list of repositories is created on the basis of three criteria: 1) projects need to use a diverse range of language features, 2) projects need to be well maintained and 3) projects should not have a codebase that is too repetitive. This guarantees a good balance between speed of our CI and finding potential bugs.

You can find the latest list of repositories and any relevant code for these tests in the tests/primer directory.

ADDITIONAL COMMANDS

Pylint ships with some additional tools that can be executed from the command line once Pylint itself is installed.

  Pyreverse

pyreverse analyzes your source code and generates package and class diagrams. It supports output to .dot/.gv, .vcg and .puml/.plantuml (PlantUML) file formats. If Graphviz (or the dot command) is installed, all output formats supported by Graphviz can be used as well. In this case, pyreverse first generates a temporary .gv file, which is then fed to Graphviz to generate the final image.

  Running Pyreverse

To run pyreverse, use:

pyreverse [options] <packages>

<packages> can also be a single Python module. To see a full list of the available options, run:

pyreverse -h

  Example Output

Example diagrams generated with the .puml output format are shown below.

  Class Diagram
[image: Class diagram generated by pyreverse] [image]

  Package Diagram
[image: Package diagram generated by pyreverse] [image]

  Creating Class Diagrams for Specific Classes

In many cases creating a single diagram depicting all classes in the project yields a rather unwieldy, giant diagram. While limiting the input path to a single package or module can already help greatly to narrow down the scope, the -c option provides another way to create a class diagram focusing on a single class and its collaborators. For example, running:

pyreverse -ASmy -c pylint.checkers.classes.ClassChecker pylint

will generate the full class and package diagrams for pylint, but will additionally generate a file pylint.checkers.classes.ClassChecker.dot: [image: Package diagram generated by pyreverse] [image]

  Symilar

The console script symilar finds copy pasted blocks in a set of files. It provides a command line interface to the Similar class, which includes the logic for Pylint's duplicate-code message. It can be invoked with:

symilar [-d|--duplicates min_duplicated_lines] [-i|--ignore-comments] [--ignore-docstrings] [--ignore-imports] [--ignore-signatures] file1...

All files that shall be checked have to be passed in explicitly, e.g.:

symilar foo.py, bar.py, subpackage/spam.py, subpackage/eggs.py

symilar produces output like the following:

17 similar lines in 2 files
==tests/data/clientmodule_test.py:3
==tests/data/suppliermodule_test.py:12
  class Ancestor:
      """ Ancestor method """
      __implements__ = (Interface,)
      cls_member = DoNothing()
      def __init__(self, value):
          local_variable = 0
          self.attr = 'this method shouldn\'t have a docstring'
          self.__value = value
      def get_value(self):
          """ nice docstring ;-) """
          return self.__value
      def set_value(self, value):
          self.__value = value
          return 'this method shouldn\'t have a docstring'
TOTAL lines=58 duplicates=17 percent=29.31

FREQUENTLY ASKED QUESTIONS

  1. About Pylint

  1.1 What is Pylint?

Pylint is a static code checker, meaning it can analyse your code without actually running it. Pylint checks for errors, tries to enforce a coding standard, and tries to enforce a coding style.

  2. Installation

  2.1 How do I install Pylint?

Everything should be explained on installation.

  2.2 What kind of versioning system does Pylint use?

Pylint uses git. To get the latest version of Pylint from the repository, simply invoke

git clone https://github.com/PyCQA/pylint

  2.3 What are Pylint's dependencies?

Pylint depends on astroid and a couple of other packages. See the following section for details on what versions of Python are supported.

  2.4 What versions of Python is Pylint supporting?

The supported running environment since Pylint 2.12.1 is Python 3.6.2+.

  3. Running Pylint

  3.1 Can I give pylint a file as an argument instead of a module?

Pylint expects the name of a package or module as its argument. As a convenience, you can give it a file name if it's possible to guess a module name from the file's path using the python path. Some examples :

"pylint mymodule.py" should always work since the current working directory is automatically added on top of the python path

"pylint directory/mymodule.py" will work if "directory" is a python package (i.e. has an __init__.py file), an implicit namespace package or if "directory" is in the python path.

"pylint /whatever/directory/mymodule.py" will work if either:

•   "/whatever/directory" is in the python path

•   your cwd is "/whatever/directory"

•

directory is a python package and /whatever is in the python
    path

•   "directory" is an implicit namespace package and is in the python path.

•

directory is a python package and your cwd is /whatever and so
    on...

  3.2 Where is the persistent data stored to compare between successive runs?

Analysis data are stored as a pickle file in a directory which is localized using the following rules:

•   value of the PYLINTHOME environment variable if set

•   "pylint" subdirectory of the user's XDG_CACHE_HOME if the environment variable is set, otherwise

•   Linux: "~/.cache/pylint"

•   Mac OS X: "~/Library/Caches/pylint"

•   Windows: "C:Users<username>AppDataLocalpylint"

•   ".pylint.d" directory in the current directory

  3.3 How do I find the option name (for pylintrc) corresponding to a specific command line option?

You can generate a sample pylintrc file with --generate-rcfile Every option present on the command line before this will be included in the rc file

For example:

pylint --disable=bare-except,invalid-name --class-rgx='[A-Z][a-z]+' --generate-rcfile

  3.4 I'd rather not run Pylint from the command line. Can I integrate it with my editor?

Much probably. Read ide-integration

  4. Message Control

  4.1 How to disable a particular message?

For a single line : Add #pylint: disable=some-message,another-one at the end of the desired line of code. Since Pylint 2.10 you can also use #pylint: disable-next=... on the line just above the problem. ... in the following example is a short hand for the list of messages you want to disable.

For larger disable : You can add #pylint: disable=... at the block level to disable for the block. It's possible to enable for the reminder of the block with #pylint: enable=... A block is either a scope (say a function, a module), or a multiline statement (try, finally, if statements, for loops). It's currently impossible to disable inside an else block

Read message-control for details and examples.

  4.2 Is there a way to disable a message for a particular module only?

Yes, you can disable or enable (globally disabled) messages at the module level by adding the corresponding option in a comment at the top of the file:

# pylint: disable=wildcard-import, method-hidden
# pylint: enable=too-many-lines

  4.3 How can I tell Pylint to never check a given module?

Add #pylint: skip-file at the beginning of the module.

In order to ease finding which modules are ignored an Information-level message file-ignored is emitted.

  4.4 Do I have to remember all these numbers?

No, you can use symbolic names for messages:

# pylint: disable=fixme, line-too-long

  4.5 I have a callback function where I have no control over received arguments. How do I avoid getting unused argument warnings?

Prefix (ui) the callback's name by cb_, as in cb_onclick(...). By doing so arguments usage won't be checked. Another solution is to use one of the names defined in the "dummy-variables" configuration variable for unused argument ("_" and "dummy" by default).

  4.6 What is the format of the configuration file?

Pylint uses ConfigParser from the standard library to parse the configuration file. It means that if you need to disable a lot of messages, you can use tricks like:

# disable wildcard-import, method-hidden and too-many-lines because I do
# not want it
disable= wildcard-import,
 method-hidden,
 too-many-lines

  4.7 Why are there a bunch of messages disabled by default?

pylint does have some messages disabled by default, either because they are prone to false positives or that they are opinionated enough for not being included as default messages.

You can see the plugin you need to explicitly load in the technical reference

  4.8 I am using another popular linter alongside pylint. Which messages should I disable to avoid duplicates?

pycodestyle: unneeded-not, line-too-long, unnecessary-semicolon, trailing-whitespace, missing-final-newline, bad-indentation, multiple-statements, bare-except

pyflakes: undefined-variable, unused-import, unused-variable

mccabe: too-many-branches

pydocstyle: missing-module-docstring, missing-class-docstring, missing-function-docstring

pep8-naming: invalid-name, bad-classmethod-argument, bad-mcs-classmethod-argument, no-self-argument

isort: wrong-import-order

flake8-import-order: wrong-import-order

  5. Classes and Inheritance

  5.1 When is Pylint considering a class as an abstract class?

A class is considered as an abstract class if at least one of its methods is doing nothing but raising NotImplementedError.

  5.2 How do I avoid access to undefined member messages in my mixin classes?

To do so you have to set the ignore-mixin-members option to "yes" (this is the default value) and name your mixin class with a name which ends with "Mixin" or "mixin" (default) or change the default value by changing the mixin-class-rgx option.

  6. Troubleshooting

  6.1 Pylint gave my code a negative rating out of ten. That can't be right!

Even though the final rating Pylint renders is nominally out of ten, there's no lower bound on it. By default, the formula to calculate score is

10.0 - ((float(5 * error + warning + refactor + convention) / statement) * 10)

However, this option can be changed in the Pylint rc file. If having negative values really bugs you, you can set the formula to be the maximum of 0 and the above expression.

  6.2 I think I found a bug in Pylint. What should I do?

Read Bug reports, feedback

  6.3 I have a question about Pylint that isn't answered here.

Read Mailing lists

SOME PROJECTS USING PYLINT

The following projects are known to use Pylint to help develop better Python code:

•   edX (https://github.com/edx)

•   qutebrowser (https://github.com/The-Compiler/qutebrowser)

•   Odoo (https://github.com/OCA)

•   Landscape.io (https://github.com/landscapeio/)

•   Codacy (https://github.com/Codacy/)

•   SaltStack (https://github.com/saltstack)

•   CodeFactor (https://github.com/codefactor-io)

•   many more...

SUPPORT
[image: Tidelift] [image]

Professional support for pylint is available as part of the Tidelift Subscription. Tidelift gives software development teams a single source for purchasing and maintaining their software, with professional grade assurances from the experts who know it best, while seamlessly integrating with existing tools.

WHAT'S NEW IN PYLINT

High level descriptions of the most important changes between major Pylint versions.

  What's New in Pylint 2.13

Release
    2.13

Date
    TBA

  Summary -- Release highlights

  New checkers

  Removed checkers

  Extensions

  Other Changes

•   Require Python 3.6.2 to run pylint.

    Closes #5065

  What's New in Pylint 2.12

Release
    2.12

Date
    2021-11-24

  Summary -- Release highlights

In 2.12, we introduced a new option py-version that permits to analyse code for a python version that may differ from your current python interpreter. This does not affect all checkers but permits, for example, to check for python 3.5 code smells (using f-string's) while using pylint with python 3.6. The minimum version to run pylint is now 3.6.2, while the last working version for python 3.6.0 and 3.6.1 was pylint 2.9.3.

On top of fixing a lot of false positives and bugs, we also added new default checks, like use-implicit-booleaness-not-comparison, overridden-final-method, and useless-with-lock. There's also better check for TOML configurations.

Lastly, in addition to the information we already had about start line and start column, we introduced new information about the end line and end column of messages. This will permit to have more precise visual clue in IDE like in pylint for vs-code. The default will stay the same to not break compatibility but it can be retrieved by adding end_line and end_column to the --msg-template option. For better result stick to python 3.8+.

The checker for Yoda conditions is now an extension, you might want to enable it if you were relying on this check. There's also a new extension checker, consider-using-any-or-all that detects for loops that could be replaced by any or all, entirely contributed by @areveny, welcome to the team !

  New checkers

•   Added missing-any-param-doc triggered when a function has neither parameter nor parameter type documentation. Undocumented parameters are now being properly identified. A warning might start to appear unexpectedly if missing-param-doc and missing-type-doc were disabled, as a new message missing-any-param-doc will be emitted instead.

    Closes #3799

•   Checkers for typing.final

•   Added overridden-final-method: Emitted when a method which is annotated with typing.final is overridden

•   Added subclassed-final-class: Emitted when a class which is annotated with typing.final is subclassed

    Closes #3197

•   Created new UnsupportedVersionChecker checker class that includes checks for features not supported by all versions indicated by a py-version.

•   Added using-f-string-in-unsupported-version checker. Issued when py-version is set to a version that does not support f-strings (< 3.6)

•   Added new checker use-implicit-booleaness-not-comparison: Emitted when collection literal comparison is being used to check for emptiness.

    Closes #4774

•   Added using-final-decorator-in-unsupported-version checker. Issued when py-version is set to a version that does not support typing.final (< 3.8)

•   Added new checker useless-with-lock to find incorrect usage of with statement and threading module locks. Emitted when with threading.Lock(): is used instead of with lock_instance:.

    Closes #5208

•   A new bad-configuration-section checker was added that will emit for misplaced option in pylint's top level namespace for toml configuration. Top-level dictionaries or option defined in the wrong section will still silently not be taken into account, which is tracked in a follow-up issue.

    Follow-up in #5259

•   MessageTest of the unittest testutil now requires the confidence attribute to match the expected value. If none is provided it is set to UNDEFINED.

•   add_message of the unittest testutil now actually handles the col_offset parameter and allows it to be checked against actual output in a test.

  Extensions

•   Added an optional extension consider-using-any-or-all: Emitted when a for loop only produces a boolean and could be replaced by any or all using a generator. Also suggests a suitable any/all statement if it is concise.

    Closes #5008

•   Moved misplaced-comparison-constant to its own extension comparison_placement. This checker was opinionated and now no longer a default. It can be reactived by adding pylint.extensions.comparison_placement to load-plugins in your config.

    Closes #1064

  Other Changes

•   Fix install graphiz message which isn't needed for puml output format.

•   pylint no longer crashes when checking assignment expressions within if-statements

    Closes #5178

•   Added configuration option exclude-too-few-public-methods to allow excluding classes from the min-public-methods checker.

    Closes #3370

•   Fix accept-no-yields-doc and accept-no-return-doc not allowing missing yield or return documentation when a docstring is partially correct

    Closes #5223

•   Fix simplify-boolean-expression when condition can be inferred as False.

    Closes #5200

•   Fix exception when pyreverse parses property function of a class.

•   Improve and flatten unused-wildcard-import message

    Closes #3859

•   In length checker, len-as-condition has been renamed as use-implicit-booleaness-not-len in order to be consistent with use-implicit-booleaness-not-comparison.

•   Fixed protected-access for accessing of attributes and methods of inner classes

    Closes #3066

•   Update literal-comparison` checker to ignore tuple literals

    Closes #3031

•   The functional testutils now accept end_lineno and end_column. Expected output files without these will trigger a DeprecationWarning. Expected output files can be easily updated with the python tests/test_functional.py --update-functional-output command.

•   The functional testutils now correctly check the distinction betweeen HIGH and UNDEFINED confidence. Expected output files without defiend confidence levels will now trigger a DeprecationWarning. Expected output files can be easily updated with the python tests/test_functional.py --update-functional-output command.

•   The functional test runner now supports the option min_pyver_end_position to control on which python versions the end_lineno and end_column attributes should be checked. The default value is 3.8.

•   undefined-variable now correctly flags variables which only receive a type annotations and never get assigned a value

    Closes #5140

•   undefined-variable now correctly considers the line numbering and order of classes used in metaclass declarations

    Closes #4031

•   used-before-assignment now correctly considers references to classes as type annotation or default values in first-level methods

    Closes #3771

•   undefined-variable and unused-variable now correctly trigger for assignment expressions in functions defaults

    Fixes part of #3688

•   self-cls-assignment now also considers tuple assignment

•   undefined-variable now correctly triggers for assignment expressions in if ... else statements This includes a basic form of control flow inference for if ... else statements using constant boolean values

    Closes #3688

•   Fix crash for unused-private-member when checking private members on __class__

    Closes #5261

•   Fix double emitting of not-callable on inferrable properties

    Closes #4426

•   Support configuring mixin class pattern via mixin-class-rgx

•   Normalize the input to the ignore-paths option to allow both Posix and Windows paths

    Closes #5194

•   mising-param-doc now correctly parses asterisks for variable length and keyword parameters

    Closes #3733

•   mising-param-doc now correctly handles Numpy parameter documentation without explicit typing

    Closes #5222

•   The --jobs parameter now falls back to 1 if the host operating system does not have functioning shared semaphore implementation.

    Closes #5216

•   Crashes when a list is encountered in a toml configuration do not happen anymore.

    Closes #4580

•   Fix crash for protected-access on (outer) class traversal

•   Fix useless-super-delegation false positive when default keyword argument is a variable.

•   Make yn validator case insensitive, to allow for True and False in config files.

•   The last version compatible with python '3.6.0' and '3.6.1' is pylint '2.9.3'. We did not realize that when adding incompatible typing at the time, and all versions since are broken for this interpreter. 2.12.0 meta-information will permit to download pylint on those interpreters but the installation will fail and tell you to install '2.9.3' instead. pylint 2.12.1 will require python >= 3.6.2.

    Closes #5171 Follow-up in #5065

•   Added the --enable-all-extensions command line option. It will load all available extensions which can be listed by running --list-extensions

•   It is now recommended to do pylint development on Python 3.8 or higher. This allows using the latest ast parser.

•   All standard jobs in the pylint CI now run on Python 3.8 by default. We still support python 3.6 and 3.7 and run tests for those interpreters.

•   Fix crash on open() calls when the mode argument is not a simple string.

    Partially closes #5321

•   Add ability to add end_line and end_column to the --msg-template option. With the standard TextReporter this will add the line and column number of the end of a node to the output of Pylint. If these numbers are unknown, they are represented by an empty string.

•   Introduced primer tests and a configuration tests framework. The helper classes available in pylint/testutil/ are still unstable and might be modified in the near future.

    Closes #4412 #5287

•   Add endLine and endColumn keys to output of JSONReporter.

    Closes #5380

•   Fix false negative for consider-iterating-dictionary during membership checks encapsulated in iterables or not in checks

    Closes #5323

  What's New in Pylint 2.11

Release
    2.11

Date
    2021-09-16

  Summary -- Release highlights

In 2.11, we added a new default checker to advise using f-string as it's the most efficient way of formatting strings right now. You can use pyupgrade or flynt to migrate your old % and format() automatically.

We added a new extension SetMembershipChecker that will advise the use of set for membership test, as it's more performant than lists or tuples. The CodeStyleChecker also got some love, check it out if you're not already using it.

We fixed some long standing bugs, false positives, or false negatives and we added small quality of life options like min-similarity-lines that disable the duplication check when set to 0.

Under the hood the code for both pylint and astroid is progressively more typed, which could be helpful to you if you're using them as libraries. In order for this new typing to make more sense and stay simple, we deprecated some functions or type that will be removed in the next major version. This is an ongoing effort.

The future possible-forgotten-f-prefix check still had too much false positives, and is delayed again. Check the possible-forgotten-f-prefix issue if you want to provide knowledge or use case :)

  New checkers

•   Added consider-using-f-string: Emitted when .format() or '%' is being used to format a string.

    Closes #3592

  Removed checkers

•   The python3 porting mode checker and it's py3k option were removed. You can still find it in older pylint versions.

  Extensions

•   Added new extension SetMembershipChecker with use-set-for-membership check: Emitted when using an in-place defined list or tuple to do a membership test. sets are better optimized for that.

    Closes #4776

•   CodeStyleChecker

•   Added consider-using-assignment-expr: Emitted when an assignment is directly followed by an if statement and both can be combined by using an assignment expression :=. Requires Python 3.8

    Closes #4862

  Other Changes

•   Added py-version config key (if [MASTER] section). Used for version dependant checks. Will default to whatever Python version pylint is executed with.

•   The invalid-name message is now more detailed when using multiple naming style regexes.

•   Fix false positive for consider-using-with if a context manager is assigned to a variable in different paths of control flow (e. g. if-else clause).

    Closes #4751

•   Fix false positive for function-redefined for simple type annotations

    Closes #4936

•   Fix false positive for protected-access if a protected member is used in type hints of function definitions

•   Fix false positive dict-iter-missing-items for dictionaries only using tuples as keys

    Closes #3282

•   The unspecified-encoding checker now also checks calls to pathlib.Path().read_text() and pathlib.Path().write_text()

    Closes #4945

•   Fix false positive superfluous-parens for tuples created with inner tuples

    Closes #4907

•   Fix false positive unused-private-member for accessing attributes in a class using cls

    Closes #4849

•   Extended consider-using-in check to work for attribute access.

•   Setting min-similarity-lines to 0 now makes the similarty checker stop checking for duplicate code

    Closes #4901

•   Fix a bug where pylint complained if the cache's parent directory does not exist

    Closes #4900

•   The global-variable-not-assigned checker now catches global variables that are never reassigned in a local scope and catches (reassigned) functions

    Closes #1375 Closes #330

•   The consider-iterating-dictionary checker now also considers membership checks

    Closes #4069

  What's New in Pylint 2.10

Release
    2.10

Date
    2021-08-20

  Summary -- Release highlights

In 2.10, we added several new default check, like unspecified-encoding, forgotten-debug-statement or use-dict-literal. There's also a few opinionated optional one. You can now forbid while loop or profess your exclusive love of ternary expressions publicly. We promise you hours of arguing fun with your whole team if you add those to your configuration.

We've also fixed some long standing bugs, false positives, or missing options like ignore-signature that will now work on inner function's signatures.

A new option to disable the next line, disable-next, has been added. It's also possible to export colored diagrams, and plantuml diagram using pyreverse. PYLINT_HOME is now XDG_CACHE_HOME if not set.

The performance of the similarity checker has been improved, as well as several small performance fixes.

We're going to continue working on improving performance during 2.11. We're also going to finalize a new possible-forgotten-f-prefix check that had too much false positives at release time. Check the possible-forgotten-f-prefix issue if you want to provide knowledge or use case :)

  New checkers

•   Added unspecified-encoding: Emitted when open() is called without specifying an encoding

    Closes #3826

•   Added use-list-literal: Emitted when list() is called with no arguments instead of using []

    Closes #4365

•   Added use-dict-literal: Emitted when dict() is called with no arguments instead of using {}

    Closes #4365

•   Added forgotten-debug-statement: Emitted when breakpoint, pdb.set_trace or sys.breakpointhook calls are found

    Closes #3692

•   Added use-sequence-for-iteration: Emitted when iterating over an in-place defined set.

•   Added format-string-without-interpolation checker: Emitted when formatting is applied to a string without any variables to be replaced

    Closes #4042

•   Added redundant-u-string-prefix checker: Emitted when the u prefix is added to a string

    Closes #4102

  Extensions

•   CodeStyleChecker

•   Limit consider-using-tuple to be emitted only for in-place defined lists.

•   Emit consider-using-tuple even if list contains a starred expression.

•   Added optional extension consider-ternary-expression: Emitted whenever a variable is assigned in both branches of an if/else block.

    Closes # 4366

•   Added optional extension while-used: Emitted whenever a while loop is used.

    Closes # 4367

  Other Changes

•   pyreverse now permit to produce colored generated diagram by using the colorized option.

•   Pyreverse - add output in PlantUML format

•   consider-using-with is no longer triggered if a context manager is returned from a function.

•   pylint does not crash with a traceback anymore when a file is problematic. It creates a template text file for opening an issue on the bug tracker instead. The linting can go on for other non problematic files instead of being impossible.

•   Pyreverse - Show class has-a relationships inferred from type-hints

•   Performance of the Similarity checker has been improved.

•   Added time.clock to deprecated functions/methods for python 3.3

•   Added ignored-parents option to the design checker to ignore specific classes from the too-many-ancestors check (R0901).

•   Don't emit no-member error if guarded behind if statement.

    Ref #1162 Closes #1990 Closes #4168

•   Fix false positives for superfluous-parens with walrus operator, ternary operator and inside list comprehension.

    Closes #2818 Closes #3249 Closes #3608 Closes #4346

•   Refactor of --list-msgs & --list-msgs-enabled: both options now show whether messages are emittable with the current interpreter.

    Closes #4778

•   Fix false negative for used-before-assignment when the variable is assigned in an exception handler, but used outside of the handler.

    Closes #626

•   Added disable-next option: allows using # pylint: disable-next=msgid to disable a message for the following line

    Closes #1682

•   Fixed cell-var-from-loop checker: handle cell variables in comprehensions within functions, and function default argument expressions. Also handle basic variable shadowing.

    Closes #2846 Closes #3107

•   Fixed bug with cell-var-from-loop checker: it no longer has false negatives when both unused-variable and used-before-assignment are disabled.

•   Class methods' signatures are now ignored the same way as functions' with similarities "ignore-signatures" option enabled

    Closes #4653

  What's New in Pylint 2.9

Release
    2.9

Date
    2021-06-29

  Summary -- Release highlights

Pylint is now compatible with python 3.10.

A lot of new checks have been added, some non-opinionated performance warnings like use-maxsplit-arg, some consensual style warnings like unnecessary-dict-index-lookup or new deprecation checks.

We're aiming to reduce pylint noise for first time users and making some new checks optional is a step in that direction. In order to do that we created an optional code style checker that can be loaded using pylint.extensions.code_style with the load-plugins options. More than ever, if as a veteran you want the most checks you can possibly get, you should check the list of pylint extensions..

  New checkers

•   deprecated-decorator: Emitted when deprecated decorator is used.

•   consider-using-dict-items: Emitted when iterating over dictionary keys and then indexing the same dictionary with the key within loop body.

•   use-maxsplit-arg: Emitted either when accessing only the first or last element of str.split().

•   An ignore_signatures option has been added to the similarity checker. It will permits to reduce false positives when multiple functions have the same parameters.

•   unnecessary-dict-index-lookup: Emitted when iterating over dictionary items (key-value pairs) and accessing the value by index lookup.

•   consider-using-from-import: Emitted when a submodule/member of a package is imported and aliased with the same name.

•   New checker unused-private-member: Emitted when a private member (i.e., starts with __) of a class is defined but not used.

•   New checker invalid-class-object: Emitted when a non-class is assigned to a __class__ attribute.

•   invalid-all-format: Emitted when __all__ has an invalid format, i.e. isn't a tuple or list.

•   New checker await-outside-async: Emitted when await is used outside an async function.

•   Add new extension CodeStyleChecker. It includes checkers that can improve code consistency. As such they don't necessarily provide a performance benefit and are often times opinionated.

•   consider-using-tuple: Emitted when an in-place defined list or set can be replaced by a tuple.

•   consider-using-namedtuple-or-dataclass: Emitted when dictionary values can be replaced by namedtuples or dataclass instances.

  Other Changes

•   Fix false-positive consider-using-with (R1732) if a ternary conditional is used together with with

•   Fix false-positive consider-using-with (R1732) if contextlib.ExitStack takes care of calling the __exit__ method

•   Add type annotations to pyreverse dot files

•   Pylint's tags are now the standard form vX.Y.Z and not pylint-X.Y.Z anymore.

•   Fix false-positive too-many-ancestors when inheriting from builtin classes, especially from the collections.abc module

•   The output messages for arguments-differ error message have been customized based on the different error cases.

•   New option --fail-on=<msg ids> to return non-zero exit codes regardless of fail-under value.

•   A new error called arguments-renamed has been created, which identifies any changes at the parameter names of overridden functions. It aims to separate the functionality of arguments-differ.

•   Fix incompatibility with Python 3.6.0 caused by typing.Counter and typing.NoReturn usage

•   Allow comma-separated list in output-format and separate output files for each specified format. Each output file can be defined after a semicolon for example : --output-format=json:myfile.json,colorized

•   The using-constant-test checker now detects constant tests consisting of list literals like [] and [1, 2, 3].

•   ignore-paths configuration directive has been added. Defined regex patterns are matched against file path.

•   Added handling of floating point values when parsing configuration from pyproject.toml

•   Fix false positive useless-type-doc on ignored argument using pylint.extensions.docparams when a function was typed using pep484 but not inside the docstring.

•   Fix missing support for detecting deprecated aliases to existing functions/methods. functions/methods.

•   Added various deprecated functions/methods for python 3.10, 3.7, 3.6 and 3.3

•   No longer emit consider-using-with for ThreadPoolExecutor and ProcessPoolExecutor as they have legitimate use cases without a with block.

•   Fix crash if a callable returning a context manager was assigned to a list or dict item

  What's New in Pylint 2.8

Release
    2.8

Date
    2021-04-24

  Summary -- Release highlights

  Breaking changes

•   The 'doc' extra-require has been removed. __pkginfo__` does not contain the package metadata anymore (except numversion, until 3.0). Meta-information are accessible with

    `python from importlib import metadata metadata.metadata('pylint') ` Prefer that to an import from __pkginfo__.

  New checkers

•   New refactoring message consider-using-with. This message is emitted if resource-allocating functions or methods of the standard library (like open() or threading.Lock.acquire()) that can be used as a context manager are called without a with block.

•   Add deprecated-argument check for deprecated arguments.

•   Add new extension ConfusingConsecutiveElifChecker. This optional checker emits a refactoring message (R5601 confusing-consecutive-elif) if if/elif statements with different indentation levels follow directly one after the other.

•   Add consider-using-min-max-builtin check for if statement which could be replaced by Python builtin min or max.

•   Add new extension TypingChecker. This optional checker can detect the use of deprecated typing aliases and can suggest the use of the alternative union syntax where possible. (For example, 'typing.Dict' can be replaced by 'dict', and 'typing.Unions' by '|', etc.) Make sure to check the config options if you plan on using it!

•   Add deprecated-class check for deprecated classes.

  Other Changes

•   New option --output=<file> to output result to a file rather than printing to stdout.

    Closes #1070

•   Reduce usage of blacklist/whitelist terminology. Notably, extension-pkg-allow-list is an alternative to extension-pkg-whitelist and the message blacklisted-name is now emitted as disallowed-name. The previous names are accepted to maintain backward compatibility.

•   The packaging is now done via setuptools exclusively. doc, tests, man, elisp and Changelog are not packaged anymore - reducing the size of the package by 75%.

•   Updated astroid to 2.5.4

•   COPYING has been renamed to LICENSE for standardization.

  What's New in Pylint 2.7

Release
    2.7

Date
    2021-02-21

  Summary -- Release highlights

•   Python 3.6+ is now required.

•   No more duplicate messages when using multiple jobs.

•   Handling of the new typing provided by mypy 0.8

•   Reduced the number of false positives in general

•   Reduced the occurrence of genuinely large recursion that went above system limit (See #3836, for a fix for pandas)

  New checkers

•   Add nan-comparison check for comparison of NaN values

•   Add support to ignored-argument-names in DocstringParameterChecker and adds useless-param-doc and useless-type-doc messages.

•   Add empty-comment check for empty comments.

•   Add simplifiable-condition check for extraneous constants in conditionals using and/or.

•   Add condition-evals-to-constant check for conditionals using and/or that evaluate to a constant.

•   Add consider-using-generator check for the use of list comprehension inside any or all function.

  Other Changes

•   Fix false positive for builtin-not-iterating when zip or map receives iterable

•   Fix linter multiprocessing pool shutdown which triggered warnings when runned in parallels with other pytest plugins.

•   Enums are now required to be named in UPPER_CASE by invalid-name.

•   Fix bug that lead to duplicate messages when using --jobs 2 or more.

•   Adds option check-protected-access-in-special-methods in the ClassChecker to activate/deactivate protected-access message emission for single underscore prefixed attribute in special methods.

•   inconsistent-return-statements message is now emitted if one of try/except statement is not returning explicitly while the other do.

•   Fix false positive message useless-super-delegation when default keyword argument is a dictionary.

•   Fix vulnerable regular expressions in pyreverse. The ambiguities of vulnerable regular expressions are removed, making the repaired regular expressions safer and faster matching.

•   len-as-conditions is now triggered only for classes that are inheriting directly from list, dict, or set and not implementing the __bool__ function, or from generators like range or list/dict/set comprehension. This should reduce the false positive for other classes, like pandas's DataFrame or numpy's Array.

•   Fixes duplicate code detection for --jobs=2+

•   New option allowed-redefined-builtins defines variable names allowed to shadow builtins.

•   Improved protected access checks to allow access inside class methods

  What's New in Pylint 2.6

Release
    2.6

Date
    2020-08-20

  Summary -- Release highlights

•   bad-continuation and bad-whitespace have been removed. black or another formatter can help you with this better than Pylint

•   Added support for isort 5

  New checkers

•   Add super-with-arguments check for flagging instances of Python 2 style super calls.

•   Add raise-missing-from check for exceptions that should have a cause.

  Other Changes

•   bad-continuation and bad-whitespace have been removed. black or another formatter can help you with this better than Pylint

•   The no-space-check option has been removed, it's no longer possible to consider empty line like a trailing-whitespace by using clever options.

•   mixed-indentation has been removed, it is no longer useful since TabError is included directly in python3

•   Fix superfluous-parens false-positive for the walrus operator

•   Add support for both isort 4 and isort 5. If you have pinned isort 4 in your projet requirements, nothing changes. If you use isort 5, though, note that the known-standard-library option is not interpreted the same in isort 4 and isort 5 (see the migration guide in isort documentation for further details). For compatibility's sake for most pylint users, the known-standard-library option in pylint now maps to extra-standard-library in isort 5. If you really want what known-standard-library now means in isort 5, you must disable the wrong-import-order check in pylint and run isort manually with a proper isort configuration file.

  What's New in Pylint 2.5

Release
    2.5

Date
    2020-04-27

  Summary -- Release highlights

  New checkers

•   A new check isinstance-second-argument-not-valid-type was added. This check is emitted whenever pylint finds a call to the isinstance function with a second argument that is not a type. Such code is likely unintended as it will cause a TypeError to be thrown at runtime error.

•   A new check assert-on-string-literal was added. This check is emitted whenever pylint finds an assert statement with a string literal as its first argument. Such assert statements are probably unintended as they will always pass.

•   A new check f-string-without-interpolation was added. This check is emitted whenever pylint detects the use of an f-string without having any interpolated values in it, which means that the f-string can be a normal string.

•   Multiple checks for invalid return types of protocol functions were added:

•   invalid-bool-returned: __bool__ did not return a bool

•   invalid-index-returned: __index__ did not return an integer

•   invalid-repr-returned): __repr__ did not return a string

•   invalid-str-returned): __str__ did not return a string

•   invalid-bytes-returned): __bytes__ did not return a string

•   invalid-hash-returned): __hash__ did not return an integer

•   invalid-length-hint-returned): __length_hint__ did not return a non-negative integer

•   invalid-format-returned): __format__ did not return a string

•   invalid-getnewargs-returned): __getnewargs__ did not return a tuple

•   invalid-getnewargs-ex-returned): __getnewargs_ex__ did not return a tuple of the form (tuple, dict)

•   A new check inconsistent-quotes was added. This check is emitted when quotes delimiters (" and ') are not used consistently throughout a module. It allows avoiding unnecessary escaping, allowing, for example, "Don't error" in a module in which single-quotes otherwise delimit strings so that the single quote in Don't doesn't need to be escaped.

•   A new check non-str-assignment-to-dunder-name was added to ensure that only strings are assigned to __name__ attributes.

  Other Changes

•   Configuration can be read from a setup.cfg or pyproject.toml file in the current directory. A setup.cfg must prepend pylintrc section names with pylint., for example [pylint.MESSAGES CONTROL]. A pyproject.toml file must prepend section names with tool.pylint., for example [tool.pylint.'MESSAGES CONTROL']. These files can also be passed in on the command line.

•   Add new good-names-rgx and bad-names-rgx to enable permitting or disallowing of names via regular expressions

    To enable better handling of permitted/disallowed names, we added two new config options: good-names-rgxs: a comma- separated list of regexes, that if a name matches will be exempt of naming-checking. bad-names-rgxs: a comma- separated list of regexes, that if a name matches will be always marked as a disallowed name.

•   Mutable collections.* are now flagged as dangerous defaults.

•   Add new --fail-under flag for setting the threshold for the score to fail overall tests. If the score is over the fail-under threshold, pylint will complete SystemExit with value 0 to indicate no errors.

•   Added a new option notes-rgx to make fixme warnings more flexible. Now either notes or notes-rgx option can be used to detect fixme warnings.

•   Non-ASCII characters are now allowed by invalid-name.

•   pylint no longer emits invalid-name for non-constants found at module level.

    Pylint was considering all module level variables as constants, which is not what PEP 8 is actually mandating.

•   A new check non-ascii-name was added to detect identifiers with non-ASCII characters.

•   Overloaded typing functions no longer trigger no-self-use, unused-argument, missing-docstring and similar checks that assumed that overloaded functions are normal functions.

•   python -m pylint can no longer be made to import files from the local directory.

•   A new command --list-extensions was added.

    This command lists all extensions present in pylint.extensions.

•   Various false positives have been fixed which you can read more about in the Changelog files.

•   Multiple types of string formatting are allowed in logging functions.

    The logging-fstring-interpolation message has been brought back to allow multiple types of string formatting to be used. The type of formatting to use is chosen through enabling and disabling messages rather than through the logging-format-style option. The fstr value of the logging-format-style option is not valid.

  What's New in Pylint 2.4

Release
    2.4

Date
    2019-09-24

  Summary -- Release highlights

  New checkers

•   import-outside-toplevel

    This check warns when modules are imported from places other than a module toplevel, e.g. inside a function or a class.

•   Added a new check, consider-using-sys-exit

    This check is emitted when we detect that a quit() or exit() is invoked instead of sys.exit(), which is the preferred way of exiting in program.

    Close #2925

•   Added a new check, arguments-out-of-order

    This check warns if you have arguments with names that match those in a function's signature but you are passing them in to the function in a different order.

    Close #2975

•   Added new checks, no-else-break and no-else-continue

    These checks highlight unnecessary else and elif blocks after break and continue statements.

    Close #2327

•   Added unnecessary-comprehension that detects unnecessary comprehensions.

    This check is emitted when pylint finds list-, set- or dict-comprehensions, that are unnecessary and can be rewritten with the list-, set- or dict-constructors.

    Close #2905

•   Added a new check, invalid-overridden-method

    This check is emitted when we detect that a method is overridden as a property or a property is overridden as a method. This can indicate a bug in the application code that will trigger a runtime error.

    Close #2670

•   Added a new check, redeclared-assigned-name

    This check is emitted when pylint detects that a name was assigned one or multiple times in the same assignment, which indicate a potential bug.

    Close #2898

•   Added a new check, self-assigning-variable

    This check is emitted when we detect that a variable is assigned to itself, which might indicate a potential bug in the code application.

    For example, the following would raise this warning:

    def new_a(attr, attr2):
      a_inst = Aclass()
      a_inst.attr2 = attr2
      # should be: a_inst.attr = attr, but have a typo
      attr = attr
      return a_inst

    Close #2930

•   Added a new check property-with-parameters which detects when a property has more than a single argument.

    Close #3006

•   Added subprocess-run-check to handle subprocess.run without explicitly set check keyword.

    Close #2848

•   We added a new check message dict-iter-missing-items. This is emitted when trying to iterate through a dict in a for loop without calling its .items() method.

    Closes #2761

•   We added a new check message missing-parentheses-for-call-in-test. This is emitted in case a call to a function is made inside a test but it misses parentheses.

•   A new check class-variable-slots-conflict was added.

    This check is emitted when pylint finds a class variable that conflicts with a slot name, which would raise a ValueError at runtime.

    For example, the following would raise an error:

    class A:
        __slots__ = ('first', 'second')
        first = 1

•   A new check preferred-module was added.

    This check is emitted when pylint finds an imported module that has a preferred replacement listed in preferred-modules.

    For example, you can set the preferred modules as xml:defusedxml,json:ujson to make pylint suggest using defusedxml instead of xml and ujson rather than json.

•   A new extension broad_try_clause was added.

    This extension enforces a configurable maximum number of statements inside of a try clause. This facilitates enforcing PEP 8's guidelines about try / except statements and the amount of code in the try clause.

    You can enable this extension using --load-plugins=pylint.extensions.broad_try_clause and you can configure the amount of statements in a try statement using --max-try-statements.

  Other Changes

•   Don't emit protected-access when a single underscore prefixed attribute is used inside a special method

    Close #1802

•   len-as-condition now only fires when a len(x) call is made without an explicit comparison.

    The message and description accompanying this checker has been changed reflect this new behavior, by explicitly asking to either rely on the fact that empty sequence are false or to compare the length with a scalar.

    OK:

    if len(x) == 0:
      pass
    while not len(x) == 0:
      pass
    assert len(x) > 5, message

    KO:

    if not len(x):
      pass
    while len(x) and other_cond:
      pass
    assert len(x), message

•   A file is now read from stdin if the --from-stdin flag is used on the command line. In addition to the --from-stdin flag a (single) file name needs to be specified on the command line, which is needed for the report.

•   The checker for ungrouped imports is now more permissive.

    The import can now be sorted alphabetically by import style. This makes pylint compatible with isort.

    The following imports do not trigger an ungrouped-imports anymore

    import unittest
    import zipfile
    from unittest import TestCase
    from unittest.mock import MagicMock

•   The checker for missing return documentation is now more flexible.

    The following does not trigger a missing-return-doc anymore

    def my_func(self):
        """This is a docstring.
        Returns
        -------
        :obj:`list` of :obj:`str`
            List of strings
        """
        return ["hi", "bye"] #@

•   signature-mutators CLI and config option was added.

    With this option, users can choose to ignore too-many-function-args, unexpected-keyword-arg, and no-value-for-parameter for functions decorated with decorators that change the signature of a decorated function.

    For example a test may want to make use of hypothesis. Adding hypothesis.extra.numpy.arrays to signature_mutators would mean that no-value-for-parameter would not be raised for:

    @given(img=arrays(dtype=np.float32, shape=(3, 3, 3, 3)))
    def test_image(img):
        ...

•   Allow the option of f-strings as a valid logging string formatting method.

    logging-fstring--interpolation has been merged into logging-format-interpolation to allow the logging-format-style option to control which logging string format style is valid. To allow this, a new fstr value is valid for the logging-format-style option.

•   --list-msgs-enabled command was added.

    When enabling/disabling several messages and groups in a config file, it can be unclear which messages are actually enabled and which are disabled. This new command produces the final resolved lists of enabled/disabled messages, sorted by symbol but with the ID provided for use with --help-msg.

  What's New in Pylint 2.3

Release
    2.3

Date
    2019-02-27

  Summary -- Release highlights

•   This release improves the performance of the 2.X series after it was affected by a performance regression a couple of releases ago.

  New checkers

•   We added a new check message wrong-exception-operation. This is emitted when an operation is done against an exception, but the operation is not valid for the exception in question. Usually emitted when having binary operations between exceptions in except handlers.

    Closes #2494

•   We added a new no-else-raise warning similar to no-else-return

    Closes #2558

•   We added a new option check-str-concat-over-line-jumps to check implicit-str-concat-in-sequence over multiple lines.

  Other Changes

Quite a lot of bug fixes and improvements went into this release, here's a handful of them. For the full changes, check the Changelog.

•   We no longer emit *-not-iterating checks for builtins consumed by itertools

•   We fixed some false positives for no-self-argument and unsubscriptable-object when using __class_getitem__ (new in Python 3.7)

•   pylint now supports Ellipsis as a synonym for pass statements.

•   fixme gets triggered only on comments.

•   pylint exempts starred unpacking from *-not-iterating Python 3 checks.

•   compare-to-zero is now less zealous by checking against equality and identity.

    ``yield from`` is exempted from ``-not-iterating`` Python 3 checks.

•   A false positive with not-async-context-manager caused by not understanding contextlib.asynccontextmanager was fixed.

•   We refactored bad-reversed-sequence to account for more objects that can define __reversed__.

•   no-member is now emitted for enums when they lack a member.

•   Plugins can now use the load_configuration() hook. This hook is executed after configuration is loaded to prevent overwriting plugin specific configuration via user-based configuration.

•   There's a new command line option list-groups for listing all the check groups pylint knows about. This is useful to know what groups you can disable or enable individually.

  What's New in Pylint 2.2

Release
    2.2

Date
    2018-11-25

  Summary -- Release highlights

  New checkers

•   String checker now reports format string type mismatches.

•   duplicate-string-formatting-argument was added for detecting duplicate string formatting arguments that should be passed instead as named arguments.

•   logging-format-style is a new option for the logging checker for usage of str.format() style format strings in calls to loggers.

    It accepts two options: --logging-format-style=old for using % style formatting, which is the assumed default, and --logging-format-style=new for using {} style formatting.

•   implicit-str-concat-in-sequence detects string concatenation inside lists, sets & tuples.

    Example of code that would generate such warning:

    woops = ('a', 'b' 'c')

  Other Changes

•   try-except-raise checker now handles multilevel inheritance hirerachy for exceptions correctly.

    Close #2484

•   Ignore import x.y.z as z cases for checker useless-import-alias.

•   unnecessary-pass is now also emitted when a function or class contains only docstring and pass statement, in which case, docstring is enough for empty definition.

•   Fix false positive undefined-variable and used-before-assignment with nonlocal keyword usage.

•   Fix exceptions being raised when one of the params is not a ClassDef for checkers.utils.is_subclass_of().

•   pylint now picks the latest value from the inferred values of the exception that gets raised, when looking for raising-non-exception. This helps when reusing a variable name for multiple types, since pylint was picking just the first inferred value, leading to spurious false positives.

    Close #2431

•   pylint used to emit a not-an-iterable error when looking at coroutines built with asyncio.coroutine. This is no longer the case as we handle coroutines explicitly.

    Close #996

•   pylint used to emit an unused-variable error if unused import was found in the function. Now instead of unused-variable, unused-import is emitted.

    Close #2421

  What's New in Pylint 2.1

Release
    2.1

Date
    2018-08-01

  Summary -- Release highlights

•   This release mostly includes fixes for bugs found after the launch of 2.0.

  New checkers

•   A new check was added, misplaced-format-function.

    This message is emitted when pylint detects that a format function is called on non str object. This can occur due to wrong placement of closing bracket, e.g

    print('value: {}').format(123) # bad
    print('value: {}'.format(123)) # good

  Other Changes

•   try-except-raise check was demoted from an error to a warning, as part of issue #2323.

•   Correctly handle the new name of the Python implementation of the abc module.

    In Python 3.7, the abc module has both a C implementation as well as a Python one, but the Python implementation has a different file name that what pylint was expecting, resulting in some checks getting confused.

•   Modules with __getattr__ are exempted by default from no-member

    There's no easy way to figure out if a module has a particular member when the said module uses __getattr__, which is a new addition to Python 3.7. Instead we assume the safe thing to do, in the same way we do for classes, and skip those modules from checking.

•   invalid name is no longer triggered for function and attribute names longer than 30 characters. The upper limit was removed completely.

•   Fix false-positive undefined-variable for self referential class name in lamdbas

•   no-else-return also specifies the type of the branch that is causing the error.

•   Fixed inconsistent behaviour for bad-continuation on first line of file.

•   Fixed a bug where pylint was not able to disable certain messages on the last line through the global disable option.

•   pylint no longer emits useless-return when it finds a single statement that is the return itself

    We still want to be explicit when a function is supposed to return an optional value; even though pass could still work, it's not explicit enough and the function might look like it's missing an implementation.

•   Fixed a bug where pylint was crashing when being unable to infer the value of an argument to next()

•   pylint no longer emit not-an-iterable when dealing with async iterators.

•   pylint gained the ability to specify a default docstring type for when the check cannot guess the type

    For this we added a --default-docstring-type command line option.

  What's New in Pylint 2.0

Release
    2.0

Date
    2018-07-15

  Summary -- Release highlights

•   Dropped support for Python 2. This release will work only on Python 3.4+.

    If you need to use pylint with Python 2, you can use Pylint 1.9+. We'll continue to do bug releases until 2020, when Python 2 goes officially EOL. pylint will gain the ability to analyze Python 2 files, but some checks might not work as they will assume that their running environment is Python 2.

•   Given the dropping of Python 2, the Python 3 porting mode (enabled via --py3k) can now also run with Python 3.

    The porting mode used to be a no-op on Python 3, but most of the messages can now be emitted when the running interpreter is Python 3. The only messages that won't be emitted are those that rely on a particular syntax specific to Python 2, for instance print as a statement.

  New checkers

•   A new check was added, useless-object-inheritance.

    This refactoring message is emitted when pylint detects that a class inherits from object, which is redundant as in Python 3, every class implicitly inherits from object.

    class A(object):
        pass
    class A:    # better
        pass

•   A new check was added, comparison-with-callable.

    This refactoring message is emitted when pylint detects that a comparison with a callable was made, which might suggest that some parenthesis were omitted, resulting in potential unwanted behaviour.

    def foo():
        return None
    def goo():
        return None
    if foo == 786:  # bad
        pass
    if foo() == 786:    # good
        pass

•   A new check was added, chained-comparison.

    This refactoring message is emitted if a boolean operation can be simplified by chaining some of its operations. check below example:

    if a < b and b < c:
        pass
    if a < b < c:   # better
        pass

•   A new check was added, useless-import-alias.

    This refactoring message is emitted when an import alias does not rename the original package.

    import numpy as numpy # bad
    import numpy as np # good
    from collection import OrderedDict as OrderedDict # bad
    from collection import OrderedDict as ordered_dict # good

•   A new check was added, comparison-with-itself.

    This refactoring message is emitted when a variable is compared against itself.

    if variable == variable:  # bad
        pass

•   A new check was added, consider-using-in.

    This refactoring message is emitted when a variable is compared against multiple values concatenated by ors instead of using the faster, more idiomatic "in" check.

    if variable == 1 or variable == 2 or variable == 3:  # bad
        pass
    if variable in (1, 2, 3):  # good
        pass

•   A new check was added, consider-using-get.

    This refactoring message is emitted when manually checking if a key is in a dictionary and getting its value if it is (and optionally a default if not) instead of the more idiomatic dict.get.

    if 'key' in dictionary:  # bad
        variable = dictionary['key']
    else:
        variable = 'default'
    variable = dictionary.get('key', 'default')  # good

•   A new check was added, consider-using-join.

    This refactoring message is emitted when using a for loop over an iterable to join strings instead of the faster, less memory consuming and more idiomatic str.join(sequence).

    result = ''  # bad
    for number in ['1', '2', '3']:
        result += number
    result = ''.join(['1', '2', '3'])  # good

•   New useless-return message when function or method ends with a "return" or "return None" statement and this is the only return statement in the body.

•   New use-symbolic-message-instead message when a message is activated or deactivated by id instead of symbol. The use of symbol is more explicit and easier to remind.

•   A new check was added, consider-swap-variables.

    This refactoring message is emitted when using a temporary variable in order to swap the values of two variables instead of the shorter, more idiomatic approach with tuple-unpacking.

    Instead of a temporary variable, the one-line syntax with commas should be used.

    See this style guide document or this swap values presentation for details.

    temp = a  # the wrong way
    a = b
    b = temp
    a, b = b, a  # the right way

•   Two new checks, invalid-envvar-value and invalid-envvar-default, were added.

    The former is trigger whenever pylint detects that environment variable manipulation functions uses a different type than strings, while the latter is emitted whenever the said functions are using a default variable of different type than expected.

•   A new check was added, subprocess-popen-preexec-fn,

    This refactoring message is emitted when using the keyword argument preexec_fn when creating subprocess.Popen instances which may be unsafe when used in the presence of threads.

    See subprocess.Popen for full warning details.

•   New try-except-raise message when an except handler block has a bare raise statement as its first operator or the exception type being raised is the same as the one being handled.

•   New possibly-unused-variable check added. This is similar to unused-variable, the only difference is that it is emitted when we detect a locals() call in the scope of the unused variable. The locals() call could potentially use the said variable, by consuming all values that are present up to the point of the call. This new check allows to disable this error when the user intentionally uses locals() to consume everything.

    For instance, the following code will now trigger this new error:

    def func():
        some_value = some_call()
        return locals()

•   New unhashable-dict-key check added to detect dict lookups using unhashable keys such as lists or dicts.

•   New self-cls-assignment warning check added.

    This is warning if the first argument of an instance/ class method gets assigned

    class Foo(object):
        def foo(self, bar):
            self = bar

•   New verbose mode option --verbose to display of extra non-checker-related output. Disabled by default.

•   Two new checks were added for recommending dict and set comprehensions where possible.

    These two checks are going to flag the following examples:

    dict([(k, v) for (k, v) in ...]) # better as {k: v for k, v in ...}
    set([k for k in ...]) # better as {k for k in ...}

  Other Changes

•   A couple of performance improvements brought to astroid should make pylint should be a bit faster as well.

    We added a new flag, max_inferable_values on astroid.MANAGER for limitting the maximum amount of values that astroid can infer when inferring values. This change should improve the performance when dealing with large frameworks such as django. You can also control this behaviour with pylint --limit-inference-results

    We also rewrote how nodes_of_class and get_children methods operate which should result in a performance boost for a couple of checks.

•   Fix a false positive inconsistent-return-statements message when exception is raised inside an else statement.

•   Don't warn for missing-type-doc and/or missing-return-type-doc, if type annotations exist on the function signature for a parameter and/or return type.

•   Fix a false positive inconsistent-return-statements message when if statement is inside try/except.

•   Fix a false positive inconsistent-return-statements message when while loop are used.

•   Fix emission of false positive no-member message for class with "private" attributes whose name is mangled.

•   Fix unused-argument false positives with overshadowed variable in dictionary comprehension.

•   Fixing false positive inconsistent-return-statements when never returning functions are used (i.e such as sys.exit).

•   Fix false positive inconsistent-return-statements message when a function is defined under an if statement.

•   Fix false positive inconsistent-return-statements message by avoiding useless exception inference if the exception is not handled.

•   Fix false positive undefined-variable for lambda argument in class definitions

•   Suppress false-positive not-callable messages from certain staticmethod descriptors

•   Expand ignored-argument-names include starred arguments and keyword arguments

•   singleton-comparison will suggest better boolean conditions for negative conditions.

•   undefined-loop-variable takes in consideration non-empty iterred objects before emitting.

    For instance, if the loop iterable is not empty, this check will no longer be emitted.

•   Enum classes no longer trigger too-few-methods

•   Special methods now count towards too-few-methods, and are considered part of the public API. They are still not counted towards the number of methods for too-many-methods.

•   docparams extension allows abstract methods to document returns documentation even if the default implementation does not return something. They also no longer need to document raising a NotImplementedError.

•   Skip wildcard import check for __init__.py.

•   Don't warn 'useless-super-delegation' if the subclass method has different type annotations.

•   Don't warn that a global variable is unused if it is defined by an import

    def func():
        global sys
        import sys

•   Added basic support for postponed evaluation of function annotations.

    If pylint detects the corresponding from __future__ import annotations import, it will not emit used-before-assignment and undefined-variable in the cases triggered by the annotations.

    More details on the postponed evaluation of annotations can be read in PEP 563.

•   A new command line option was added, --exit-zero, for the use of continuous integration scripts which abort if a command returns a non-zero status code. If the option is specified, and Pylint runs successfully, it will exit with 0 regardless of the number of lint issues detected.

    Configuration errors, parse errors, and calling Pylint with invalid command-line options all still return a non-zero error code, even if --exit-zero is specified.

•   Don't emit unused-import anymore for typing imports used in type comments. For instance, in the following example pylint used to complain that Any and List are not used, while they should be considered used by a type checker.

    from typing import Any, List
    a = 1 # type: List[Any]

•   Fix false positive line-too-long for commented lines at the end of module

•   Fix emitting useless-super-delegation when changing the default value of keyword arguments.

•   Support typing.TYPE_CHECKING for unused-import errors

    When modules are imported under typing.TYPE_CHECKING guard, pylint will no longer emit unused-import.

•   Fix false positive unused-variable in lambda default arguments

•   assignment-from-no-return considers methods as well as functions.

    If you have a method that doesn't return a value, but later on you assign a value to a function call to that method (so basically it will be None), then pylint is going to emit an assignment-from-no-return error.

•   A new flag was added, --ignore-none which controls the no-member behaviour with respect to None values.

    Previously pylint was not emitting no-member if it inferred that the owner of an attribute access is a None value. In some cases, this might actually cause bugs, so if you want to check for None values as well, pass --ignore-none=n to pylint.

•   Fix false-positive bad-continuation for with statements

•   Fix false-positive bad-whitespace message for typing annoatations with ellipses in them

•   Fix false-positive undefined-variable for nested lambdas

  What's New In Pylint 1.9

Release
    1.9

Date
    2018-05-15

  Summary -- Release highlights

•   None so far

  New checkers

•   A new Python 3 checker was added to warn about the removed operator.div function.

•   A new Python 3 checker was added to warn about accessing functions that have been moved from the urllib module in corresponding subpackages, such as urllib.request.

    from urllib import urlencode

    Instead the previous code should use urllib.parse or six.moves to import a module in a Python 2 and 3 compatible fashion:

    from six.moves.urllib.parse import urlencode

    To have this working on Python 3 as well, please use the six library:

    six.reraise(Exception, "value", tb)

•   A new check was added to warn about using unicode raw string literals. This is a syntax error in Python 3:

    a = ur'...'

•   Added a new deprecated-sys-function check, emitted when accessing removed sys members.

•   Added xreadlines-attribute check, emitted when the xreadlines() attribute is accessed on a file object.

•   Added two new Python 3 porting checks, exception-escape and comprehension-escape

    These two are emitted whenever pylint detects that a variable defined in the said blocks is used outside of the given block. On Python 3 these values are deleted.

    try:
      1/0
    except ZeroDivisionError as exc:
       ...
    print(exc) # This will raise a NameError on Python 3
    [i for i in some_iterator if some_condition(i)]
    print(i) # This will raise a NameError on Python 3

  Other Changes

•   defaultdict and subclasses of dict are now handled for dict-iter-* checks. That means that the following code will now emit warnings for when iteritems and friends are accessed:

    some_dict = defaultdict(list)
    ...
    some_dict.iterkeys()

•   Enum classes no longer trigger too-few-methods

•   Special methods now count towards too-few-methods, and are considered part of the public API. They are still not counted towards the number of methods for too-many-methods.

•   docparams allows abstract methods to document returns documentation even if the default implementation does not return something. They also no longer need to document raising a NotImplementedError.

  What's New In Pylint 1.8

Release
    1.8

Date
    2017-12-15

  Summary -- Release highlights

•   None so far

  New checkers

•   A new check was added, shallow-copy-environ.

    This warning message is emitted when shallow copy of os.environ is created. Shallow copy of os.environ doesn't work as people may expect. os.environ is not a dict object but rather a proxy object, so any changes made on copy may have unexpected effects on os.environ

    Instead of copy.copy(os.environ) method os.environ.copy() should be used.

    See https://bugs.python.org/issue15373 for details.

    import copy
    import os
    wrong_env_copy = copy.copy(os.environ)  # will emit pylint warning
    wrong_env_copy['ENV_VAR'] = 'new_value'  # changes os.environ
    assert os.environ['ENV_VAR'] == 'new_value'
    good_env_copy = dict(os.environ)  # the right way
    good_env_copy['ENV_VAR'] = 'different_value'  # doesn't change os.environ
    assert os.environ['ENV_VAR'] == 'new_value'

•   A new check was added, keyword-arg-before-vararg.

    This warning message is emitted when a function is defined with a keyword argument appearing before variable-length positional arguments (*args). This may lead to args list getting modified if keyword argument's value is not provided in the function call assuming it will take default value provided in the definition.

    def foo(a, b=3, *args):
        print(a, b, args)
    # Case1: a=0, b=2, args=(4,5)
    foo(0,2,4,5) # 0 2 (4,5) ==> Observed values are same as expected values
    # Case2: a=0, b=<default_value>, args=(4,5)
    foo(0,4,5) # 0 4 (5,) ==> args list got modified as well as the observed value of b
    # Case3: Syntax Error if tried as follows
    foo(0,b=2,4,5) # syntax error

•   A new check was added, simplify-boolean-expression.

    This message is emitted when consider-using-ternary check would emit not equivalent code, due to truthy element being falsy in boolean context.

    value = condition and False or other_value

    This flawed construct may be simplified to:

    value = other_value

•   A new check was added, bad-thread-instantiation.

    This message is emitted when the threading.Thread class does not receive the target argument, but receives just one argument, which is by default the group parameter.

    In the following example, the instantiation will fail, which is definitely not desired:

    import threading
    threading.Thread(lambda: print(1)) # Oups, this is the group parameter

•   A new Python 3 checker was added to warn about accessing functions that have been removed from the itertools module izip, imap, iflter, izip_longest, and ifilterfalse.

    from itertools import izip
    print(list(izip([1, 2], [3])))

    Instead use six.moves to import a Python 2 and Python 3 compatible function:

    from six.moves import zip
    print(list(zip([1, 2], [3])))

•   A new Python 3 checker was added to warn about accessing deprecated fields from the types module like ListType or IntType

    from types import ListType
    print(isinstance([], ListType))

    Instead use the declarations in the builtin namespace:

    print(isinstance([], list))

•   A new Python 3 checker was added to warn about declaring a next method that would have implemented the Iterator protocol in Python 2 but is now a normal method in Python 3.

    class Foo(object):
        def next(self):
            return 42

    Instead implement a __next__ method and use six.Iterator as a base class or alias next to __next__:

    class Foo(object):
        def __next__(self):
            return 42
        next = __next__

•   Three new Python 3 checkers were added to warn about using dictionary methods in non-iterating contexts.

    For example, the following are returning iterators in Python 3:

    .. code-block:: python
    d = {} d.keys()[0] d.items()[0] d.values() + d.keys()

•   A new Python 3 porting check was added, non-ascii-bytes-literals

    This message is emitted whenever we detect that a bytes string contain non-ASCII characters, which results in a SyntaxError on Python 3.

•   A new warning, raising-format-tuple, will catch situations where the intent was likely raising an exception with a formatted message string, but the actual code did omit the formatting and instead passes template string and value parameters as separate arguments to the exception constructor. So it detects things like

    raise SomeError('message about %s', foo)
    raise SomeError('message about {}', foo)

    which likely were meant instead as

    raise SomeError('message about %s' % foo)
    raise SomeError('message about {}'.format(foo))

    This warning can be ignored on projects which deliberately use lazy formatting of messages in all user-facing exception handlers.

•   Following the recommendations of PEP479 ,a new Python 3.0 checker was added to warn about raising a StopIteration inside a generator. Raising a StopIteration inside a generator may be due a direct call to raise StopIteration:

    def gen_stopiter():
        yield 1
        yield 2
        yield 3
        raise StopIteration

    Instead use a simple return statement

    def gen_stopiter():
        yield 1
        yield 2
        yield 3
        return

    Raising a StopIteration may also be due to the call to next function with a generator as argument:

    def gen_next_raises_stopiter():
        g = gen_ok()
        while True:
            yield next(g)

    In this case, surround the call to next with a try/except block:

    def gen_next_raises_stopiter():
        g = gen_ok()
        while True:
            try:
                yield next(g)
            except StopIteration:
                return

    The check about raising a StopIteration inside a generator is also valid if the exception raised inherit from StopIteration. Close #1385

•   A new Python checker was added to warn about using a + operator inside call of logging methods when one of the operands is a literal string:

    import logging
    var = "123"
    logging.log(logging.INFO, "Var: " + var)

    Instead use formatted string and positional arguments :

    import logging
    var = "123"
    logging.log(logging.INFO, "Var: %s", var)

•   A new Python checker was added to warn about inconsistent-return-statements. A function or a method has inconsistent return statements if it returns both explicit and implicit values :

    def mix_implicit_explicit_returns(arg):
        if arg < 10:
            return True
        elif arg < 20:
            return

    According to PEP8, if any return statement returns an expression, any return statements where no value is returned should explicitly state this as return None, and an explicit return statement should be present at the end of the function (if reachable). Thus, the previous function should be written:

    def mix_implicit_explicit_returns(arg):
        if arg < 10:
            return True
        elif arg < 20:
            return None

    Close #1267

  Other Changes

•   Fixing u'' string in superfluous-parens message.

•   Configuration options of invalid name checker are significantly redesigned. Predefined rules for common naming styles were introduced. For typical setups, user friendly options like --function-naming-style=camelCase may be used in place of hand-written regular expressions. Default linter config enforce PEP8-compatible naming style. See documentation for details.

•   Raise meaningful exception in case of invalid reporter class (output format) being selected.

•   The docparams extension now allows a property docstring to document both the property and the setter. Therefore setters can also have no docstring.

•   The docparams extension now understands property type syntax.

    class Foo(object):
        @property
        def foo(self):
            """My Sphinx style docstring description.
            :type: int
            """
            return 10

    class Foo(object):
        @property
        def foo(self):
            """int: My Numpy and Google docstring style description."""
            return 10

•   In case of --output-format=json, the dictionary returned holds a new key-value pair. The key is message-id and the value the message id.

•   Spelling checker has a new configuration parameter max-spelling-suggestions, which affects maximum count of suggestions included in emitted message.

•   The invalid-name check contains the name of the template that caused the failure.

    For the given code, pylint used to emit invalid-name in the form Invalid constant name var, without offering any context why var is not such a good name.

    With this change, it is now more clear what should be improved for a name to be accepted according to its corresponding template.

•   New configuration flag, suggestion-mode was introduced. When enabled, pylint would attempt to emit user-friendly suggestions instead of spurious errors for some known false-positive scenarios. Flag is enabled by default.

•   superfluous-parens is no longer wrongly emitted for logical statements involving in operator (see example below for what used to be false-positive).

    foo = None
    if 'bar' in (foo or {}):
      pass

•   Redefinition of dummy function is now possible. function-redefined message won't be emitted anymore when dummy functions are redefined.

•   missing-param-doc and missing-type-doc are no longer emitted when Args and Keyword Args are mixed in Google docstring.

•   Fix of false positive useless-super-delegation message when parameters default values are different from those used in the base class.

•   Fix of false positive useless-else-on-loop message when break statements are deeply nested inside loop.

•   The Python 3 porting checker no longer emits multiple no-absolute-import per file.

•   The Python 3 porting checker respects disabled checkers found in the config file.

•   Modules, classes, or methods consist of compound statements that exceed the docstring-min-length are now correctly emitting missing-docstring

•   Fix no wrong-import-order message emitted on ordering of first and third party libraries. With this fix, pylint distinguishes first and third party modules when checking import order.

•   Fix the ignored pylint disable=fixme directives for comments following the last statement in a file.

•   Fix line-too-long message deactivated by wrong disable directive. The directive disable=fixme doesn't deactivate anymore the emission of line-too-long message for long commented lines.

•   If the rcfile specified on the command line doesn't exist, then an IOError exception is raised.

•   Fix the wrong scope of disable= directive after a commented line. For example when a disable=line-too-long directive is at the end of a long commented line, it no longer disables the emission of line-too-long message for lines that follow.

  What's New In Pylint 1.7

Release
    1.7

Date
    2017-04-13

  Summary -- Release highlights

•   None yet.

  New checkers

•   single-string-used-for-slots check was added, which is used whenever a class is using a single string as a slot value. While this is technically not a problem per se, it might trip users when manipulating the slots value as an iterable, which would in turn iterate over characters of the slot value. In order to be more straight-forward, always try to use a container such as a list or a tuple for defining slot values.

•   We added a new check, literal-comparison, which is used whenever pylint can detect a comparison to a literal. This is usually not what we want and, potentially, error prone. For instance, in the given example, the first string comparison returns true, since smaller strings are interned by the interpreter, while for larger ones, it will return False:

    mystring = "ok"
    if mystring is "ok": # Returns true
        # do stuff
    mystring = "a" * 1000
    if mystring is ("a" * 1000): # This will return False
        # do stuff

    Instead of using the is operator, you should use the == operator for this use case.

•   We added a new refactoring message, consider-merging-isinstance, which is emitted whenever we can detect that consecutive isinstance calls can be merged together. For instance, in this example, we can merge the first two isinstance calls:

    # $ cat a.py
    if isinstance(x, int) or isinstance(x, float):
        pass
    if isinstance(x, (int, float)) or isinstance(x, str):
        pass
    # $ pylint a.py
    # R:  1, 0: Consider merging these isinstance calls to isinstance(x, (float, int)) (consider-merging-isinstance)
    # R:  3, 0: Consider merging these isinstance calls to isinstance(x, (int, float, str)) (consider-merging-isinstance)

•   A new error check was added, invalid-metaclass, which is used whenever pylint can detect that a given class is using a metaclass which is invalid for the purpose of the class. This usually might indicate a problem in the code, rather than something done on purpose.

    # Needs to inherit from *type* in order to be valid
    class SomeClass(object):
        ...
    class MyClass(metaclass=SomeClass):
        pass

•   A new warning was added, useless-super-delegation, which is used whenever we can detect that an overridden method is useless, relying on super() delegation to do the same thing as another method from the MRO.

    For instance, in this example, the first two methods are useless, since they do the exact same thing as the methods from the base classes, while the next two methods are not, since they do some extra operations with the passed arguments.

    class Impl(Base):
        def __init__(self, param1, param2):
            super(Impl, self).__init__(param1, param2)
        def useless(self, first, second):
            return super(Impl, self).useless(first, second)
        def not_useless(self, first, **kwargs):
            debug = kwargs.pop('debug', False)
            if debug:
                ...
            return super(Impl, self).not_useless(first, **kwargs)
        def not_useless_1(self, first, *args):
            return super(Impl, self).not_useless_1(first + some_value, *args)

•   A new warning was added, len-as-condition, which is used whenever we detect that a condition uses len(SEQUENCE) incorrectly. Instead one could use if SEQUENCE or if not SEQUENCE.

    For instance, all of the examples below:

    if len(S):
      pass
    if not len(S):
      pass
    if len(S) > 0:
      pass
    if len(S) != 0:
      pass
    if len(S) == 0:
      pass

    can be written in a more natural way:

    if S:
      pass
    if not S:
      pass

    See https://www.python.org/dev/peps/pep-0008/#programming-recommendations for more information.

•   A new extension was added, emptystring.py which detects whenever we detect comparisons to empty string constants. This extension is disabled by default. For instance, the examples below:

    if S != "":
      pass
    if S == '':
      pass

    can be written in a more natural way:

    if S:
      pass
    if not S:
      pass

    An exception to this is when empty string is an allowed value whose meaning is treated differently than None. For example the meaning could be user selected no additional options vs. user has not made their selection yet!

    You can activate this checker by adding the line:

    load-plugins=pylint.extensions.emptystring

    to the MASTER section of your .pylintrc or using the command:

    $ pylint a.py --load-plugins=pylint.extensions.emptystring

•   A new extension was added, comparetozero.py which detects whenever we compare integers to zero. This extension is disabled by default. For instance, the examples below:

    if X != 0:
      pass
    if X == 0:
      pass

    can be written in a more natural way:

    if X:
      pass
    if not X:
      pass

    An exception to this is when zero is an allowed value whose meaning is treated differently than None. For example the meaning could be None means no limit, while 0 means the limit it zero!

    You can activate this checker by adding the line:

    load-plugins=pylint.extensions.comparetozero

    to the MASTER section of your .pylintrc or using the command:

    $ pylint a.py --load-plugins=pylint.extensions.comparetozero

•   We've added new error conditions for bad-super-call which now detect the usage of super(type(self), self) and super(self.__class__, self) patterns. These can lead to recursion loop in derived classes. The problem is visible only if you override a class that uses these incorrect invocations of super().

    For instance, Derived.__init__() will correctly call Base.__init__. At this point type(self) will be equal to Derived and the call again goes to Base.__init__ and we enter a recursion loop.

    class Base(object):
        def __init__(self, param1, param2):
            super(type(self), self).__init__(param1, param2)
    class Derived(Base):
        def __init__(self, param1, param2):
            super(Derived, self).__init__(param1, param2)

•   The warnings missing-returns-doc and missing-yields-doc have each been replaced with two new warnings - missing-[return|yield]-doc and missing-[return|yield]-type-doc. Having these as separate warnings allows the user to choose whether their documentation style requires text descriptions of function return/yield, specification of return/yield types, or both.

    # This will raise missing-return-type-doc but not missing-return-doc
    def my_sphinx_style_func(self):
        """This is a Sphinx-style docstring.
        :returns: Always False
        """
        return False
    # This will raise missing-return-doc but not missing-return-type-doc
    def my_google_style_func(self):
        """This is a Google-style docstring.
        Returns:
            bool:
        """
        return False

•   A new refactoring check was added, redefined-argument-from-local, which is emitted when pylint can detect than a function argument is redefined locally in some potential error prone cases. For instance, in the following piece of code, we have a bug, since the check will never return True, given the fact that we are comparing the same object to its attributes.

    def test(resource):
        for resource in resources:
            # The ``for`` is reusing ``resource``, which means that the following
            # ``resource`` is not what we wanted to check against.
            if resource.resource_type == resource:
               call_resource(resource)

    Other places where this check looks are with statement name bindings and except handler's name binding.

•   A new refactoring check was added, no-else-return, which is emitted when pylint encounters an else following a chain of ifs, all of them containing a return statement.

    def foo1(x, y, z):
        if x:
            return y
        else:  # This is unnecessary here.
            return z

    We could fix it deleting the else statement.

    def foo1(x, y, z):
        if x:
            return y
        return z

•   A new Python 3 check was added, eq-without-hash, which enforces classes that implement __eq__ also implement __hash__. The behavior around classes which implement __eq__ but not __hash__ changed in Python 3; in Python 2 such classes would get object.__hash__ as their default implementation. In Python 3, aforementioned classes get None as their implementation thus making them unhashable.

    class JustEq(object):
       def __init__(self, x):
         self.x = x
       def __eq__(self, other):
         return self.x == other.x
    class Neither(object):
      def __init__(self, x):
        self.x = x
    class HashAndEq(object):
       def __init__(self, x):
         self.x = x
       def __eq__(self, other):
         return self.x == other.x
       def __hash__(self):
         return hash(self.x)
    {Neither(1), Neither(2)}  # OK in Python 2 and Python 3
    {HashAndEq(1), HashAndEq(2)}  # OK in Python 2 and Python 3
    {JustEq(1), JustEq(2)}  # Works in Python 2, throws in Python 3

    In general, this is a poor practice which motivated the behavior change.

    as_set = {JustEq(1), JustEq(2)}
    print(JustEq(1) in as_set)  # prints False
    print(JustEq(1) in list(as_set))  # prints True

    In order to fix this error and avoid behavior differences between Python 2 and Python 3, classes should either explicitly set __hash__ to None or implement a hashing function.

    class JustEq(object):
       def __init__(self, x):
         self.x = x
       def __eq__(self, other):
         return self.x == other.x
       __hash__ = None
    {JustEq(1), JustEq(2)}  # Now throws an exception in both Python 2 and Python 3.

•   3 new Python 3 checkers were added, div-method, idiv-method and rdiv-method. The magic methods __div__ and __idiv__ have been phased out in Python 3 in favor of __truediv__. Classes implementing __div__ that still need to be used from Python 2 code not using from __future__ import division should implement __truediv__ and alias __div__ to that implementation.

    from __future__ import division
    class DivisibleThing(object):
       def __init__(self, x):
         self.x = x
       def __truediv__(self, other):
         return DivisibleThing(self.x / other.x)
       __div__ = __truediv__

•   A new Python 3 checker was added to warn about accessing the message attribute on Exceptions. The message attribute was deprecated in Python 2.7 and was removed in Python 3. See https://www.python.org/dev/peps/pep-0352/#retracted-ideas for more information.

    try:
      raise Exception("Oh No!!")
    except Exception as e:
      print(e.message)

    Instead of relying on the message attribute, you should explicitly cast the exception to a string:

    try:
      raise Exception("Oh No!!")
    except Exception as e:
      print(str(e))

•   A new Python 3 checker was added to warn about using encode or decode on strings with non-text codecs. This check also checks calls to open with the keyword argument encoding. See https://docs.python.org/3/whatsnew/3.4.html#improvements-to-codec-handling for more information.

    'hello world'.encode('hex')

    Instead of using the encode method for non-text codecs use the codecs module.

    import codecs
    codecs.encode('hello world', 'hex')

•   A new warning was added, overlapping-except, which is emitted when an except handler treats two exceptions which are overlapping. This means that one exception is an ancestor of the other one or it is just an alias.

    For example, in Python 3.3+, IOError is an alias for OSError. In addition, socket.error is an alias for OSError. The intention is to find cases like the following:

    import socket
    try:
        pass
    except (ConnectionError, IOError, OSError, socket.error):
        pass

•   A new Python 3 checker was added to warn about accessing sys.maxint. This attribute was removed in Python 3 in favor of sys.maxsize.

    import sys
    print(sys.maxint)

    Instead of using sys.maxint, use sys.maxsize

    import sys
    print(sys.maxsize)

•   A new Python 3 checker was added to warn about importing modules that have either moved or been removed from the standard library.

    One of the major undertakings with Python 3 was a reorganization of the standard library to remove old or supplanted modules and reorganize some of the existing modules. As a result, roughly 100 modules that exist in Python 2 no longer exist in Python 3. See https://www.python.org/dev/peps/pep-3108/ and https://www.python.org/dev/peps/pep-0004/ for more information. For suggestions on how to handle this, see https://pythonhosted.org/six/#module-six.moves or http://python3porting.com/stdlib.html.

    from cStringIO import StringIO

    Instead of directly importing the deprecated module, either use six.moves or a conditional import.

    from six.moves import cStringIO as StringIO
    if sys.version_info[0] >= 3:
        from io import StringIO
    else:
        from cStringIO import StringIO

    This checker will assume any imports that happen within a conditional or a try/except block are valid.

•   A new Python 3 checker was added to warn about accessing deprecated functions on the string module. Python 3 removed functions that were duplicated from the builtin str class. See https://docs.python.org/2/library/string.html#deprecated-string-functions for more information.

    import string
    print(string.upper('hello world!'))

    Instead of using string.upper, call the upper method directly on the string object.

    "hello world!".upper()

•   A new Python 3 checker was added to warn about calling str.translate with the removed deletechars parameter. str.translate is frequently used as a way to remove characters from a string.

    'hello world'.translate(None, 'low')

    Unfortunately, there is not an idiomatic way of writing this call in a 2and3 compatible way. If this code is not in the critical path for your application and the use of translate was a premature optimization, consider using re.sub instead:

    import re
    chars_to_remove = re.compile('[low]')
    chars_to_remove.sub('', 'hello world')

    If this code is in your critical path and must be as fast as possible, consider declaring a helper method that varies based upon Python version.

    if six.PY3:
        def _remove_characters(text, deletechars):
            return text.translate({ord(x): None for x in deletechars})
    else:
        def _remove_characters(text, deletechars):
            return text.translate(None, deletechars)

•   A new refactoring check was added, consider-using-ternary, which is emitted when pylint encounters constructs which were used to emulate ternary statement before it was introduced in Python 2.5.

    value = condition and truth_value or false_value

    Warning can be fixed by using standard ternary construct:

    value = truth_value if condition else false_value

•   A new refactoring check was added, trailing-comma-tuple, which is emitted when pylint finds an one-element tuple, created by a stray comma. This can suggest a potential problem in the code and it is recommended to use parentheses in order to emphasise the creation of a tuple, rather than relying on the comma itself.

    The warning is emitted for such a construct:

    a = 1,

    The warning can be fixed by adding parentheses:

    a = (1, )

•   Two new check were added for detecting an unsupported operation over an instance, unsupported-assignment-operation and unsupported-delete-operation. The first one is emitted whenever an object does not support item assignment, while the second is emitted when an object does not support item deletion:

    class A:
        pass
    instance = A()
    instance[4] = 4 # unsupported-assignment-operation
    del instance[4] # unsupported-delete-operation

•   A new check was added, relative-beyond-top-level, which is emitted when a relative import tries to access too many levels in the current package.

•   A new check was added, trailing-newlines, which is emitted when a file has trailing new lines.

•   invalid-length-returned check was added, which is emitted when a __len__ implementation does not return a non-negative integer.

•   There is a new extension, pylint.extensions.mccabe, which can be used for computing the McCabe complexity of classes and functions.

    You can enable this extension through --load-plugins=pylint.extensions.mccabe

•   A new check was added, used-prior-global-declaration. This is emitted when a name is used prior a global declaration, resulting in a SyntaxError in Python 3.6.

•   A new message was added, assign-to-new-keyword. This is emitted when used name is known to become a keyword in future Python release. Assignments to keywords would result in SyntaxError after switching to newer interpreter version.

    # While it's correct in Python 2.x, it raises a SyntaxError in Python 3.x
    True = 1
    False = 0
    # Same as above, but it'll be a SyntaxError starting from Python 3.7
    async = "async"
    await = "await

  Other Changes

•   We don't emit by default no-member if we have opaque inference objects in the inference results

    This is controlled through the new flag --ignore-on-opaque-inference, which is by default True. The inference can return multiple potential results while evaluating a Python object, but some branches might not be evaluated, which results in partial inference. In that case, it might be useful to still emit no-member and other checks for the rest of the inferred objects.

•   Namespace packages are now supported by pylint. This includes both explicit namespace packages and implicit namespace packages, supported in Python 3 through PEP 420.

•   A new option was added, --analyse-fallback-block.

    This can be used to support both Python 2 and 3 compatible import block code, which means that the import block might have code that exists only in one or another interpreter, leading to false positives when analysed. By default, this is false, you can enable the analysis for both branches using this flag.

•   ignored-argument-names option is now used for ignoring arguments for unused-variable check.

    This option was used for ignoring arguments when computing the correct number of arguments a function should have, but for handling the arguments with regard to unused-variable check, dummy-variables-rgx was used instead. Now, ignored-argument-names is used for its original purpose and also for ignoring the matched arguments for the unused-variable check. This offers a better control of what should be ignored and how. Also, the same option was moved from the design checker to the variables checker, which means that the option now appears under the [VARIABLES] section inside the configuration file.

•   A new option was added, redefining-builtins-modules, for controlling the modules which can redefine builtins, such as six.moves and future.builtins.

•   A new option was added, ignore-patterns, which is used for building a ignore list of directories and files matching the regex patterns, similar to the ignore option.

•   The reports are now disabled by default, as well as the information category warnings.

•   arguments-differ check was rewritten to take in consideration keyword only parameters and variadics.

    Now it also complains about losing or adding capabilities to a method, by introducing positional or keyword variadics. For instance, pylint now complains about these cases:

    class Parent(object):
        def foo(self, first, second):
            ...
        def bar(self, **kwargs):
            ...
        def baz(self, *, first):
            ...
    class Child(Parent):
        # Why subclassing in the first place?
        def foo(self, *args, **kwargs):
            # mutate args or kwargs.
            super(Child, self).foo(*args, **kwargs)
        def bar(self, first=None, second=None, **kwargs):
            # The overridden method adds two new parameters,
            # which can also be passed as positional arguments,
            # breaking the contract of the parent's method.
        def baz(self, first):
            # Not keyword-only

•   redefined-outer-name is now also emitted when a nested loop's target variable is the same as an outer loop.

    for i, j in [(1, 2), (3, 4)]:
        for j in range(i):
            print(j)

•   relax character limit for method and function names that starts with _. This will let people to use longer descriptive names for methods and functions with a shorter scope (considered as private). The same idea applies to variable names, only with an inverse rule: you want long descriptive names for variables with bigger scope, like globals.

•   Add InvalidMessageError exception class and replace assert in pylint.utils with raise InvalidMessageError.

•   UnknownMessageError (formerly UnknownMessage) and EmptyReportError (formerly EmptyReport) are now provided by the new pylint.exceptions submodule instead of pylint.utils as before.

•   We now support inline comments for comma separated values in the configurations

    For instance, you can now use the # sign for having comments inside comma separated values, as seen below:

    disable=no-member, # Don't care about it for now
            bad-indentation, # No need for this
            import-error

    Of course, interweaving comments with values is also working:

    disable=no-member,
            # Don't care about it for now
            bad-indentation # No need for this

    This works by setting the inline comment prefixes accordingly.

•   Added epytext docstring support to the docparams extension.

•   We added support for providing hints when not finding a missing member.

    For example, given the following code, it should be obvious that the programmer intended to use the mail attribute, rather than email.

    class Contribution:
        def __init__(self, name, email, date):
            self.name = name
            self.mail = mail
            self.date = date
    for c in contributions:
        print(c.email) # Oups

    pylint will now warn that there is a chance of having a typo, suggesting new names that could be used instead.

    $ pylint a.py
    E: 8,10: Instance of 'Contribution' has no 'email' member; maybe 'mail'?

    The behaviour is controlled through the --missing-member-hint option. Other options that come with this change are --missing-member-max-choices for choosing the total number of choices that should be picked in this situation and --missing-member-hint-distance, which specifies a metric for computing the distance between the names (this is based on Levenshtein distance, which means the lower the number, the more pickier the algorithm will be).

•   PyLinter.should_analyze_file has a new parameter, is_argument, which specifies if the given path is a pylint argument or not.

    should_analyze_file is called whenever pylint tries to determine if a file should be analyzed, defaulting to files with the .py extension, but this function gets called only in the case where the said file is not passed as a command line argument to pylint. This usually means that pylint will analyze a file, even if that file has a different extension, as long as the file was explicitly passed at command line. Since should_analyze_file cannot be overridden to handle all the cases, the check for the provenience of files was moved into should_analyze_file. This means we now can write something similar with this example, for ignoring every file respecting the desired property, disregarding the provenience of the file, being it a file passed as CLI argument or part of a package.

    from pylint.lint import Run, PyLinter
    class CustomPyLinter(PyLinter):
         def should_analyze_file(self, modname, path, is_argument=False):
             if respect_condition(path):
                 return False
             return super().should_analyze_file(modname, path, is_argument=is_argument)
    class CustomRun(Run):
         LinterClass = CustomPyLinter
    CustomRun(sys.argv[1:])

•   Imports aliased with underscore are skipped when checking for unused imports.

•   bad-builtin and redefined-variable-type are now extensions, being disabled by default. They can be enabled through: --load-plugins=pylint.extensions.redefined_variable_type,pylint.extensions.bad_builtin

•   Imports checker supports new switch allow-wildcard-with-all which disables warning on wildcard import when imported module defines __all__ variable.

•   differing-param-doc is now used for the differing part of the old missing-param-doc, and differing-type-doc for the differing part of the old missing-type-doc.

  Bug fixes

•   Fix a false positive of redundant-returns-doc, occurred when the documented function was using yield instead of return.

•   Fix a false positive of missing-param-doc and missing-type-doc, occurred when a class docstring uses the For the parameters, see magic string but the class __init__ docstring does not, or vice versa.

•   Added proper exception type inference for missing-raises-doc. Now:

    def my_func():
        """"My function."""
        ex = ValueError('foo')
        raise ex

    will properly be flagged for missing documentation of :raises ValueError: instead of :raises ex:, among other scenarios.

•   Fix false positives of missing-[raises|params|type]-doc due to not recognizing valid keyword synonyms supported by Sphinx.

•   More thorough validation in MessagesStore.register_messages() to detect conflicts between a new message and any existing message id, symbol, or old_names.

•   We now support having plugins that shares the same name and with each one providing options.

    A plugin can be logically split into multiple classes, each class providing certain capabilities, all of them being tied under the same name. But when two or more such classes are also adding options, then pylint crashed, since it already added the first encountered section. Now, these should work as expected.

    from pylint.checkers import BaseChecker
    class DummyPlugin1(BaseChecker):
        name = 'dummy_plugin'
        msgs = {'I9061': ('Dummy short desc 01', 'dummy-message-01', 'Dummy long desc')}
        options = (
            ('dummy_option_1', {
                'type': 'string',
                'metavar': '<string>',
                'help': 'Dummy option 1',
            }),
        )
    class DummyPlugin2(BaseChecker):
        name = 'dummy_plugin'
        msgs = {'I9060': ('Dummy short desc 02', 'dummy-message-02', 'Dummy long desc')}
        options = (
            ('dummy_option_2', {
                'type': 'string',
                'metavar': '<string>',
                'help': 'Dummy option 2',
            }),
        )
    def register(linter):
        linter.register_checker(DummyPlugin1(linter))
        linter.register_checker(DummyPlugin2(linter))

•   We do not yield unused-argument for singledispatch implementations and do not warn about function-redefined for multiple implementations with same name.

    from functools import singledispatch
    @singledispatch
    def f(x):
        return 2*x
    @f.register(str)
    def _(x):
        return -1
    @f.register(int)
    @f.register(float)
    def _(x):
        return -x

•   unused-variable checker has new functionality of warning about unused variables in global module namespace. Since globals in module namespace may be a part of exposed API, this check is disabled by default. For enabling it, set allow-global-unused-variables option to false.

•   Fix a false-positive logging-format-interpolation message, when format specifications are used in formatted string. In general, these operations are not always convertible to old-style formatting used by logging module.

•   Added a new switch single-line-class-stmt to allow single-line declaration of empty class bodies (as seen in the example below). Pylint won't emit a multiple-statements message when this option is enabled.

    class MyError(Exception): pass

•   too-many-format-args and too-few-format-args are emitted correctly (or not emitted at all, when exact count of elements in RHS cannot be inferred) when starred expressions are used in RHS tuple. For example, code block as shown below detects correctly that the used tuple has in fact three elements, not two.

    meat = ['spam', 'ham']
    print('%s%s%s' % ('eggs', *meat))

•   cyclic-import checker supports local disable clauses. When one of cycle imports was done in scope where disable clause was active, cycle is not reported as violation.

  Removed Changes

•   pylint-gui was removed, because it was deemed unfit for being included in pylint. It had a couple of bugs and misfeatures, its usability was subpar and since its development was neglected, we decided it is best to move on without it.

•   The HTML reporter was removed, including the --output-format=html option. It was lately a second class citizen in Pylint, being mostly neglected. Since we now have the JSON reporter, it can be used as a basis for building more prettier HTML reports than what Pylint can currently generate. This is part of the effort of removing cruft from Pylint, by removing less used features.

•   The --files-output option was removed. While the same functionality cannot be easily replicated, the JSON reporter, for instance, can be used as a basis for generating the messages per each file.

•   --required-attributes option was removed.

•   --ignore-iface-methods option was removed.

•   The --optimize-ast flag was removed.

    The option was initially added for handling pathological cases, such as joining too many strings using the addition operator, which was leading pylint to have a recursion error when trying to figure out what the string was. Unfortunately, we decided to ignore the issue, since the pathological case would have happen when the code was parsed by Python as well, without actually reaching the runtime step and as such, we decided to remove the error altogether.

•   epylint.py_run's script parameter was removed.

    Now epylint.py_run is always using the underlying epylint.lint method from the current interpreter. This avoids some issues when multiple instances of pylint are installed, which means that epylint.py_run might have ran a different epylint script than what was intended.

  What's New In Pylint 1.6

Release
    1.6.0

Date
    2016-07-07

  Summary -- Release highlights

Nothing major.

  New checkers

•   We added a new recommendation check, consider-iterating-dictionary, which is emitted when a dictionary is iterated by using .keys().

    For instance, the following code would trigger this warning, since the dictionary's keys can be iterated without calling the method explicitly.

    for key in dictionary.keys():
        ...
    # Can be refactored to:
    for key in dictionary:
        ...

•   trailing-newlines check was added, which is emitted when a file has trailing newlines.

•   invalid-length-returned check was added, which is emitted when the __len__ special method returns something else than a non-negative number. For instance, this example is triggering it:

    class Container(object):
        def __len__(self):
            return self._items # Oups, forgot to call len() over it.

•   Add a new check to the check_docs extension for looking for duplicate constructor parameters in a class constructor docstring or in a class docstring.

    The check multiple-constructor-doc is emitted when the parameter is documented in both places.

•   We added a new extension plugin, pylint.extensions.mccabe, which can be used for warning about the complexity in the code.

    You can enable it as in:

    $ pylint module_or_project --load-plugins=pylint.extensions.mccabe

    See more at pylint.extensions.mccabe

  New features

•   generated-members now supports qualified names through regular expressions.

    For instance, for ignoring all the errors generated by numpy.core's attributes, we can now use:

    $ pylint a.py --generated-members=numpy.*

•   Add the ability to ignore files based on regex matching, with the new --ignore-patterns option.

    Rather than clobber the existing ignore option, we decided to have a separate option for it. For instance, for ignoring all the test files, we can now use:

    $ pylint myproject --ignore-patterns=test.*?py

•   We added a new option, redefining-builtins-modules, which is used for defining the modules which can redefine builtins. pylint will emit an error when a builtin is redefined, such as defining a variable called next. But in some cases, the builtins can be redefined in the case they are imported from other places, different than the builtins module, such is the case for six.moves, which contains more forward-looking functions:

    $ cat a.py
    # Oups, now pylint emits a redefined-builtin message.
    from six.moves import open
    $ pylint a.py --redefining-builtins-modules=six.moves

    Default values: six.moves,future.builtins

  Bug fixes

•   Fixed a bug where the top name of a qualified import was detected as an unused variable.

•   We don't warn about invalid-sequence-index if the indexed object has unknown base classes, that Pylint cannot deduce.

  Other Changes

•   The bad-builtin check was moved into an extension.

    The check was complaining about used builtin functions which were supposed to not be used. For instance, map and filter were falling into this category, since better alternatives can be used, such as list comprehensions. But the check was annoying, since using map or filter can have its use cases and as such, we decided to move it to an extension check instead. It can now be enabled through --load-plugins=pylint.extensions.bad_builtin.

•   We use the configparser backport internally, for Python 2.

    This allows having comments inside list values, in the configuration, such as:

    disable=no-member,
            # Don't like this check
            bad-indentation

•   We now use the isort package internally.

    This improves the `wrong-import-order check, so now we should have less false positives regarding the import order.

•   We do not emit import-error or no-name-in-module for fallback import blocks by default.

    A fallback import block can be considered a TryExcept block, which contains imports in both branches, such as:

    try:
        import urllib.request as request
    except ImportError:
        import urllib2 as request

    In the case where pylint can not find one import from the except branch, then it will emit an import-error, but this gets cumbersome when trying to write compatible code for both Python versions. As such, we don't check these blocks by default, but the analysis can be enforced by using the new --analyse-fallback-block flag.

•   reimported is emitted when the same name is imported from different module, as in:

    from collections import deque, OrderedDict, deque

  Deprecated features

•   The HTML support was deprecated and will be eventually removed in Pylint 1.7.0.

    This feature was lately a second class citizen in Pylint, being often neglected and having a couple of bugs. Since we now have the JSON reporter, this can be used as a basis for more prettier HTML outputs than what Pylint can currently offer.

•   The --files-output option was deprecated and will be eventually removed in Pylint 1.7.0.

•   The --optimize-ast option was deprecated and will be eventually removed in Pylint 1.7.0.

    The option was initially added for handling pathological cases, such as joining too many strings using the addition operator, which was leading pylint to have a recursion error when trying to figure out what the string was. Unfortunately, we decided to ignore the issue, since the pathological case would have happen when the code was parsed by Python as well, without actually reaching the runtime step and as such, we will remove the option in the future.

•   The check_docs extension is now deprecated. The extension is still available under the docparams name, so this should work:

    $ pylint module_or_package --load-extensions=pylint.extensions.docparams

    The old name is still kept for backward compatibility, but it will be eventually removed.

  Removed features

•   None yet

    The "Changelog" contains all nontrivial changes to Pylint for the current version.

  Pylint's ChangeLog

  What's New in Pylint 2.13.0?

Release date: TBA

  What's New in Pylint 2.12.3?

Release date: TBA

  What's New in Pylint 2.12.2?

Release date: 2021-11-25

•   Fixed a false positive for unused-import where everything was not analyzed properly inside typing guards.

•   Fixed a false-positive regression for used-before-assignment for typed variables in the body of class methods that reference the same class

    Closes #5342

•   Specified that the ignore-paths option considers "" to represent a windows directory delimiter instead of a regular expression escape character.

•   Fixed a crash with the ignore-paths option when invoking the option via the command line.

    Closes #5437

•   Fixed handling of Sphinx-style parameter docstrings with asterisks. These should be escaped with by prepending a "".

    Closes #5406

•   Add endLine and endColumn keys to output of JSONReporter.

    Closes #5380

•   Fixed handling of Google-style parameter specifications where descriptions are on the line following the parameter name. These were generating false positives for missing-param-doc.

    Closes #5452

•   Fix false negative for consider-iterating-dictionary during membership checks encapsulated in iterables or not in checks

    Closes #5323

•   unused-import now check all ancestors for typing guards

    Closes #5316

  What's New in Pylint 2.12.1?

Release date: 2021-11-25

•   Require Python 3.6.2 to run pylint.

    Closes #5065

  What's New in Pylint 2.12.0?

Release date: 2021-11-24

•   Upgrade astroid to 2.9.0

    Closes #4982

•   Add ability to add end_line and end_column to the --msg-template option. With the standard TextReporter this will add the line and column number of the end of a node to the output of Pylint. If these numbers are unknown, they are represented by an empty string.

•   Introduced primer tests and a configuration tests framework. The helper classes available in pylint/testutil/ are still unstable and might be modified in the near future.

    Closes #4412 #5287

•   Fix install graphiz message which isn't needed for puml output format.

•   MessageTest of the unittest testutil now requires the confidence attribute to match the expected value. If none is provided it is set to UNDEFINED.

•   add_message of the unittest testutil now actually handles the col_offset parameter and allows it to be checked against actual output in a test.

•   Fix a crash in the check_elif extensions where an undetected if in a comprehension with an if statement within a f-string resulted in an out of range error. The checker no longer relies on counting if statements anymore and uses known if statements locations instead. It should not crash on badly parsed if statements anymore.

•   Fix simplify-boolean-expression when condition can be inferred as False.

    Closes #5200

•   Fix exception when pyreverse parses property function of a class.

•   The functional testutils now accept end_lineno and end_column. Expected output files without these will trigger a DeprecationWarning. Expected output files can be easily updated with the python tests/test_functional.py --update-functional-output command.

•   The functional testutils now correctly check the distinction betweeen HIGH and UNDEFINED confidence. Expected output files without defiend confidence levels will now trigger a DeprecationWarning. Expected output files can be easily updated with the python tests/test_functional.py --update-functional-output command.

•   The functional test runner now supports the option min_pyver_end_position to control on which python versions the end_lineno and end_column attributes should be checked. The default value is 3.8.

•   Fix accept-no-yields-doc and accept-no-return-doc not allowing missing yield or return documentation when a docstring is partially correct

    Closes #5223

•   Add an optional extension consider-using-any-or-all : Emitted when a for loop only produces a boolean and could be replaced by any or all using a generator. Also suggests a suitable any or all statement.

    Closes #5008

•   Properly identify parameters with no documentation and add new message called missing-any-param-doc

    Closes #3799

•   Add checkers overridden-final-method & subclassed-final-class

    Closes #3197

•   Fixed protected-access for accessing of attributes and methods of inner classes

    Closes #3066

•   Added support for ModuleNotFoundError (import-error and no-name-in-module). ModuleNotFoundError inherits from ImportError and was added in Python 3.6

•   undefined-variable now correctly flags variables which only receive a type annotations and never get assigned a value

    Closes #5140

•   undefined-variable now correctly considers the line numbering and order of classes used in metaclass declarations

    Closes #4031

•   used-before-assignment now correctly considers references to classes as type annotation or default values in first-level methods

    Closes #3771

•   undefined-variable and unused-variable now correctly trigger for assignment expressions in functions defaults

    Fixes part of #3688

•   undefined-variable now correctly triggers for assignment expressions in if ... else statements This includes a basic form of control flow inference for if ... else statements using constant boolean values

    Closes #3688

•   Added the --enable-all-extensions command line option. It will load all available extensions which can be listed by running --list-extensions

•   Fix bug with importing namespace packages with relative imports

    Closes #2967 and #5131

•   Improve and flatten unused-wildcard-import message

    Closes #3859

•   In length checker, len-as-condition has been renamed as use-implicit-booleaness-not-len in order to be consistent with use-implicit-booleaness-not-comparison.

•   Created new UnsupportedVersionChecker checker class that includes checks for features not supported by all versions indicated by a py-version.

•   Added using-f-string-in-unsupported-version checker. Issued when py-version is set to a version that does not support f-strings (< 3.6)

•   Fix useless-super-delegation false positive when default keyword argument is a variable.

•   Properly emit duplicate-key when Enum members are duplicate dictionary keys

    Closes #5150

•   Use py-version setting for alternative union syntax check (PEP 604), instead of the Python interpreter version.

•   Subclasses of dict are regarded as reversible by the bad-reversed-sequence checker (Python 3.8 onwards).

    Closes #4981

•   Support configuring mixin class pattern via mixin-class-rgx

•   Added new checker use-implicit-booleaness-not-comparison: Emitted when collection literal comparison is being used to check for emptiness.

    Closes #4774

•   mising-param-doc now correctly parses asterisks for variable length and keyword parameters

    Closes #3733

•   mising-param-doc now correctly handles Numpy parameter documentation without explicit typing

    Closes #5222

•   pylint no longer crashes when checking assignment expressions within if-statements

    Closes #5178

•   Update literal-comparison` checker to ignore tuple literals

    Closes #3031

•   Normalize the input to the ignore-paths option to allow both Posix and Windows paths

    Closes #5194

•   Fix double emitting of not-callable on inferrable properties

    Closes #4426

•   self-cls-assignment now also considers tuple assignment

•   Fix missing-function-docstring not being able to check __init__ and other magic methods even if the no-docstring-rgx setting was set to do so

•   Added using-final-decorator-in-unsupported-version checker. Issued when py-version is set to a version that does not support typing.final (< 3.8)

•   Added configuration option exclude-too-few-public-methods to allow excluding classes from the min-public-methods checker.

    Closes #3370

•   The --jobs parameter now fallbacks to 1 if the host operating system does not have functioning shared semaphore implementation.

    Closes #5216

•   Fix crash for unused-private-member when checking private members on __class__

    Closes #5261

•   Crashes when a list is encountered in a toml configuration do not happen anymore.

    Closes #4580

•   Moved misplaced-comparison-constant to its own extension comparison_placement. This checker was opinionated and now no longer a default. It can be reactived by adding pylint.extensions.comparison_placement to load-plugins in your config.

    Closes #1064

•   A new bad-configuration-section checker was added that will emit for misplaced option in pylint's top level namespace for toml configuration. Top-level dictionaries or option defined in the wrong section will still silently not be taken into account, which is tracked in a follow-up issue.

    Follow-up in #5259

•   Fix crash for protected-access on (outer) class traversal

•   Added new checker useless-with-lock to find incorrect usage of with statement and threading module locks. Emitted when with threading.Lock(): is used instead of with lock_instance:.

    Closes #5208

•   Make yn validator case insensitive, to allow for True and False in config files.

•   Fix crash on open() calls when the mode argument is not a simple string.

    Partially closes #5321

•   Inheriting from a class that implements __class_getitem__ no longer raises inherit-non-class.

•   Pyreverse - Add the project root directory to sys.path

    Closes #2479

•   Don't emit consider-using-f-string if py-version is set to Python < 3.6. f-strings were added in Python 3.6

    Closes #5019

•   Fix regression for unspecified-encoding with pathlib.Path.read_text()

    Closes #5029

•   Don't emit consider-using-f-string if the variables to be interpolated include a backslash

•   Fixed false positive for cell-var-from-loop when variable is used as the default value for a keyword-only parameter.

    Closes #5012

•   Fix false-positive undefined-variable with Lambda, IfExp, and assignment expression.

•   Fix false-positive useless-suppression for wrong-import-order

    Closes #2366

•   Fixed toml dependency issue

    Closes #5066

•   Fix false-positive useless-suppression for line-too-long

    Closes #4212

•   Fixed invalid-name not checking parameters of overwritten base object methods

    Closes #3614

•   Fixed crash in consider-using-f-string if format is not called

    Closes #5058

•   Fix crash with AssignAttr in if TYPE_CHECKING blocks.

    Closes #5111

•   Improve node information for invalid-name on function argument.

•   Prevent return type checkers being called on functions with ellipses as body

    Closes #4736

•   Add is_sys_guard and is_typing_guard helper functions from astroid to pylint.checkers.utils.

•   Fix regression on ClassDef inference

    Closes #5030 Closes #5036

•   Fix regression on Compare node inference

    Closes #5048

•   Fix false-positive isinstance-second-argument-not-valid-type with typing.Callable.

    Closes #3507 Closes #5087

•   It is now recommended to do pylint development on Python 3.8 or higher. This allows using the latest ast parser.

•   All standard jobs in the pylint CI now run on Python 3.8 by default. We still support python 3.6 and 3.7 and run tests for those interpreters.

•   TypingChecker

•   Fix false-negative for deprecated-typing-alias and consider-using-alias with typing.Type + typing.Callable.

  What's New in Pylint 2.11.1?

Release date: 2021-09-16

•   unspecified-encoding now checks the encoding of pathlib.Path() correctly

    Closes #5017

  What's New in Pylint 2.11.0?

Release date: 2021-09-16

•   The python3 porting mode checker and it's py3k option were removed. You can still find it in older pylint versions.

•   raising-bad-type is now properly emitted when raising a string

•   Added new extension SetMembershipChecker with use-set-for-membership check: Emitted when using an in-place defined list or tuple to do a membership test. sets are better optimized for that.

    Closes #4776

•   Added py-version config key (if [MASTER] section). Used for version dependant checks. Will default to whatever Python version pylint is executed with.

•   CodeStyleChecker

•   Added consider-using-assignment-expr: Emitted when an assignment is directly followed by an if statement and both can be combined by using an assignment expression :=. Requires Python 3.8

    Closes #4862

•   Added consider-using-f-string: Emitted when .format() or '%' is being used to format a string.

    Closes #3592

•   Fix false positive for consider-using-with if a context manager is assigned to a variable in different paths of control flow (e. g. if-else clause).

    Closes #4751

•   https is now prefered in the documentation and http://pylint.pycqa.org correctly redirect to https://pylint.pycqa.org

    Closes #3802

•   Fix false positive for function-redefined for simple type annotations

    Closes #4936

•   Fix false positive for protected-access if a protected member is used in type hints of function definitions

•   Fix false positive dict-iter-missing-items for dictionaries only using tuples as keys

    Closes #3282

•   The unspecified-encoding checker now also checks calls to pathlib.Path().read_text() and pathlib.Path().write_text()

    Closes #4945

•   Fix false positive superfluous-parens for tuples created with inner tuples

    Closes #4907

•   Fix false positive unused-private-member for accessing attributes in a class using cls

    Closes #4849

•   Fix false positive unused-private-member for private staticmethods accessed in classmethods.

    Closes #4849

•   Extended consider-using-in check to work for attribute access.

•   Setting min-similarity-lines to 0 now makes the similarty checker stop checking for duplicate code

    Closes #4901

•   Fix a bug where pylint complained if the cache's parent directory does not exist

    Closes #4900

•   The global-variable-not-assigned checker now catches global variables that are never reassigned in a local scope and catches (reassigned) functions

    Closes #1375 Closes #330

•   Fix false positives for invalid-all-format that are lists or tuples at runtime

    Closes #4711

•   Fix no-self-use and docparams extension for async functions and methods.

•   Add documentation for pyreverse and symilar

    Closes #4616

•   Non symbolic messages with the wrong capitalisation now correctly trigger use-symbolic-message-instead

    Closes #5000

•   The consider-iterating-dictionary checker now also considers membership checks

    Closes #4069

•   The invalid-name message is now more detailed when using multiple naming style regexes.

  What's New in Pylint 2.10.2?

Release date: 2021-08-21

•   We now use platformdirs instead of appdirs since the latter is not maintained.

    Closes #4886

•   Fix a crash in the checker raising shallow-copy-environ when failing to infer on copy.copy

    Closes #4891

  What's New in Pylint 2.10.1?

Release date: 2021-08-20

•   pylint does not crash when PYLINT_HOME does not exist.

    Closes #4883

  What's New in Pylint 2.10.0?

Release date: 2021-08-20

•   pyreverse: add option to produce colored output.

    Closes #4488

•   pyreverse: add output in PlantUML format.

    Closes #4498

•   consider-using-with is no longer triggered if a context manager is returned from a function.

    Closes #4748

•   pylint does not crash with a traceback anymore when a file is problematic. It creates a template text file for opening an issue on the bug tracker instead. The linting can go on for other non problematic files instead of being impossible.

•   pyreverse: Show class has-a relationships inferred from the type-hint

    Closes #4744

•   Fixed a crash when importing beyond the top level package during import-error message creation

    Closes #4775

•   Added ignored-parents option to the design checker to ignore specific classes from the too-many-ancestors check (R0901).

    Partially closes #3057

•   Added unspecified-encoding: Emitted when open() is called without specifying an encoding

    Closes #3826

•   Improved the Similarity checker performance. Fix issue with --min-similarity-lines used with --jobs.

    Close #4120 Close #4118

•   Don't emit no-member error if guarded behind if statement.

    Ref #1162 Closes #1990 Closes #4168

•   The default for PYLINTHOME is now the standard XDG_CACHE_HOME, and pylint now uses appdirs.

    Closes #3878

•   Added use-list-literal: Emitted when list() is called with no arguments instead of using []

    Closes #4365

•   Added use-dict-literal: Emitted when dict() is called with no arguments instead of using {}

    Closes #4365

•   Added optional extension consider-ternary-expression: Emitted whenever a variable is assigned in both branches of an if/else block.

    Closes # 4366

•   Added optional extension while-used: Emitted whenever a while loop is used.

    Closes # 4367

•   Added forgotten-debug-statement: Emitted when breakpoint, pdb.set_trace or sys.breakpointhook calls are found

    Closes #3692

•   Fix false-positive of unused-private-member when using nested functions in a class

    Closes #4673

•   Fix crash for unused-private-member that occurred with nested attributes.

    Closes #4755

•   Fix a false positive for unused-private-member with class names

    Closes #4681

•   Fix false positives for superfluous-parens with walrus operator, ternary operator and inside list comprehension.

    Closes #2818 Closes #3249 Closes #3608 Closes #4346

•   Added format-string-without-interpolation checker: Emitted when formatting is applied to a string without any variables to be replaced

    Closes #4042

•   Refactor of --list-msgs & --list-msgs-enabled: both options now show whether messages are emittable with the current interpreter.

    Closes #4778

•   Fix false negative for used-before-assignment when the variable is assigned in an exception handler, but used outside of the handler.

    Closes #626

•   Added disable-next option: allows using # pylint: disable-next=msgid to disable a message for the following line

    Closes #1682

•   Added redundant-u-string-prefix checker: Emitted when the u prefix is added to a string

    Closes #4102

•   Fixed cell-var-from-loop checker: handle cell variables in comprehensions within functions, and function default argument expressions. Also handle basic variable shadowing.

    Closes #2846 Closes #3107

•   Fixed bug with cell-var-from-loop checker: it no longer has false negatives when both unused-variable and used-before-assignment are disabled.

•   Fix false postive for invalid-all-format if the list or tuple builtin functions are used

    Closes #4711

•   Config files can now contain environment variables

    Closes #3839

•   Fix false-positive used-before-assignment with an assignment expression in a Return node

    Closes #4828

•   Added use-sequence-for-iteration: Emitted when iterating over an in-place defined set.

•   CodeStyleChecker

•   Limit consider-using-tuple to be emitted only for in-place defined lists.

•   Emit consider-using-tuple even if list contains a starred expression.

•   Ignore decorators lines by similarities checker when ignore signatures flag enabled

    Closes #4839

•   Allow true and false values in pylintrc for better compatibility with toml config.

•   Class methods' signatures are ignored the same way as functions' with similarities "ignore-signatures" option enabled

    Closes #4653

•   Improve performance when inferring Call nodes, by utilizing caching.

•   Improve error message for invalid-metaclass when the node is an Instance.

  What's New in Pylint 2.9.6?

Release date: 2021-07-28

•   Fix a false positive undefined-variable when variable name in decoration matches function argument

    Closes #3791

  What's New in Pylint 2.9.5?

Release date: 2021-07-21

•   Fix a crash when there would be a 'TypeError object does not support item assignment' in the code we parse.

    Closes #4439

•   Fix crash if a callable returning a context manager was assigned to a list or dict item

    Closes #4732

•   Fix a crash when an AttributeInferenceError was not handled properly when failing to infer the real name of an import in astroid.

    Closes #4692

  What's New in Pylint 2.9.4?

Release date: 2021-07-20

•   Added time.clock to deprecated functions/methods for python 3.3

•   Fix bug in which --fail-on can return a zero exit code even when the specified issue is present

    Closes #4296 Closes #3363

•   Fix hard failure when handling missing attribute in a class with duplicated bases

    Closes #4687

•   Fix false-positive consider-using-with (R1732) if a ternary conditional is used together with with

    Closes #4676

•   Fix false-positive deprecated-module when relative import uses deprecated module name.

    Closes #4629

•   Fix false-positive consider-using-with (R1732) if contextlib.ExitStack takes care of calling the __exit__ method

    Closes #4654

•   Fix a false positive for unused-private-member when mutating a private attribute with cls

    Closes #4657

•   Fix ignored empty functions by similarities checker with "ignore-signatures" option enabled

    Closes #4652

•   Fix false-positive of use-maxsplit-arg when index is incremented in a loop

    Closes #4664

•   Don't emit cyclic-import message if import is guarded by typing.TYPE_CHECKING.

    Closes #3525

•   Fix false-positive not-callable with alternative TypedDict syntax

    Closes #4715

•   Clarify documentation for consider-using-from-import

•   Don't emit unreachable warning for empty generator functions

    Closes #4698

•   Don't emit import-error, no-name-in-module, and ungrouped-imports for imports guarded by sys.version_info or typing.TYPE_CHECKING.

    Closes #3285 Closes #3382

•   Fix invalid-overridden-method with nested property

    Closes #4368

•   Fix false-positive of unused-private-member when using __new__ in a class

    Closes #4668

•   No longer emit consider-using-with for ThreadPoolExecutor and ProcessPoolExecutor as they have legitimate use cases without a with block.

    Closes #4689

•   Fix crash when inferring variables assigned in match patterns

    Closes #4685

•   Fix a crash when a StopIteration was raised when inferring a faulty function in a context manager.

    Closes #4723

  What's New in Pylint 2.9.3?

Release date: 2021-07-01

•   Fix a crash that happened when analysing empty function with docstring in the similarity checker.

    Closes #4648

•   The similarity checker no longer add three trailing whitespaces for empty lines in its report.

  What's New in Pylint 2.9.2?

Release date: 2021-07-01

•   Fix a crash that happened when analysing code using type(self) to access a class attribute in the unused-private-member checker.

    Closes #4638

•   Fix a false positive for unused-private-member when accessing a private variable with self

    Closes #4644

•   Fix false-positive of unnecessary-dict-index-lookup and consider-using-dict-items for reassigned dict index lookups

    Closes #4630

  What's New in Pylint 2.9.1?

Release date: 2021-06-30

•   Upgrade astroid to 2.6.2

    Closes #4631 Closes #4633

  What's New in Pylint 2.9.0?

Release date: 2021-06-29

•   Python 3.10 is now supported.

•   Add type annotations to pyreverse dot files

    Closes #1548

•   Fix missing support for detecting deprecated aliases to existing functions/methods.

    Closes #4618

•   astroid has been upgraded to 2.6.1

•   Added various deprecated functions/methods for python 3.10, 3.7, 3.6 and 3.3

•   Fix false positive useless-type-doc on ignored argument using pylint.extensions.docparams when a function was typed using pep484 but not inside the docstring.

    Closes #4117 Closes #4593

•   setuptools_scm has been removed and replaced by tbump in order to not have hidden runtime dependencies to setuptools

•   Fix a crash when a test function is decorated with @pytest.fixture and astroid can't infer the name of the decorator when using open without with.

    Closes #4612

•   Added deprecated-decorator: Emitted when deprecated decorator is used.

    Closes #4429

•   Added ignore-paths behaviour. Defined regex patterns are matched against full file path.

    Close #2541

•   Fix false negative for consider-using-with if calls like open() were used outside of assignment expressions.

•   The warning for arguments-differ now signals explicitly the difference it detected by naming the argument or arguments that changed and the type of change that occurred.

•   Suppress consider-using-with inside context managers.

    Closes #4430

•   Added --fail-on option to return non-zero exit codes regardless of --fail-under value.

•   numversion tuple contains integers again to fix multiple pylint's plugins that relied on it

    Closes #4420

•   Fix false-positive too-many-ancestors when inheriting from builtin classes, especially from the collections.abc module

    Closes #4166 Closes #4415

•   Stdlib deprecated modules check is moved to stdlib checker. New deprecated modules are added.

•   Fix raising false-positive no-member on abstract properties

•   Created new error message called arguments-renamed which identifies any changes at the parameter names of overridden functions.

    Closes #3536

•   New checker consider-using-dict-items. Emitted when iterating over dictionary keys and then indexing the same dictionary with the key within loop body.

    Closes #3389

•   Don't emit import-error if import guarded behind if sys.version_info >= (x, x)

•   Fix incompatibility with Python 3.6.0 caused by typing.Counter and typing.NoReturn usage

    Closes #4412

•   New checker use-maxsplit-arg. Emitted either when accessing only the first or last element of str.split().

    Closes #4440

•   Add ignore_signatures to duplicate code checker

    Closes #3619

•   Fix documentation errors in "Block disables" paragraph of User Guide.

•   New checker unnecessary-dict-index-lookup. Emitted when iterating over dictionary items (key-value pairs) and accessing the value by index lookup.

    Closes #4470

•   New checker``consider-using-from-import``. Emitted when a submodule/member of a package is imported and aliased with the same name.

    Closes #2309

•   Allow comma-separated list in output-format and separate output files for each specified format.

    Closes #1798

•   Make using-constant-test detect constant tests consisting of list literals like [] and [1, 2, 3].

•   Improved error message of unnecessary-comprehension checker by providing code suggestion.

    Closes #4499

•   New checker unused-private-member. Emitted when a private member (i.e., starts with __) of a class is defined but not used.

    Closes #4483

•   Fix false negative of consider-using-enumerate when iterating over an attribute.

    Closes #3657

•   New checker invalid-class-object. Emitted when a non-class is assigned to a __class__ attribute.

    Closes #585

•   Fix a crash when a plugin from the configuration could not be loaded and raise an error 'bad-plugin-value' instead

    Closes #4555

•   Added handling of floating point values when parsing configuration from pyproject.toml

    Closes #4518

•   invalid-length-returned, now also works when nothing at all is returned following an upgrade in astroid.

•   logging-format-interpolation and logging-not-lazy, now works on logger class created from renamed logging import following an upgrade in astroid.

•   Fix false-positive no-member with generic base class

    Closes PyCQA/astroid#942

•   Fix assigning-non-slot false-positive with base that inherits from typing.Generic

    Closes #4509 Closes PyCQA/astroid#999

•   New checker invalid-all-format. Emitted when __all__ has an invalid format, i.e. isn't a tuple or list.

•   Fix false positive unused-variable and undefined-variable with Pattern Matching in Python 3.10

•   New checker await-outside-async. Emitted when await is used outside an async function.

•   Clarify documentation for typing extension.

    Closes #4545

•   Add new extension CodeStyleChecker. It includes checkers that can improve code consistency. As such they don't necessarily provide a performance benefit and are often times opinionated.

•   New checker consider-using-tuple. Emitted when an in-place defined list or set can be replaced by a tuple.

•   New checker consider-using-namedtuple-or-dataclass. Emitted when dictionary values can be replaced by namedtuples or dataclass instances.

•   Fix error that occurred when using slice as subscript for dict.

•   Reduce false-positives around inference of .value and .name properties on Enum subclasses, following an upgrade in astroid

    Closes #1932 Closes #2062

•   Fix issue with cached_property that caused invalid-overridden-method error when overriding a property.

    Closes #4023

•   Fix unused-import false positive for imported modules referenced in attribute lookups in type comments.

    Closes #4603

  What's New in Pylint 2.8.3?

Release date: 2021-05-31

•   Astroid has been pinned to 2.5.6 for the 2.8 branch see #4527.

  What's New in Pylint 2.8.2?

Release date: 2021-04-26

•   Keep __pkginfo__.numversion a tuple to avoid breaking pylint-django.

    Closes #4405

•   scm_setuptools has been added to the packaging.

•   Pylint's tags are now the standard form vX.Y.Z and not pylint-X.Y.Z anymore.

•   New warning message deprecated-class. This message is emitted if import or call deprecated class of the standard library (like collections.Iterable that will be removed in Python 3.10).

    Closes #4388

  What's New in Pylint 2.8.1?

Release date: 2021-04-25

•   Add numversion back (temporarily) in __pkginfo__ because it broke Pylama and revert the unnecessary pylint.version breaking change.

    Closes #4399

  What's New in Pylint 2.8.0?

Release date: 2021-04-24

•   New refactoring message consider-using-with. This message is emitted if resource-allocating functions or methods of the standard library (like open() or threading.Lock.acquire()) that can be used as a context manager are called without a with block.

    Closes #3413

•   Resolve false positives on unused variables in decorator functions

    Closes #4252

•   Add new extension ConfusingConsecutiveElifChecker. This optional checker emits a refactoring message (R5601 confusing-consecutive-elif) if if/elif statements with different indentation levels follow directly one after the other.

•   New option --output=<file> to output result to a file rather than printing to stdout.

    Closes #1070

•   Use a prescriptive message for unidiomatic-typecheck

    Closes #3891

•   Apply const-naming-style to module constants annotated with typing.Final

•   The packaging is now done via setuptools exclusively. doc, tests, man, elisp and Changelog are not packaged anymore - reducing the size of the package by 75%.

•   Debian packaging is now (officially) done in https://salsa.debian.org/python-team/packages/pylint.

•   The 'doc' extra-require has been removed.

•   __pkginfo__ now only contain __version__ (also accessible with pylint.__version__), other meta-information are still accessible with from importlib import metadata;metadata.metadata('pylint').

•   COPYING has been renamed to LICENSE for standardization.

•   Fix false-positive used-before-assignment in function returns.

    Closes #4301

•   Updated astroid to 2.5.3

    Closes #2822, #4206, #4284

•   Add consider-using-min-max-builtin check for if statement which could be replaced by Python builtin min or max

    Closes #3406

•   Don't auto-enable postponed evaluation of type annotations with Python 3.10

•   Update astroid to 2.5.4

•   Add new extension TypingChecker. This optional checker can detect the use of deprecated typing aliases and can suggest the use of the alternative union syntax where possible. (For example, 'typing.Dict' can be replaced by 'dict', and 'typing.Unions' by '|', etc.) Make sure to check the config options if you plan on using it!

•   Reactivates old counts in report mode.

    Closes #3819

•   During detection of inconsistent-return-statements consider that assert False is a return node.

    Closes #4019

•   Run will not fail if score exactly equals config.fail_under.

•   Functions that never returns may declare NoReturn as type hints, so that inconsistent-return-statements is not emitted.

    Closes #4122, #4188

•   Improved protected access checks to allow access inside class methods

    Closes #1159

•   Fix issue with PEP 585 syntax and the use of collections.abc.Set

•   Fix issue that caused class variables annotated with typing.ClassVar to be identified as class constants. Now, class variables annotated with typing.Final are identified as such.

    Closes #4277

•   Continuous integration with read the doc has been added.

    Closes #3850

•   Don't show DuplicateBasesError for attribute access

•   Fix crash when checking setup.cfg for pylint config when there are non-ascii characters in there

    Closes #4328

•   Allow code flanked in backticks to be skipped by spellchecker

    Closes #4319

•   Allow Python tool directives (for black, flake8, zimports, isort, mypy, bandit, pycharm) at beginning of comments to be skipped by spellchecker

    Closes #4320

•   Fix issue that caused emacs pylint to fail when used with tramp

•   Improve check for invalid PEP 585 syntax inside functions if postponed evaluation of type annotations is enabled

•   Improve check for invalid PEP 585 syntax as default function arguments

  What's New in Pylint 2.7.4?

Release date: 2021-03-30

•   Fix a problem with disabled msgid not being ignored

    Closes #4265

•   Fix issue with annotated class constants

    Closes #4264

  What's New in Pylint 2.7.3?

Release date: 2021-03-29

•   Introduce logic for checking deprecated attributes in DeprecationMixin.

•   Reduce usage of blacklist/whitelist terminology. Notably, extension-pkg-allow-list is an alternative to extension-pkg-whitelist and the message blacklisted-name is now emitted as disallowed-name. The previous names are accepted to maintain backward compatibility.

•   Move deprecated checker to DeprecatedMixin

    Closes #4086

•   Bump astroid version to 2.5.2

•   Fix false positive for method-hidden when using private attribute and method

    Closes #3936

•   use-symbolic-message-instead now also works on legacy messages like C0111 (missing-docstring).

•   Remove unwanted print to stdout from _emit_no_member

•   Introduce a command-line option to specify pyreverse output directory

    Closes #4159

•   Fix issue with Enums and class-attribute-naming-style=snake_case

    Closes #4149

•   Add allowed-redefined-builtins option for fine tuning redefined-builtin check.

    Close #3263

•   Fix issue when executing with python -m pylint

    Closes #4161

•   Exempt typing.TypedDict from too-few-public-methods check.

    Closes #4180

•   Fix false-positive no-member for typed annotations without default value.

    Closes #3167

•   Add --class-const-naming-style for Enum constants and class variables annotated with typing.ClassVar

    Closes #4181

•   Fix astroid.Inference error for undefined-variables with len()`

    Closes #4215

•   Fix column index on FIXME warning messages

    Closes #4218

•   Improve handling of assignment expressions, better edge case handling

    Closes #3763, #4238

•   Improve check if class is subscriptable PEP585

•   Fix documentation and filename handling of --import-graph

•   Fix false-positive for unused-import on class keyword arguments

    Closes #3202

•   Fix regression with plugins on PYTHONPATH if latter is cwd

    Closes #4252

  What's New in Pylint 2.7.2?

Release date: 2021-02-28

•   Fix False Positive on Enum.__members__.items(), Enum.__members__.values, and Enum.__members__.keys Closes #4123

•   Properly strip dangerous sys.path entries (not just the first one)

    Closes #3636

•   Workflow and packaging improvements

  What's New in Pylint 2.7.1?

Release date: 2021-02-23

•   Expose UnittestLinter in pylint.testutils

•   Don't check directories starting with '.' when using register_plugins

    Closes #4119

  What's New in Pylint 2.7.0?

Release date: 2021-02-21

•   Introduce DeprecationMixin for reusable deprecation checks.

    Closes #4049

•   Fix false positive for builtin-not-iterating when map receives iterable

    Closes #4078

•   Python 3.6+ is now required.

•   Fix false positive for builtin-not-iterating when zip receives iterable

•   Add nan-comparison check for NaN comparisons

•   Bug fix for empty-comment message line number.

    Closes #4009

•   Only emit bad-reversed-sequence on dictionaries if below py3.8

    Closes #3940

•   Handle class decorators applied to function.

    Closes #3882

•   Add check for empty comments

•   Fix minor documentation issue in contribute.rst

•   Enums are now required to be named in UPPER_CASE by invalid-name.

    Close #3834

•   Add missing checks for deprecated functions.

•   Postponed evaluation of annotations are now recognized by default if python version is above 3.10

    Closes #3992

•   Fix column metadata for anomalous backslash lints

•   Drop support for Python 3.5

•   Add support for pep585 with postponed evaluation

    Closes #3320

•   Check alternative union syntax - PEP 604

    Closes #4065

•   Fix multiple false positives with assignment expressions

    Closes #3347, #3953, #3865, #3275

•   Fix TypedDict inherit-non-class false-positive Python 3.9+

    Closes #1927

•   Fix issue with nested PEP 585 syntax

•   Fix issue with nested PEP 604 syntax

•   Fix a crash in undefined-variable caused by chained attributes in metaclass

    Close #3742

•   Fix false positive for not-async-context-manager when contextlib.asynccontextmanager is used

    Close #3862

•   Fix linter multiprocessing pool shutdown (triggered warnings when runned in parallels with other pytest plugins)

    Closes #3779

•   Fix a false-positive emission of no-self-use and unused-argument for methods of generic structural types (Protocol[T])

    Closes #3885

•   Fix bug that lead to duplicate messages when using --jobs 2 or more.

    Close #3584

•   Adds option check-protected-access-in-special-methods in the ClassChecker to activate/deactivate protected-access message emission for single underscore prefixed attribute in special methods.

    Close #3120

•   Fix vulnerable regular expressions in pyreverse

    Close #3811

•   inconsistent-return-statements message is now emitted if one of try/except statement is not returning explicitly while the other do.

    Closes #3468

•   Fix useless-super-delegation false positive when default keyword argument is a dictionnary.

    Close #3773

•   Fix a crash when a specified config file does not exist

•   Add support to ignored-argument-names in DocstringParameterChecker and adds useless-param-doc and useless-type-doc messages.

    Close #3800

•   Enforce docparams consistently when docstring is not present

    Close #2738

•   Fix duplicate-code false positive when lines only contain whitespace and non-alphanumeric characters (e.g. parentheses, bracket, comma, etc.)

•   Improve lint message for singleton-comparison with bools

•   Fix spell-checker crash on indented docstring lines that look like # comments

    Close #3786

•   Fix AttributeError in checkers/refactoring.py

•   Improve sphinx directives spelling filter

•   Fix a bug with postponed evaluation when using aliases for annotations.

    Close #3798

•   Fix minor documentation issues

•   Improve the performance of the line length check.

•   Removed incorrect deprecation of inspect.getfullargspec

•   Fix signature-differs false positive for functions with variadics

    Close #3737

•   Fix a crash in consider-using-enumerate when encountering range() without arguments

    Close #3735

•   len-as-conditions is now triggered only for classes that are inheriting directly from list, dict, or set and not implementing the __bool__ function, or from generators like range or list/dict/set comprehension. This should reduce the false positives for other classes, like pandas's DataFrame or numpy's Array.

    Close #1879

•   Fixes duplicate-errors not working with -j2+

    Close #3314

•   generated-members now matches the qualified name of members

    Close #2498

•   Add check for bool function to len-as-condition

•   Add simplifiable-condition check for extraneous constants in conditionals using and/or.

•   Add condition-evals-to-constant check for conditionals using and/or that evaluate to a constant.

    Close #3407

•   Changed setup.py to work with distlib

    Close #3555

•   New check: consider-using-generator

    This check warns when a comprehension is used inside an any or all function, since it is unnecessary and should be replaced by a generator instead. Using a generator would be less code and way faster.

    Close #3165

•   Add Github Actions to replace Travis and AppVeyor in the future

  What's New in Pylint 2.6.1?

Release date: 2021-02-16

•   Astroid version has been set as < 2.5

    Close #4093

  What's New in Pylint 2.6.0?

Release date: 2020-08-20

•   Fix various scope-related bugs in undefined-variable checker

    Close #1082, #3434, #3461

•   bad-continuation and bad-whitespace have been removed, black or another formatter can help you with this better than Pylint

    Close #246, #289, #638, #747, #1148, #1179, #1943, #2041, #2301, #2304, #2944, #3565

•   The no-space-check option has been removed. It's no longer possible to consider empty line like a trailing-whitespace by using clever options

    Close #1368

•   missing-kwoa is no longer emitted when dealing with overload functions

    Close #3655

•   mixed-indentation has been removed, it is no longer useful since TabError is included directly in python3

    Close #2984 #3573

•   Add super-with-arguments check for flagging instances of Python 2 style super calls.

•   Add an faq detailing which messages to disable to avoid duplicates w/ other popular linters

•   Fix superfluous-parens false-positive for the walrus operator

    Close #3383

•   Fix fail-under not accepting floats

•   Fix a bug with ignore-docstrings ignoring all lines in a module

•   Fix pre-commit config that could lead to undetected duplicate lines of code

•   Fix a crash in parallel mode when the module's filepath is not set

    Close #3564

•   Add raise-missing-from check for exceptions that should have a cause.

•   Support both isort 4 and isort 5. If you have pinned isort 4 in your projet requirements, nothing changes. If you use isort 5, though, note that the known-standard-library option is not interpreted the same in isort 4 and isort 5 (see the migration guide in isort documentation for further details). For compatibility's sake for most pylint users, the known-standard-library option in pylint now maps to extra-standard-library in isort 5. If you really want what known-standard-library now means in isort 5, you must disable the wrong-import-order check in pylint and run isort manually with a proper isort configuration file.

    Close #3722

•   Fix a crash caused by not guarding against InferenceError when calling infer_call_result

    Close #3690

•   Fix a crash in parallel mode when the module's filepath is not set

    Close #3564

  What's New in Pylint 2.5.3?

Release date: 2020-06-8

•   Fix a regression where disable comments that have checker names with numbers in them are not parsed correctly

    Close #3666

•   property-with-parameters properly handles abstract properties

    Close #3600

•   continue-in-finally no longer emitted on Python 3.8 where it's now valid

    Close #3612

•   Fix a regression where messages with dash are not fully parsed

    Close #3604

•   In a TOML configuration file, it's now possible to use rich (non-string) types, such as list, integer or boolean instead of strings. For example, one can now define a list of message identifiers to enable like this:

    enable = [
        "use-symbolic-message-instead",
        "useless-suppression",
    ]

    Close #3538

•   Fix a regression where the score was not reported with multiple jobs

    Close #3547

•   Protect against AttributeError when checking cell-var-from-loop

    Close #3646

  What's New in Pylint 2.5.2?

Release date: 2020-05-05

•   pylint.Run accepts do_exit as a deprecated parameter

    Close #3590

  What's New in Pylint 2.5.1?

Release date: 2020-05-05

•   Fix a crash in method-hidden lookup for unknown base classes

    Close #3527

•   Revert pylint.Run's exit parameter to do_exit

    This has been inadvertently changed several releases ago to do_exit.

    Close #3533

•   no-value-for-parameter variadic detection has improved for assign statements

    Close #3563

•   Allow package files to be properly discovered with multiple jobs

    Close #3524

•   Allow linting directories without __init__.py which was a regression in 2.5.

    Close #3528

  What's New in Pylint 2.5.0?

Release date: 2020-04-27

•   Fix a false negative for undefined-variable when using class attribute in comprehension.

    Close #3494

•   Fix a false positive for undefined-variable when using class attribute in decorator or as type hint.

    Close #511 Close #1976

•   Remove HTML quoting of messages in JSON output.

    Close #2769

•   Adjust the invalid-name rule to work with non-ASCII identifiers and add the non-ascii-name rule.

    Close #2725

•   Positional-only arguments are taken in account for useless-super-delegation

•   unidiomatic-typecheck is no longer emitted for in and not in operators

    Close #3337

•   Positional-only argument annotations are taken in account for unused-import

    Close #3462

•   Add a command to list available extensions.

•   Allow used variables to be properly consumed when different checks are enabled / disabled

    Close #3445

•   Fix dangerous-default-value rule to account for keyword argument defaults

    Close #3373

•   Fix a false positive of self-assigning-variable on tuple unpacking.

    Close #3433

•   no-self-use is no longer emitted for typing stubs.

    Close #3439

•   Fix a false positive for undefined-variable when __class__ is used

    Close #3090

•   Emit invalid-name for variables defined in loops at module level.

    Close #2695

•   Add a check for cases where the second argument to isinstance is not a type.

    Close #3308

•   Add 'notes-rgx' option, to be used for fixme check.

    Close #2874

•   function-redefined exempts function redefined on a condition.

    Close #2410

•   typing.overload functions are exempted from docstring checks

    Close #3350

•   Emit invalid-overridden-method for improper async def overrides.

    Close #3355

•   Do not allow python -m pylint ... to import user code

    python -m pylint ... adds the current working directory as the first element of sys.path. This opens up a potential security hole where pylint will import user level code as long as that code resides in modules having the same name as stdlib or pylint's own modules.

    Close #3386

•   Add dummy-variables-rgx option for _redeclared-assigned-name check.

    Close #3341

•   Fixed graph creation for relative paths

•   Add a check for asserts on string literals.

    Close #3284

•   not in is considered iterating context for some of the Python 3 porting checkers.

•   A new check inconsistent-quotes was added.

•   Add a check for non string assignment to __name__ attribute.

    Close #583

•   __pow__, __imatmul__, __trunc__, __floor__, and __ceil__ are recognized as special method names.

    Close #3281

•   Added errors for protocol functions when invalid return types are detected. E0304 (invalid-bool-returned): __bool__ did not return a bool E0305 (invalid-index-returned): __index__ did not return an integer E0306 (invalid-repr-returned): __repr__ did not return a string E0307 (invalid-str-returned): __str__ did not return a string E0308 (invalid-bytes-returned): __bytes__ did not return a string E0309 (invalid-hash-returned): __hash__ did not return an integer E0310 (invalid-length-hint-returned): __length_hint__ did not return a non-negative integer E0311 (invalid-format-returned): __format__ did not return a string E0312 (invalid-getnewargs-returned): __getnewargs__ did not return a tuple E0313 (invalid-getnewargs-ex-returned): __getnewargs_ex__ did not return a tuple of the form (tuple, dict)

    Close #560

•   missing-*-docstring can look for __doc__ assignments.

    Close #3301

•   undefined-variable can now find undefined loop iterables

    Close #498

•   safe_infer can infer a value as long as all the paths share the same type.

    Close #2503

•   Add a --fail-under <score> flag, also configurable in a .pylintrc file. If the final score is more than the specified score, it's considered a success and pylint exits with exitcode 0. Otherwise, it's considered a failure and pylint exits with its current exitcode based on the messages issued.

    Close #2242

•   Don't emit line-too-long for multilines when disable=line-too-long comment stands at their end

    Close #2957

•   Fixed an AttributeError caused by improper handling of dataclasses inference in pyreverse

    Close #3256

•   Do not exempt bare except from undefined-variable and similar checks

    If a node was wrapped in a TryExcept, pylint was taking a hint from the except handler when deciding to emit or not a message. We were treating bare except as a fully fledged ignore but only the corresponding exceptions should be handled that way (e.g. NameError or ImportError)

    Close #3235

•   No longer emit assignment-from-no-return when a function only raises an exception

    Close #3218

•   Allow import aliases to exempt import-error when used in type annotations.

    Close #3178

•   Ellipsis` is exempted from ``multiple-statements for function overloads.

    Close #3224

•   No longer emit invalid-name for non-constants found at module level.

    Pylint was taking the following statement from PEP-8 too far, considering all module level variables as constants, which is not what the statement is saying:

    Constants are usually defined on a module level and written in all capital letters with underscores separating words.

    Close #3111 Close #3132

•   Allow implicit-str-concat-in-sequence to be emitted for string juxtaposition

    Close #3030

•   implicit-str-concat-in-sequence was renamed implicit-str-concat

•   The json reporter no longer bypasses redirect_stdout. Close #3227

•   Move NoFileError, OutputLine, FunctionalTestReporter, FunctionalTestFile, LintModuleTest and related methods from test_functional.py to pylint.testutils to help testing for 3rd party pylint plugins.

•   Can read config from a setup.cfg or pyproject.toml file.

    Close #617

•   Fix exception-escape false positive with generators

    Close #3128

•   inspect.getargvalues is no longer marked as deprecated.

•   A new check f-string-without-interpolation was added

    Close #3190

•   Flag mutable collections.* utilities as dangerous defaults

    Close #3183

•   docparams extension supports multiple types in raises sections.

    Multiple types can also be separated by commas in all valid sections.

    Closes #2729

•   Allow parallel linting when run under Prospector

•   Fixed false positives of method-hidden when a subclass defines the method that is being hidden.

    Closes #414

•   Python 3 porting mode is 30-50% faster on most codebases

•   Python 3 porting mode no longer swallows syntax errors

    Closes #2956

•   Pass the actual PyLinter object to sub processes to allow using custom PyLinter classes.

    PyLinter object (and all its members except reporter) needs to support pickling so the PyLinter object can be passed to worker processes.

•   Clean up setup.py

    Make pytest-runner a requirement only if running tests, similar to McCabe.

    Clean up the setup.py file, resolving a number of warnings around it.

•   Handle SyntaxError in files passed via --from-stdin option

    Pylint no longer outputs a traceback, if a file, read from stdin, contains a syntaxerror.

•   Fix uppercase style to disallow 3+ uppercase followed by lowercase.

•   Fixed undefined-variable and unused-import false positives when using a metaclass via an attribute.

    Close #1603

•   Emit unused-argument for functions that partially uses their argument list before raising an exception.

    Close #3246

•   Fixed broad_try_clause extension to check try/finally statements and to check for nested statements (e.g., inside of an if statement).

•   Recognize classes explicitly inheriting from abc.ABC or having an abc.ABCMeta metaclass as abstract. This makes them not trigger W0223.

    Closes #3098

•   Fix overzealous arguments-differ when overridden function uses variadics

    No message is emitted if the overriding function provides positional or keyword variadics in its signature that can feasibly accept and pass on all parameters given by the overridden function.

    Close #1482 Close #1553

•   Multiple types of string formatting are allowed in logging functions.

    The logging-fstring-interpolation message has been brought back to allow multiple types of string formatting to be used.

    Close #3361

  What's New in Pylint 2.4.4?

Release date: 2019-11-13

•   Exempt all the names found in type annotations from unused-import

    The previous code was assuming that only typing names need to be exempted, but we need to do that for the rest of the type comment names as well.

    Close #3112

•   Relax type import detection for names that do not come from the typing module

    Close #3191

  What's New in Pylint 2.4.3?

Release date: 2019-10-18

•   Fix an issue with unnecessary-comprehension in comprehensions with additional repacking of elements.

    Close #3148

•   import-outside-toplevel is emitted for ImportFrom nodes as well.

    Close #3175

•   Do not emit no-method-argument for functions using positional only args.

    Close #3161

•   consider-using-sys-exit is no longer emitted when exit is imported in the local scope.

    Close #3147

•   invalid-overridden-method takes abc.abstractproperty in account

    Close #3150

•   Fixed missing-yield-type-doc getting incorrectly raised when a generator does not document a yield type but has a type annotation.

    Closes #3185

•   typing.overload functions are exempted from too-many-function-args

    Close #3170

  What's New in Pylint 2.4.2?

Release date: 2019-09-30

•   ignored-modules can skip submodules. Close #3135

•   self-assigning-variable skips class level assignments. Close #2930

•   consider-using-sys-exit is exempted when exit() is imported from sys Close #3145

•   Exempt annotated assignments without variable from class-variable-slots-conflict

    Close #3141

•   Fix utils.is_error to account for functions returning early.

    This fixes a false negative with unused-variable which was no longer triggered when a function raised an exception as the last instruction, but the body of the function still had unused variables.

    Close #3028

  What's New in Pylint 2.4.1?

Release date: 2019-09-25

•   Exempt type checking definitions defined in both clauses of a type checking guard

    Close #3127

•   Exempt type checking definitions inside the type check guard

    In a7f236528bb3758886b97285a56f3f9ce5b13a99 we added basic support for emitting used-before-assignment if a variable was only defined inside a type checking guard (using TYPE_CHECKING variable from typing) Unfortunately that missed the case of using those type checking imports inside the guard itself, which triggered spurious used-before-assignment errors.

    Close #3119

•   Require astroid >= 2.3 to avoid any compatibility issues.

  What's New in Pylint 2.4.0?

Release date: 2019-09-24

•   New check: import-outside-toplevel

    This check warns when modules are imported from places other than a module toplevel, e.g. inside a function or a class.

•   Handle inference ambiguity for invalid-format-index

    Close #2752

•   Removed Python 2 specific checks such as relative-import, invalid-encoded-data, missing-super-argument.

•   Support forward references for function-redefined check.

    Close #2540

•   Handle redefinitions in case of type checking imports.

    Close #2834

•   Added a new check, consider-using-sys-exit

    This check is emitted when we detect that a quit() or exit() is invoked instead of sys.exit(), which is the preferred way of exiting in program.

    Close #2925

•   useless-suppression check now ignores cyclic-import suppressions, which could lead to false postiives due to incomplete context at the time of the check.

    Close #3064

•   Added new checks, no-else-break and no-else-continue

    These checks highlight unnecessary else and elif blocks after break and continue statements.

    Close #2327

•   Don't emit protected-access when a single underscore prefixed attribute is used inside a special method

    Close #1802

•   Fix the "statement" values in the PyLinter's stats reports by module.

•   Added a new check, invalid-overridden-method

    This check is emitted when we detect that a method is overridden as a property or a property is overridden as a method. This can indicate a bug in the application code that will trigger a runtime error.

    Close #2670

•   Added a new check, arguments-out-of-order

    This check warns if you have arguments with names that match those in a function's signature but you are passing them in to the function in a different order.

    Close #2975

•   Added a new check, redeclared-assigned-name

    This check is emitted when pylint detects that a name was assigned one or multiple times in the same assignment, which indicate a potential bug. Close #2898

•   Ignore lambda calls with variadic arguments without a context.

    Inferring variadic positional arguments and keyword arguments will result into empty Tuples and Dicts, which can lead in some cases to false positives with regard to no-value-for-parameter. In order to avoid this, until we'll have support for call context propagation, we're ignoring such cases if detected. We already did that for function calls, but the previous fix was not taking in consideration lambdas

    Close #2918

•   Added a new check, self-assigning-variable

    This check is emitted when we detect that a variable is assigned to itself, which might indicate a potential bug in the code application. Close #2930

•   Added a new check, property-with-parameters.

    This check is emitted when we detect that a defined property also has parameters, which are useless. Close #3006

•   Excluded protocol classes from a couple of checks. Close #3002.

•   Add a check unnecessary-comprehension that detects unnecessary comprehensions.

    This check is emitted when pylint finds list-, set- or dict-comprehensions, that are unnecessary and can be rewritten with the list-, set- or dict-constructors.

    Close #2905

•   Excluded PEP 526 instance and class variables from no-member. Close #2945

•   Excluded attrs from too-few-public-methods check. Close #2988.

•   unused-import emitted for the right import names in function scopes.

    Close #2928

•   Dropped support for Python 3.4.

•   assignment-from-no-return not triggered for async methods.

    Close #2902

•   Don't emit attribute-defined-outside-init for variables defined in setters.

    Close #409

•   Syntax errors report the column number.

    Close #2914

•   Support fully qualified typing imports for type annotations.

    Close #2915

•   Exclude __dict__ from attribute-defined-outside-init

•   Fix pointer on spelling check when the error are more than one time in the same line.

    Close #2895

•   Fix crash happening when parent of called object cannot be determined

•   Allow of in GoogleDocstring.re_multiple_type

•   Added subprocess-run-check to handle subrocess.run without explicitly set check keyword.

    Close #2848

•   When we can't infer bare except handlers, skip try-except-raise

    Close #2853

•   Handle more unnecessary-lambda cases when dealing with additional kwargs in wrapped calls

    Close #2845

•   Better postponed evaluation of annotations handling

    Close #2847

•   Support postponed evaluation of annotations for variable annotations.

    Close #2838

•   epylint.py_run defaults to python in case the current executable is not a Python one.

    Close #2837

•   Ignore raw docstrings when running Similarities checker with ignore-docstrings=yes option

•   Fix crash when calling inherit_from_std_ex on a class which is its own ancestor

    Close #2680

•   Added a new check that warns the user if a function call is used inside a test but parentheses are missing.

    Close #2658

•   len-as-condition now only fires when a len(x) call is made without an explicit comparison

    The message and description accompanying this checker has been changed reflect this new behavior, by explicitly asking to either rely on the fact that empty sequence are false or to compare the length with a scalar.

    Close #2684

•   Add preferred-module checker that notify if an import has a replacement module that should be used.

    This check is emitted when pylint finds an imported module that has a preferred replacement listed in preferred-modules.

•   assigning-non-slot not emitted for classes with unknown base classes.

    Close #2807

•   old-division is not emitted for non-Const nodes.

    Close #2808

•   Added method arguments to the dot writer for pyreverse.

    Close #2139

•   Support for linting file from stdin.

    IDEs may benefit from the support for linting from an in-memory file.

    Close #1187

•   Added a new check class-variable-slots-conflict

    This check is emitted when pylint finds a class variable that conflicts with a slot name, which would raise a ValueError at runtime.

•   Added new check: dict-iter-missing-items (E1141)

    Close #2761

•   Fix issue with pylint name in output of python -m pylint --version

    Close #2764

•   Relicense logo material under the CC BY-SA 4.0 license.

•   Skip if expressions from f-strings for the check_elif checker

    Close #2816

•   C0412 (ungrouped-import) is now compatible with isort.

    Close #2806

•   Added new extension to detect too much code in a try clause

    Close #2877

•   signature-mutators option was added With this option, users can choose to ignore too-many-function-args, unexpected-keyword-arg, and no-value-for-parameter for functions decorated with decorators that change the signature of a decorated function.

    Close #259

•   Fixed a pragma comment on its own physical line being ignored when part of a logical line with the previous physical line.

    Close #199

•   Fixed false undefined-loop-variable for a function defined in the loop, that uses the variable defined in that loop.

    Close #202

•   Fixed unused-argument and function-redefined getting raised for functions decorated with typing.overload.

    Close #1581

•   Fixed a false positive with consider-using-dict-comprehension for constructions that can't be converted to a comprehension

    Close #2963

•   Added __post_init__ to defining-attr-methods in order to avoid attribute-defined-outside-init in dataclasses.

    Close #2581

•   Changed description of W0199 to use the term 2-item-tuple instead of 2-uple.

•   Allow a . as a prefix for Sphinx name resolution.

•   Checkers must now keep a 1 to 1 relationship between "msgid" (ie: C1234) and "symbol" (ie : human-readable-symbol)

•   In checkers, an old_names can now be used for multiple new messages and pylint is now a little faster

    Caused by #1164. It means if you do a partial old_names for a message definition an exception will tell you that you must rename the associated identification.

•   Allow the choice of f-strings as a valid way of formatting logging strings.

    Closes #2395

•   Added --list-msgs-enabled command to list all enabled and disabled messages given the current RC file and command line arguments.

  What's New in Pylint 2.3.0?

Release date: 2019-02-27

•   Protect against NonDeducibleTypeHierarchy when calling semi-private is_subtype

    astroid.helpers.is_subtype raises NonDeducibleTypeHierarchy when it cannot infer the base classes of the given types, but that makes sense in its context given that the method is mostly used to inform the inference process about the hierarchy of classes. Doesn't make that much sense for pylint itself, which is why we're handling the exception here, rather than in astroid

    Close PyCQA/astroid#644

•   Added a new command line option list-groups for listing all the check groups pylint knows about.

•   Allow BaseException for emitting broad-except, just like Exception.

    Close #2741

•   Fixed a crash that occurred for bad-str-strip-call when strip() received None

    Close #2743

•   Don't emit *-not-iterating checks for builtins consumed by itertools

    Close #2731

•   Fix a crash caused by iterating over Uninferable in a string formatting check.

    Close #2727

•   Fixed false positives for no-self-argument and unsubscriptable-object when using __class_getitem__ (new in Python 3.7)

    Close #2416

•   Support Ellipsis as a synonym for pass statements.

    Close #2718

•   fixme gets triggered only on comments.

    Close #2321

•   Fixed a false positive for unused-variable and nonlocal assignments

    Close #2671

•   Added load_configuration() hook for plugins

    New optional hook for plugins is added: load_configuration(). This hook is executed after configuration is loaded to prevent overwriting plugin specific configuration via user-based configuration.

    Close #2635

•   Fix missing-raises-doc false positive (W9006)

    Close #1502

•   Exempt starred unpacking from *-not-iterating Python 3 checks

    Close #2651

•   Make compare-to-zero less zealous by checking against equality and identity

    Close #2645

•   Add no-else-raise warning (R1720)

    Close #2558

•   Exempt yield from from *-not-iterating Python 3 checks.

    Close #2643

•   Fix incorrect generation of no-else-return warnings (R1705)

    Fixed issue where if statements with nested if statements were incorrectly being flagged as no-else-return in some cases and not being flagged as no-else-return in other cases. Added tests for verification and updated pylint source files to eliminate newly exposed warnings.

•   Fix false positive with not-async-context-manager caused by not understanding contextlib.asynccontextmanager

    Close #2440

•   Refactor bad-reversed-sequence to account for more objects that can define __reversed__

    One such object would be an enum class, for which __reversed__ yields each individual enum. As such, the check for bad-reversed-sequence needs to not differentiate between classes and instances when it comes for checking of __reversed__ presence.

    Close #2598

•   Added wrong-exception-operation

    Used when an operation is done against an exception, but the operation is not valid for the exception in question. Usually emitted when having binary operations between exceptions in except handlers.

    Close #2494

•   no-member is emitted for enums when they lack a member

    Previously we weren't doing this because we detected a __getattr__ implementation on the Enum class (and this check is skipped for classes with __getattr__), but that is fine for Enums, given that they are inferred in a customised way in astroid.

    Close #2565

•   Generalize chained-comparison

    Previous version incorrectly detects a < b < c and b < d and fails to detect a < b < c and c < d.

•   Avoid popping __main__ when using multiple jobs

    Close #2689

•   Add a new option 'check-str-concat-over-line-jumps' to check 'implicit-str-concat-in-sequence'

•   Fixes for the new style logging format linter.

    The number of arguments was not handled properly, leading to an always successful check.

•   Fix false positive not-callable for uninferable properties.

•   Fix false positive useless-else-on-loop if the break is deep in the else of an inner loop.

•   Minor improvements to the help text for a few options.

  What's New in Pylint 2.2.2?

Release date: 2018-11-28

•   Change the logging-format-style to use name identifier instead of their corresponding Python identifiers

    This is to prevent users having to think about escaping the default value for logging-format-style in the generated config file. Also our config parsing utilities don't quite support escaped values when it comes to choices detection, so this would have needed various hacks around that.

    Closes #2614

  What's New in Pylint 2.2.1?

Release date: 2018-11-27

•   Fix a crash caused by implicit-str-concat-in-sequence and multi-bytes characters.

    Closes #2610

  What's New in Pylint 2.2?

Release date: 2018-11-25

•   Consider range() objects for undefined-loop-variable leaking from iteration.

    Close #2533

•   deprecated-method can use the attribute name for identifying a deprecated method

    Previously we were using the fully qualified name, which we still do, but the fully qualified name for some unittest deprecated aliases leads to a generic deprecation function. Instead on relying on that, we now also rely on the attribute name, which should solve some false positives.

    Close #1653 Close #1946

•   Fix compatibility with changes to stdlib tokenizer.

•   pylint is less eager to consume the whole line for pragmas

    Close #2485

•   Obtain the correct number of CPUs for virtualized or containerized environments.

    Close #2519

•   Change unbalanced-tuple-unpacking back to a warning.

    It used to be a warning until a couple of years ago, after it was promoted to an error. But the check might be suggesting the wrong thing in some cases, for instance when checking against sys.argv which cannot be known at static analysis time. Given it might rely on potential unknown data, it's best to have it as a warning.

    Close #2522

•   Remove enumerate usage suggestion when defining __iter__ (C0200)

    Close #2477

•   Emit too-many-starred-assignment only when the number of Starred nodes is per assignment elements

    Close #2513

•   try-except-raise checker now handles multilevel inheritance hirerachy for exceptions correctly.

    Close #2484

•   Add a new check, simplifiable-if-expression for expressions like True if cond else False.

    Close #2487

•   too-few-public-methods is not reported for typing.NamedTuple

    Close #2459

•   `too-few-public-methods is not reported for dataclasses created with options.

    Close #2488

•   Remove wrong modules from 'bad-python3-import'.

    Close #2453

•   The json reporter prints an empty list when no messages are emitted

    Close #2446

•   Add a new check, duplicate-string-formatting-argument

    This new check is emitted whenever a duplicate string formatting argument is found.

    Close #497

•   assignment-from-no-return is not emitted for coroutines.

    Close #1715

•   Report format string type mismatches.

•   consider-using-ternary and simplified-boolean-expression no longer emit for sequence based checks

    Close #2473

•   Handle AstroidSyntaxError when trying to import a module.

    Close #2313

•   Allow __module__ to be redefined at a class level. Close #2451

•   pylint used to emit an unused-variable error if unused import was found in the function. Now instead of unused-variable, unused-import is emitted.

    Close #2421

•   Handle asyncio.coroutine when looking for not-an-iterable check.

    Close #996

•   The locally-enabled check is gone.

    Close #2442

•   Infer decorated methods when looking for method-hidden

    Close #2369

•   Pick the latest value from the inferred values when looking for raising-non-exception

    Close #2431

•   Extend the TYPE_CHECKING guard to TYPE_CHECKING name as well, not just the attribute

    Close #2411

•   Ignore import x.y.z as z cases for checker useless-import-alias.

    Close #2309

•   Fix false positive undefined-variable and used-before-assignment with nonlocal keyword usage.

    Close #2049

•   Stop protected-access exception for missing class attributes

•   Don't emit assignment-from-no-return for decorated function nodes

    Close #2385

•   unnecessary-pass is now also emitted when a function or class contains only docstring and pass statement. In Python, stubbed functions often have a body that contains just a single pass statement, indicating that the function doesn't do anything. However, a stubbed function can also have just a docstring, and function with a docstring and no body also does nothing.

    Close #2208

•   duplicate-argument-name is emitted for more than one duplicate argument per function Close #1712

•   Allow double indentation levels for more distinguishable indentations

    Close #741

•   Consider tuples in exception handler for try-except-raise. Close #2389

•   Fix astroid.ClassDef check in checkers.utils.is_subclass_of

•   Fix wildcard imports being ignored by the import checker

•   Fix external/internal distinction being broken in the import graph

•   Fix wildcard import check not skipping __init__.py

    Close #2430

•   Add new option to logging checker, logging_format_style

•   Fix --ignore-imports to understand multi-line imports

    Close #1422 Close #2019

•   Add a new check 'implicit-str-concat-in-sequence' to spot string concatenation inside lists, sets & tuples.

•   literal-comparison is now emitted for 0 and 1 literals.

  What's New in Pylint 2.1.1?

Release date: 2018-08-07

•   fix pylint crash due to misplaced-format-function not correctly handling class attribute. Close #2384

•   Do not emit *-builtin for Python 3 builtin checks when the builtin is used inside a try-except

    Close PyCQA/pylint#2228

•   simplifiable-if-statement not emitted when dealing with subscripts

  What's New in Pylint 2.1?

Release date: 2018-08-01

•   trailing-comma-tuple gets emitted for yield statements as well. Close #2363

•   Get only the arguments of the scope function for redefined-argument-from-local

    Close #2364

•   Add a check misplaced-format-function which is emitted if format function is used on non str object.

    Close #2200

•   chain.from_iterable no longer emits dict-{}-not-iterating when dealing with dict values and keys

•   Demote the try-except-raise message from an error to a warning (E0705 -> W0706) Close #2323

•   Correctly handle the new name of the Python implementation of the abc module.

    Close PyCQA/astroid#2288

•   Modules with __getattr__ are exempted by default from no-member

    There's no easy way to figure out if a module has a particular member when the said module uses __getattr__, which is a new addition to Python 3.7. Instead we assume the safe thing to do, in the same way we do for classes, and skip those modules from checking.

    Close #2331

•   Fix a false positive invalid name message when method or attribute name is longer then 30 characters.

    Close #2047

•   Include the type of the next branch in no-else-return

    Close #2295

•   Fix inconsistent behaviour for bad-continuation on first line of file

    Close #2281

•   Fix not being able to disable certain messages on the last line through the global disable option

    Close #2278

•   Don't emit useless-return when we have a single statement that is the return itself

    We still want to be explicit when a function is supposed to return an optional value; even though pass could still work, it's not explicit enough and the function might look like it's missing an implementation. Close #2300

•   Fix false-positive undefined-variable for self referential class name in lamdbas Close #704

•   Don't crash when pylint is unable to infer the value of an argument to next()

    Close #2316

•   Don't emit not-an-iterable when dealing with async iterators.

    But do emit it when using the usual iteration protocol against async iterators.

    Close #2311

•   Can specify a default docstring type for when the check cannot guess the type Close #1169

  What's New in Pylint 2.0?

Release date: 2018-07-15

•   try-except-raise should not be emitted if there are any parent exception class handlers. Close #2284

•   trailing-comma-tuple can be emitted for return statements as well. Close #2269

•   Fix a false positive inconsistent-return-statements message when exception is raised inside an else statement.

    Close #1782

•   ImportFrom nodes correctly use the full name for the import sorting checks.

    Close #2181

•   [].extend and similar builtin operations don't emit dict-*-not-iterating with the Python 3 porting checker

    Close #2187

•   Add a check consider-using-dict-comprehension which is emitted if for dict initialization the old style with list comprehensions is used.

•   Add a check consider-using-set-comprehension which is emitted if for set initialization the old style with list comprehensions is used.

•   logging-not-lazy is emitted whenever pylint infers that a string is built with addition

    Close #2193

•   Add a check chained-comparison which is emitted if a boolean operation can be simplified by chaining some of its operations. e.g "a < b and b < c", can be simplified as "a < b < c".

    Close #2032

•   Add a check consider-using-in for comparisons of a variable against multiple values with "==" and "or"s instead of checking if the variable is contained "in" a tuple of those values.

•   in is considered iterating context for some of the Python 3 porting checkers

    Close #2186

•   Add --ignore-none flag to control if pylint should warn about no-member where the owner is None

•   Fix a false positive related to too-many-arguments and bounded __get__ methods

    Close #2172

•   mcs as the first parameter of metaclass's __new__ method was replaced by cls

    Close #2028

•   assignment-from-no-return considers methods as well. Close #2081

•   Support typing.TYPE_CHECKING for unused-import errors

    Close #1948

•   Inferred classes at a function level no longer emit invalid-name when they don't respect the variable regular expression

    Close #1049

•   Added basic support for postponed evaluation of function annotations.

    Close #2069

•   Fix a bug with missing-kwoa and variadics parameters

    Close #1111

•   simplifiable-if-statement takes in account only when assigning to same targets Close #1984

•   Make len-as-condition test more cases, such as len() < 1 or len <= 0

•   Fix false-positive line-too-long message emission for commented line at the end of a module

    Close #1950

•   Fix false-positive bad-continuation for with statements

    Close #461

•   Don't warn about stop-iteration-return when using next() over itertools.count

    Close #2158

•   Add a check consider-using-get for unidiomatic usage of value/default-retrieval for a key from a dictionary

    Close #2076

•   invalid-slice-index is not emitted when the slice is used as index for a complex object.

    We only use a handful of known objects (list, set and friends) to figure out if we should emit invalid-slice-index when the slice is used to subscript an object.

•   Don't emit unused-import anymore for typing imports used in type comments.

•   Add a new check 'useless-import-alias'.

    Close #2052

•   Add comparison-with-callable to warn for comparison with bare callable, without calling it.

    Close #2082

•   Don't warn for missing-type-doc and/or missing-return-type-doc, if type annotations exist on the function signature for a parameter and/or return type. Close #2083

•   Add --exit-zero option for continuous integration scripts to more easily call Pylint in environments that abort when a program returns a non-zero (error) status code.

    Close #2042

•   Warn if the first argument of an instance/ class method gets assigned

    Close #977

•   New check comparison-with-itself to check comparison between same value.

    Close #2051

•   Add a new warning, 'logging-fstring-interpolation', emitted when f-string is used within logging function calls.

    Close #1998

•   Don't show 'useless-super-delegation' if the subclass method has different type annotations.

    Close #1923

•   Add unhashable-dict-key check.

    Closes #586

•   Don't warn that a global variable is unused if it is defined by an import

    Close #1453

•   Skip wildcard import check for __init__.py.

    Close #2026

•   The Python 3 porting mode can now run with Python 3 as well.

•   too-few-public-methods is not emitted for dataclasses. Close #1793

•   New verbose mode option, enabled with --verbose command line flag, to display of extra non-checker-related output. It is disabled by default.

    Close #1863

•   undefined-loop-variable takes in consideration non-empty iterred objects before emitting

    Close #2039

•   Add support for numpydoc optional return value names.

    Close #2030

•   singleton-comparison accounts for negative checks

    Close #2037

•   Add a check consider-using-in for comparisons of a variable against multiple values with "==" and "or"s instead of checking if the variable is contained "in" a tuple of those values.

    Close #1977

•   defaultdict and subclasses of dict are now handled for dict-iter-* checks

    Close #2005

•   logging-format-interpolation also emits when f-strings are used instead of % syntax.

    Close #1788

•   Don't trigger misplaced-bare-raise when the raise is in a finally clause

    Close #1924

•   Add a new check, possibly-unused-variable.

    This is similar to unused-variable, the only difference is that it is emitted when we detect a locals() call in the scope of the unused variable. The locals() call could potentially use the said variable, by consuming all values that are present up to the point of the call. This new check allows to disable this error when the user intentionally uses locals() to consume everything.

    Close #1909.

•   no-else-return accounts for multiple cases The check was a bit overrestrictive because we were checking for return nodes in the .orelse node. At that point though the if statement can be refactored to not have the orelse. This improves the detection of other cases, for instance it now detects TryExcept nodes that are part of the .else branch.

    Close #1852

•   Added two new checks, invalid-envvar-value and invalid-envvar-default.

    The former is trigger whenever pylint detects that environment variable manipulation functions uses a different type than strings, while the latter is emitted whenever the said functions are using a default variable of different type than expected.

•   Add a check consider-using-join for concatenation of strings using str.join(sequence)

    Close #1952

•   Add a check consider-swap-variables for swapping variables with tuple unpacking

    Close #1922

•   Add new checker try-except-raise that warns the user if an except handler block has a raise statement as its first operator. The warning is shown when there is a bare raise statement, effectively re-raising the exception that was caught or the type of the exception being raised is the same as the one being handled.

•   Don't crash on invalid strings when checking for logging-format-interpolation

    Close #1944

•   Exempt __doc__ from triggering a redefined-builtin

    __doc__ can be used to specify a docstring for a module without passing it as a first-statement string.

•   Fix false positive bad-whitespace from function arguments with default values and annotations

    Close #1831

•   Fix stop-iteration-return false positive when next builtin has a default value in a generator

    Close #1830

•   Fix emission of false positive no-member message for class with "private" attributes whose name is mangled.

    Close #1643

•   Fixed a crash which occurred when Uninferable wasn't properly handled in stop-iteration-return

    Close #1779

•   Use the proper node to get the name for redefined functions (#1792)

    Close #1774

•   Don't crash when encountering bare raises while checking inconsistent returns

    Close #1773

•   Fix a false positive inconsistent-return-statements message when if statement is inside try/except.

    Close #1770

•   Fix a false positive inconsistent-return-statements message when while loop are used.

    Close #1772

•   Correct column number for whitespace conventions.

    Previously the column was stuck at 0

    Close #1649

•   Fix unused-argument false positives with overshadowed variable in dictionary comprehension.

    Close #1731

•   Fix false positive inconsistent-return-statements message when never returning functions are used (i.e sys.exit for example).

    Close #1771

•   Fix error when checking if function is exception, as in bad-exception-context.

•   Fix false positive inconsistent-return-statements message when a function is defined under an if statement.

    Close #1794

•   New useless-return message when function or method ends with a "return" or "return None" statement and this is the only return statement in the body.

•   Fix false positive inconsistent-return-statements message by avoiding useless exception inference if the exception is not handled.

    Close #1794 (second part)

•   Fix bad thread instantiation check when target function is provided in args.

    Close #1840

•   Fixed false positive when a numpy Attributes section follows a Parameters section

    Close #1867

•   Fix incorrect file path when file absolute path contains multiple path_strip_prefix strings.

    Close #1120

•   Fix false positive undefined-variable for lambda argument in class definitions

    Close #1824

•   Add of a new checker that warns the user if some messages are enabled or disabled by id instead of symbol.

    Close #1599

•   Suppress false-positive not-callable messages from certain staticmethod descriptors

    Close #1699

•   Fix indentation handling with tabs

    Close #1148

•   Fix false-positive bad-continuation error

    Close #638

•   Fix false positive unused-variable in lambda default arguments

    Close #1921 Close #1552 Close #1099 Close #210

•   Updated the default report format to include paths that can be clicked on in some terminals (e.g. iTerm).

•   Fix inline def behavior with too-many-statements checker

    Close #1978

•   Fix KeyError raised when using docparams and NotImplementedError is documented.

    Close #2102

•   Fix 'method-hidden' raised when assigning to a property or data descriptor.

•   Fix emitting useless-super-delegation when changing the default value of keyword arguments.

    Close #2022

•   Expand ignored-argument-names include starred arguments and keyword arguments

    Close #2214

•   Fix false-positive undefined-variable in nested lambda

    Close #760

•   Fix false-positive bad-whitespace message for typing annoatations with ellipses in them

    Close 1992

•   Broke down "missing-docstrings" between "module", "class" and "function"

    For this to work we had to make multiple messages with the same old name possible.

    Closes #1164

  What's New in Pylint 1.9?

Release date: 2018-05-15

•   Added two new Python 3 porting checks, exception-escape and comprehension-escape

    These two are emitted whenever pylint detects that a variable defined in the said blocks is used outside of the given block. On Python 3 these values are deleted.

•   Added a new deprecated-sys-function, emitted when accessing removed sys members.

•   Added xreadlines-attribute, emitted when the xreadlines() attribute is accessed.

•   The Python 3 porting mode can now run with Python 3 as well.

•   docparams extension allows abstract methods to document what overriding implementations should return, and to raise NotImplementedError without documenting it.

    Closes #2044

•   Special methods do not count towards too-few-methods, and are considered part of the public API.

•   Enum classes do not trigger too-few-methods

    Close #605

•   Added a new Python 2/3 check for accessing operator.div, which is removed in Python 3

    Close #1936

•   Added a new Python 2/3 check for accessing removed urllib functions

    Close #1997

  What's New in Pylint 1.8.1?

Release date: 2017-12-15

•   Wrong version number in __pkginfo__.

  What's New in Pylint 1.8?

Release date: 2017-12-15

•   Respect disable=... in config file when running with --py3k.

•   New warning shallow-copy-environ added

    Shallow copy of os.environ doesn't work as people may expect. os.environ is not a dict object but rather a proxy object, so any changes made on copy may have unexpected effects on os.environ

    Instead of copy.copy(os.environ) method os.environ.copy() should be used.

    See https://bugs.python.org/issue15373 for details.

    Close #1301

•   Do not display no-absolute-import warning multiple times per file.

•

trailing-comma-tuple refactor check now extends to assignment with
    more than one element (such as lists)

    Close #1713

•   Fixing u'' string in superfluous-parens message

    Close #1420

•   abstract-class-instantiated is now emitted for all inference paths. Close #1673

•   Add set of predefined naming style to ease configuration of checking naming conventions.

    Closes #1013

•   Added a new check, keyword-arg-before-vararg

    This is emitted for function definitions in which keyword arguments are placed before variable positional arguments (*args).

    This may lead to args list getting modified if keyword argument's value is not provided in the function call assuming it will take default value provided in the definition.

•   The invalid-name check contains the name of the template that caused the failure

    Close #1176

•   Using the -j flag won't start more child linters than needed.

    Contributed by Roman Ivanov in #1614

•   Fix a false positive with bad-python3-import on relative imports

    Close #1608

•   Added a new Python 3 check, non-ascii-bytes-literals

    Close #1545

•   Added a couple of new Python 3 checks for accessing dict methods in non-iterable context

•   Protocol checks (not-a-mapping, not-an-iterable and co.) aren't emitted on classes with dynamic getattr

•   Added a new warning, 'bad-thread-instantiation'

    This message is emitted when the threading.Thread class does not receive the target argument, but receives just one argument, which is by default the group parameter.

    Close #1327

•   In non-quiet mode, absolute path of used config file is logged to standard error. Close #1519

•   Raise meaningful exception for invalid reporter class being selected

    When unknown reporter class will be selected as Pylint reporter, meaningful error message would be raised instead of bare ImportError or AttribueError related to module or reporter class being not found. Close #1388

•   Added a new Python 3 check for accessing removed functions from itertools like izip or ifilterfalse

•   Added a new Python 3 check for accessing removed fields from the types module like UnicodeType or XRangeType

•   Added a new Python 3 check for declaring a method next that would have been treated as an iterator in Python 2 but a normal function in Python 3.

•   Added a new key-value pair in json output. The key is message-id and the value is the message id. Close #1512

•   Added a new Python 3.0 check for raising a StopIteration inside a generator. The check about raising a StopIteration inside a generator is also valid if the exception raised inherit from StopIteration. Close #1385

•   Added a new warning, raising-format-tuple, to detect multi-argument exception construction instead of message string formatting.

•   Added a new check for method of logging module that concatenate string via + operator Close #1479

•   Added parameter for limiting number of suggestions in spellchecking checkers

•   Fix a corner-case in consider-using-ternary checker.

    When object A used in X and A or B was falsy in boolean context, Pylint incorrectly emitted non-equivalent ternary-based suggestion. After a change message is correctly not emitted for this case. Close #1559

•   Added suggestion-mode configuration flag. When flag is enabled, informational message is emitted instead of cryptic error message for attributes accessed on c-extensions. Close #1466

•   Fix a false positive useless-super-delegation message when parameters default values are different from those used in the base class. Close #1085

•   Disabling 'wrong-import-order', 'wrong-import-position', or 'ungrouped-imports' for a single line now prevents that line from triggering violations on subsequent lines.

    Close #1336

•   Added a new Python check for inconsistent return statements inside method or function. Close #1267

•   Fix superfluous-parens false positive related to handling logical statements involving in operator.

    Close #574

•   function-redefined message is no longer emitted for functions and methods which names matches dummy variable name regular expression. Close #1369

•   Fix missing-param-doc and missing-type-doc false positives when mixing Args and Keyword Args in Google docstring. Close #1409

•   Fix missing-docstring false negatives when modules, classes, or methods consist of compound statements that exceed the docstring-min-length

•   Fix useless-else-on-loop false positives when break statements are deeply nested inside loop. Close #1661

•   Fix no wrong-import-order message emitted on ordering of first and third party libraries. With this fix, pylint distinguishes third and first party modules when checking import order. Close #1702

•   Fix pylint disable=fixme directives ignored for comments following the last statement in a file. Close #1681

•   Fix line-too-long message deactivated by wrong disable directive. The directive disable=fixme doesn't deactivate anymore the emission of line-too-long message for long commented lines. Close #1741

•   If the rcfile specified on the command line doesn't exist, then an IOError exception is raised. Close #1747

•   Fix the wrong scope of the disable= directive after a commented line. For example when a disable=line-too-long directive is at the end of a long commented line, it no longer disables the emission of line-too-long message for lines that follow. Close #1742

  What's New in Pylint 1.7.1?

Release date: 2017-04-17

•   Fix a false positive which occurred when an exception was reraised

    Close #1419

•   Fix a false positive of disallow-trailing-tuple

    The check was improved by verifying for non-terminating newlines, which should exempt function calls and function definitions from the check Close #1424

  What's New in Pylint 1.7?

Release date: 2017-04-13

•   Don't emit missing-final-newline or trailing-whitespace for formfeeds (page breaks).

    Close #1218 and #1219

•   Don't emit by default no-member if we have opaque inference objects in the inference results

    This is controlled through the new flag ignore-on-opaque-inference, which is by default True. The inference can return multiple potential results while evaluating a Python object, but some branches might not be evaluated, which results in partial inference. In that case, it might be useful to still emit no-member and other checks for the rest of the inferred objects.

•   Added new message assign-to-new-keyword to warn about assigning to names which will become a keyword in future Python releases.

    Close #1351

•   Split the 'missing or differing' in parameter documentation in different error. 'differing-param-doc' covers the differing part of the old 'missing-param-doc', and 'differing-type-doc' covers the differing part of the old 'missing-type-doc'

    Close #1342

•   Added a new error, 'used-prior-global-declaration', which is emitted when a name is used prior a global declaration in a function. This causes a SyntaxError in Python 3.6

    Close #1257

•   The protocol checks are emitting their messages when a special method is set to None.

    Close #1263

•   Properly detect if imported name is assigned to same name in different scope.

    Close #636, #848, #851, and #900

•   Require one space for annotations with type hints, as per PEP 8.

•   'trailing-comma-tuple' check was added

    This message is emitted when pylint finds an one-element tuple, created by a stray comma. This can suggest a potential problem in the code and it is recommended to use parantheses in order to emphasise the creation of a tuple, rather than relying on the comma itself.

•   Don't emit not-callable for instances with unknown bases.

    Close #1213

•   Treat keyword only arguments the same as positional arguments with regard to unused-argument check

•   Don't try to access variables defined in a separate scope when checking for protected-access

•   Added new check to detect incorrect usage of len(SEQUENCE) inside test conditions.

•   Added new extension to detect comparisons against empty string constants

•   Added new extension to detect comparisons of integers against zero

•   Added new error conditions for 'bad-super-call'

    Now detects super(type(self), self) and super(self.__class__, self) which can lead to recursion loop in derived classes.

•   PyLinter.should_analyze_file has a new optional parameter, called is_argument

    Close #1079

•   Add attribute hints for missing members

    Closes #1035

•   Add a new warning, 'redefined-argument-from-local'

    Closes #649

•   Support inline comments for comma separated values in the config file

    Closes #1024

•   epylint.py_run's script parameter was removed.

•   epylint.py_run now uses shell=False for running the underlying process.

    Closes #441

•   Added a new warning, 'useless-super-delegation'

    Close 839.

•   Added a new error, 'invalid-metaclass', raised when we can detect that a class is using an improper metaclass.

    Close #579

•   Added a new refactoring message, 'literal-comparison'.

    Close #786

•   arguments-differ takes in consideration kwonlyargs and variadics

    Close #983

•   Removed --optimized-ast. Part of #975.

•   Removed --files-output option. Part of #975.

•   Removed pylint-gui from the package.

•   Removed the HTML reporter. Part of #975.

•   ignored-argument-names is now used for ignoring arguments for unused-variable check.

    This option was used for ignoring arguments when computing the correct number of arguments a function should have, but for handling the arguments with regard to unused-variable check, dummy-variables-rgx was used instead. Now, ignored-argument-names is used for its original purpose and also for ignoring the matched arguments for the unused-variable check. This offers a better control of what should be ignored and how. Also, the same option was moved from the design checker to the variables checker, which means that the option now appears under the [VARIABLES] section inside the configuration file. Close #862.

•   Fix a false positive for keyword variadics with regard to keyword only arguments.

    If a keyword only argument was necessary for a function, but that function was called with keyword variadics (**kwargs), then we were emitting a missing-kwoa false positive, which is now fixed.

    Close #934.

•   Fix some false positives with unknown sized variadics.

    Close #878

•   Added a new extension, check_docstring, for checking PEP 257 conventions.

    Closes #868.

•   config files with BOM markers can now be read.

    Close #864.

•   epylint.py_run does not crash on big files, using .communicate() instead of .wait()

    Close #599

•   Disable reports by default and show the evaluation score by default

    As per discussion from issue #746, the reports were disabled by default in order to simplify the interaction between the tool and the users. The score is still shown by default, as a way of closely measuring when it increases or decreases due to changes brought to the code.

•   Disable the information category messages by default.

    This is a step towards making pylint more sane, as per the discussion from issue #746.

•   Catch more cases as not proper iterables for __slots__ with regard to invalid-slots pattern. Closes issue #775.

•   empty indent strings are rejected.

•   Added a new error, 'relative-beyond-top-level', which is emitted when a relative import was attempted beyond the top level package.

    Closes issue #588.

•   Added a new warning, 'unsupported-assignment-operation', which is emitted when item assignment is tried on an object which doesn't have this ability. Closes issue #591.

•   Added a new warning, 'unsupported-delete-operation', which is emitted when item deletion is tried on an object which doesn't have this ability. Closes issue #592.

•   Fix a false positive of 'redundant-returns-doc', occurred when the documented function was using yield instead of return.

    Closes issue #984.

•   Fix false positives of 'missing-[raises|params|type]-doc' due to not recognizing keyword synonyms supported by Sphinx.

•   Added a new refactoring message, 'consider-merging-isinstance', which is emitted whenever we can detect that consecutive isinstance calls can be merged together.

    Closes issue #968

•   Fix a false positive of 'missing-param-doc' and 'missing-type-doc', occurred when a class docstring uses the 'For the parameters, see' magic string but the class __init__ docstring does not, or vice versa.

•   redefined-outer-name is now also emitted when a nested loop's target variable is the same as a target variable in an outer loop.

    Closes issue #911.

•   Added proper exception type inference for 'missing-raises-doc'.

•   Added InvalidMessageError exception class to replace asserts in pylint.utils.

•   More thorough validation in MessagesStore.register_messages() to avoid one message accidentally overwriting another.

•   InvalidMessageError, UnknownMessage, and EmptyReport exceptions are moved to the new pylint.exceptions submodule.

•   UnknownMessage and EmptyReport are renamed to UnknownMessageError and EmptyReportError.

•   Warnings 'missing-returns-type-doc' and 'missing-yields-type-doc' have each been split into two warnings - 'missing-[return|yield]-doc' and 'missing-[return|yield]-type-doc'.

•   Added epytext support to docparams extension.

    Closes #1029.

•   Support having plugins with the same name and with options defined

    Closes #1018

•   Sort configuration options in a section

    Closes #1087

•   Added a new Python 3 warning around implementing '__div__', '__idiv__', or '__rdiv__' as those methods are phased out in Python 3.

•   Added a new warning, 'overlapping-except', which is emitted when two exceptions in the same except-clause are aliases for each other or one exceptions is an ancestor of another.

•   Avoid crashing on ill-formatted strings when checking for string formatting errors.

•   Added a new Python 3 warning for calling 'str.encode' or 'str.decode' with a non-text encoding.

•   Added new coding convention message, 'single-string-used-for-slots'.

    Closes #1166

•   Added a new Python 3 check for accessing 'sys.maxint' which was removed in Python 3 in favor of 'sys.maxsize'

•   Added a new Python 3 check for bad imports.

•   Added a new Python 3 check for accessing deprecated string functions.

•   Do not warn about unused arguments or function being redefined in singledispatch registered implementations.

    Closes #1032 and #1034

•   Added refactoring message 'no-else-return'.

•   Improve unused-variable checker to warn about unused variables in module scope.

    Closes #919

•   Ignore modules import as _ when checking for unused imports.

    Closes #1190

•   Improve handing of Python 3 classes with metaclasses declared in nested scopes.

    Closes #1177

•   Added refactoring message 'consider-using-ternary'.

    Closes #1204

•   Bug-fix for false-positive logging-format-interpolation` when format specifications are used in formatted string.

    Fixes #572

•   Added a new switch single-line-class-stmt to allow single-line declaration of empty class bodies.

    Closes #738

•   Protected access in form type(self)._attribute are now allowed.

    Fixes #1031

•   Let the user modify msg-template when Pylint is called from a Python script

    Fixes #1269

•   Imports checker supports new switch allow-wildcard-with-all which disables warning on wildcard import when imported module defines __all__ variable.

    Fixes #831

•   too-many-format-args and too-few-format-args are emitted correctly when starred expression are used in RHS tuple.

    Fixes #957

•   cyclic-import checker supports local disable clauses. When one of cycle imports was done in scope where disable clause was active, cycle is not reported as violation.

    Fixes #59

  What's new in Pylint 1.6.3?

Release date: 2016-07-18

•   Do not crash when inferring uninferable exception types for docparams extension

    Close #998

  What's new in Pylint 1.6.2?

Release date: 2016-07-15

•   Do not crash when printing the help of options with default regular expressions

    Close #990

•   More granular versions for deprecated modules.

    Close #991

  What's new in Pylint 1.6.1?

Release date: 2016-07-07

•   Use environment markers for supporting conditional dependencies.

  What's New in Pylint 1.6.0?

Release date: 2016-07-03

•   Added a new extension, pylint.extensions.mccabe, for warning about complexity in code.

•   Deprecate support for --optimize-ast. Part of #975.

•   Deprecate support for the HTML output. Part of #975.

•   Deprecate support for --output-files. Part of #975.

•   Fixed a documentation error for the check_docs extension. Fixes #735.

•   Made the list of property-defining decorators configurable.

•   Fix a bug where the top name of a qualified import was detected as unused variable.

    Close #923.

•   bad-builtin is now an extension check.

•   generated-members support qualified name through regular expressions.

    For instance, one can specify a regular expression as --generated-members=astroid.node_classes.* for ignoring every no-member error that is accessed as in astroid.node_classes.missing.object.

•   Add the ability to ignore files based on regex matching, with the new --ignore-patterns option.

    This addresses issue #156 by allowing for multiple ignore patterns to be specified. Rather than clobber the existing ignore option, we introduced a new one called ignore-patterns.

•   Added a new error, 'trailing-newlines', which is emitted when a file has trailing new lines.

    Closes issue #682.

•   Add a new option, 'redefining-builtins-modules', for controlling the modules which can redefine builtins, such as six.moves and future.builtins.

    Close #464.

•   'reimported' is emitted when the same name is imported from different module.

    Close #162.

•   Add a new recommendation checker, 'consider-iterating-dictionary', which is emitted which is emitted when a dictionary is iterated through .keys().

    Close #699

•   Use the configparser backport for Python 2

    This fixes a problem we were having with comments inside values, which is fixed in Python 3's configparser. Close #828

•   A new error was added, 'invalid-length-returned', when the __len__ special method returned something else than a non-negative number.

    Close issue #557

•   Switch to using isort internally for wrong-import-order.

    Closes #879.

•   check_docs extension can find constructor parameters in __init__.

    Closes #887.

•   Don't warn about invalid-sequence-index if the indexed object has unknown base classes.

    Closes #867

•   Don't crash when checking, for super-init-not-called, a method defined in an if block.

•   Do not emit import-error or no-name-in-module for fallback import blocks by default.

    Until now, we warned with these errors when a fallback import block (a TryExcept block that contained imports for Python 2 and 3) was found, but this gets cumbersome when trying to write compatible code. As such, we don't check these blocks by default, but the analysis can be enforced by using the new --analyse-fallback-block flag.

    Close #769.

  What's New in Pylint 1.5.5?

Release date: 2016-03-21

•   Let visit_importfrom from Python 3 porting checker be called when everything is disabled

    Because the visit method was filtering the patterns it was expecting to be activated, it didn't run when everything but one pattern was disabled, leading to spurious false positives

    Close #852

•   Don't emit unsubscriptable-value for classes with unknown base classes.

    Close #776.

•   Use an OrderedDict for storing the configuration elements

    This fixes an issue related to impredictible order of the disable / enable elements from a config file. In certain cases, the disable was coming before the enable which resulted in classes of errors to be enabled, even though the intention was to disable them. The best example for this was in the context of running multiple processes, each one of it having different enables / disables that affected the output.

    Close #815

•   Don't consider bare and broad except handlers as ignoring NameError, AttributeError and similar exceptions, in the context of checkers for these issues.

    Closes issue #826

  What's New in Pylint 1.5.4?

Release date: 2016-01-15

•   Merge StringMethodChecker with StringFormatChecker. This fixes a bug where disabling all the messages and enabling only a handful of messages from the StringFormatChecker would have resulted in no messages at all.

•   Don't apply unneeded-not over sets.

  What's New in Pylint 1.5.3?

Release date: 2016-01-11

•   Handle the import fallback idiom with regard to wrong-import-order.

    Closes issue #750.

•   Decouple the displaying of reports from the displaying of messages

    Some reporters are aggregating the messages instead of displaying them when they are available. The actual displaying was conflatted in the generate_reports. Unfortunately this behaviour was flaky and in the case of the JSON reporter, the messages weren't shown at all if a file had syntax errors or if it was missing. In order to fix this, the aggregated messages can now be displayed with Reporter.display_message, while the reports are displayed with display_reports.

    Closes issues #766 and #765.

•   Ignore function calls with variadic arguments without a context.

    Inferring variadic positional arguments and keyword arguments will result into empty Tuples and Dicts, which can lead in some cases to false positives with regard to no-value-for-parameter. In order to avoid this, until we'll have support for call context propagation, we're ignoring such cases if detected. Closes issue #722.

•   Treat AsyncFunctionDef just like FunctionDef nodes, by implementing visit_asyncfunctiondef in terms of visit_functiondef.

    Closes issue #767.

•   Take in account kwonlyargs when verifying that arguments are defined with the check_docs extension.

    Closes issue #745.

•   Suppress reporting 'unneeded-not' inside __ne__ methods

    Closes issue #749.

  What's New in Pylint 1.5.2?

Release date: 2015-12-21

•   Don't crash if graphviz is not installed, instead emit a warning letting the user to know.

    Closes issue #168.

•   Accept only functions and methods for the deprecated-method checker.

    This prevents a crash which can occur when an object doesn't have .qname() method after the inference.

•   Don't emit super-on-old-class on classes with unknown bases. Closes issue #721.

•   Allow statements in if or try blocks containing imports.

    Closes issue #714.

  What's New in Pylint 1.5.1?

Release date: 2015-12-02

•   Fix a crash which occurred when old visit methods are encountered in plugin modules. Closes issue #711.

•   Add wrong-import-position to check_messages's decorator arguments for ImportChecker.leave_module This fixes an esoteric bug which occurs when ungrouped-imports and wrong-import-order are disabled and pylint is executed on multiple files. What happens is that without wrong-import-position in check_messages, leave_module will never be called, which means that the first non-import node from other files might leak into the current file, leading to wrong-import-position being emitted by pylint.

•   Fix a crash which occurred when old visit methods are encountered in plugin modules. Closes issue #711.

•   Don't emit import-self and cyclic-import for relative imports of modules with the same name as the package itself. Closes issues #708 and #706.

  What's New in Pylint 1.5.0?

Release date: 2015-11-29

•   Added multiple warnings related to imports. 'wrong-import-order' is emitted when PEP 8 recommendations regarding imports are not respected (that is, standard imports should be followed by third-party imports and then by local imports). 'ungrouped-imports' is emitted when imports from the same package or module are not placed together, but scattered around in the code. 'wrong-import-position' is emitted when code is mixed with imports, being recommended for the latter to be at the top of the file, in order to figure out easier by a human reader what dependencies a module has. Closes issue #692.

•   Added a new refactoring warning, 'unneeded-not', emitted when an expression with the not operator could be simplified. Closes issue #670.

•   Added a new refactoring warning, 'simplifiable-if-statement', used when an if statement could be reduced to a boolean evaluation of its test. Closes issue #698.

•   Added a new refactoring warning, 'too-many-boolean-expressions', used when an if statement contains too many boolean expressions, which makes the code less maintainable and harder to understand. Closes issue #677.

•   Property methods are shown as attributes instead of functions in pyreverse class diagrams. Closes Issue #284

•   Add a new refactoring error, 'too-many-nested-blocks', which is emitted when a function or a method has too many nested blocks, which makes the code less readable and harder to understand. Closes issue #668.

•   Add a new error, 'unsubscriptable-object', that is emitted when value used in subscription expression doesn't support subscription (i.e. doesn't define __getitem__ method).

•   Don't warn about abstract classes instantiated in their own body. Closes issue #627.

•   Obsolete options are not present by default in the generated configuration file. Closes issue #632.

•   non-iterator-returned can detect classes with iterator-metaclasses. Closes issue #679.

•   Add a new error, 'unsupported-membership-test', emitted when value to the right of the 'in' operator doesn't support membership test protocol (i.e. doesn't define __contains__/__iter__/__getitem__)

•   Add new errors, 'not-an-iterable', emitted when non-iterable value is used in an iterating context (starargs, for-statement, comprehensions, etc), and 'not-a-mapping', emitted when non-mapping value is used in a mapping context. Closes issue #563.

•   Make 'no-self-use' checker not emit a warning if there is a 'super()' call inside the method. Closes issue #667.

•   Add checker to identify multiple imports on one line. Closes issue #598.

•   Fix unused-argument false positive when the "+=" operator is used. Closes issue #518.

•   Don't emit import-error for ignored modules. PyLint will not emit import errors for any import which is, or is a subpackage of, a module in the ignored-modules list. Closes issue #223.

•   Fix unused-import false positive when the import is used in a class assignment. Closes issue #475

•   Add a new error, 'not-context-manager', emitted when something that doesn't implement __enter__ and __exit__ is used in a with statement.

•   Add a new warning, 'confusing-with-statement', emitted by the base checker, when an ambiguous looking with statement is used. For example with open() as first, second which looks like a tuple assignment but is actually 2 context managers.

•   Add a new warning, 'duplicate-except', emitted when there is an exception handler which handles an exception type that was handled before. Closes issue #485.

•   A couple of warnings got promoted to errors, since they could uncover potential bugs in the code. These warnings are: assignment-from-none, unbalanced-tuple-unpacking, unpacking-non-sequence, non-iterator-returned. Closes issue #388.

•   Allow ending a pragma control with a semicolon. In this way, users can continue a pragma control with a reason for why it is used, as in # pylint: disable=old-style-class;reason=.... Closes issue #449.

•   --jobs can be used with --load-plugins now. Closes issue #456.

•   Improve the performance of --jobs when dealing only with a package name. Closes issue #479.

•   Don't emit an unused-wildcard-import when the imported name comes from another module and it is in fact a __future__ name.

•   The colorized reporter now works on Windows. Closes issue #96.

•   Remove pointless-except warning. It was previously disabled by default and it wasn't very useful. Closes issue #506.

•   Fix a crash on Python 3 related to the string checker, which crashed when it encountered a bytes string with a .format method called.

•   Don't warn about no-self-use for builtin properties.

•   Fix a false positive for bad-reversed-sequence, when a subclass of a dict provides a __reversed__ method.

•   Change the default no-docstring-rgx so missing-docstring isn't emitted for private functions.

•   Don't emit redefined-outer-name for __future__ directives. Closes issue #520.

•   Provide some hints for the bad-builtin message. Closes issue #522.

•   When checking for invalid arguments to a callable, in typecheck.py, look up for the __init__ in case the found __new__ comes from builtins.

    Since the __new__ comes from builtins, it will not have attached any information regarding what parameters it expects, so the check will be useless. Retrieving __init__ in that case will at least detect a couple of false negatives. Closes issue #429.

•   Don't emit no-member for classes with unknown bases.

    Since we don't know what those bases might add, we simply ignore the error in this case.

•   Lookup in the implicit metaclass when checking for no-member, if the class in question has an implicit metaclass, which is True for new style classes. Closes issue #438.

•   Add two new warnings, duplicate-bases and inconsistent-mro.

    duplicate-bases is emitted when a class has the same bases listed more than once in its bases definition, while inconsistent-mro is emitted when no sane mro hierarchy can be determined. Closes issue #526.

•   Remove interface-not-implemented warning. Closes issue #532.

•   Remove the rest of interface checks: interface-is-not-class, missing-interface-method, unresolved-interface. The reason is that its better to start recommending ABCs instead of the old Zope era of interfaces. One side effect of this change is that ignore-iface-methods becomes a noop, it's deprecated and it will be removed at some time.

•   Emit a proper deprecation warning for reporters.BaseReporter.add_message.

    The alternative way is to use handle_message. add_message will be removed in Pylint 1.6.

•   Added new module 'extensions' for optional checkers with the test directory 'test/extensions' and documentation file 'doc/extensions.rst'.

•   Added new checker 'extensions.check_docs' that verifies parameter documention in Sphinx, Google, and Numpy style.

•   Detect undefined variable cases, where the "definition" of an undefined variable was in del statement. Instead of emitting used-before-assignment, which is totally misleading, it now emits undefined-variable. Closes issue #528.

•   Don't emit attribute-defined-outside-init and access-member-before-definition for mixin classes. Actual errors can occur in mixin classes, but this is controlled by the ignore-mixin-members option. Closes issue #412.

•   Improve the detection of undefined variables and variables used before assignment for variables used as default arguments to function, where the variable was first defined in the class scope. Closes issue #342 and issue #404.

•   Add a new warning, 'unexpected-special-method-signature', which is emitted when a special method (dunder method) doesn't have the expected signature, which can lead to actual errors in the application code. Closes issue #253.

•   Remove 'bad-context-manager' due to the inclusion of 'unexpected-special-method-signature'.

•   Don't emit no-name-in-module if the import is guarded by an ImportError, Exception or a bare except clause.

•   Don't emit no-member if the attribute access node is protected by an except handler, which handles AttributeError, Exception or it is a bare except.

•   Don't emit import-error if the import is guarded by an ImportError, Exception or a bare except clause.

•   Don't emit undefined-variable if the node is guarded by a NameError, Exception or bare except clause.

•   Add a new warning, 'using-constant-test', which is emitted when a conditional statement (If, IfExp) uses a test which is always constant, such as numbers, classes, functions etc. This is most likely an error from the user's part. Closes issue #524.

•   Don't emit 'raising-non-exception' when the exception has unknown bases. We don't know what those bases actually are and it's better to assume that the user knows what he is doing rather than emitting a message which can be considered a false positive.

•   Look for a .pylintrc configuration file in the current folder, if pylintrc is not found. Dotted pylintrc files will not be searched in the parents of the current folder, as it is done for pylintrc.

•   Add a new error, 'invalid-unary-type-operand', emitted when an unary operand is used on something which doesn't support that operation (for instance, using the unary bitwise inversion operator on an instance which doesn't implement __invert__).

•   Take in consideration differences between arguments of various type of functions (classmethods, staticmethods, properties) when checking for arguments-differ. Closes issue #548.

•   astroid.inspector was moved to pylint.pyreverse, since it belongs there and it doesn't need to be in astroid.

•   astroid.utils.LocalsVisitor was moved to pylint.pyreverse.LocalsVisitor.

•   pylint.checkers.utils.excepts_import_error was removed. Use pylint.chekcers.utils.error_of_type instead.

•   Don't emit undefined-all-variables for nodes which can't be inferred (YES nodes).

•   yield-outside-func is also emitted for yield from.

•   Add a new error, 'too-many-star-expressions', emitted when there are more than one starred expression (*x) in an assignment. The warning is emitted only on Python 3.

•   Add a new error, 'invalid-star-assignment-target', emitted when a starred expression (*x) is used as the lhs side of an assignment, as in *x = [1, 2]. This is not a SyntaxError on Python 3 though.

•   Detect a couple of objects which can't be base classes (bool, slice, range and memoryview, which weren't detected until now).

•   Add a new error for the Python 3 porting checker, import-star-module-level, which is used when a star import is detected in another scope than the module level, which is an error on Python 3. Using this will emit a SyntaxWarning on Python 2.

•   Add a new error, 'star-needs-assignment-target', emitted on Python 3 when a Starred expression (*x) is not used in an assignment target. This is not caught when parsing the AST on Python 3, so it needs to be a separate check.

•   Add a new error, 'unsupported-binary-operation', emitted when two a binary arithmetic operation is executed between two objects which don't support it (a number plus a string for instance). This is currently disabled, since the it exhibits way too many false positives, but it will be reenabled as soon as possible.

•   New imported features from astroid into pyreverse: pyreverse.inspector.Project, pyreverse.inspector.project_from_files and pyreverse.inspector.interfaces.

    These were moved since they didn't belong in astroid.

•   Enable misplaced-future for Python 3. Closes issue #580.

•   Add a new error, 'nonlocal-and-global', which is emitted when a name is found to be both nonlocal and global in the same scope. Closes issue #581.

•   ignored-classes option can work with qualified names (ignored-classes=optparse.Values) Closes issue #297.

•   ignored-modules can work with qualified names as well as with Unix pattern matching for recursive ignoring. Closes issues #244.

•   Improve detection of relative imports in non-packages, as well as importing missing modules with a relative import from a package.

•   Don't emit no-init if not all the bases from a class are known. Closes issue #604.

•   --no-space-check option accepts empty-line as a possible option. Closes issue #541.

•   --generate-rcfile generates by default human readable symbols for the --disable option. Closes issue #608.

•   Improved the not-in-loop checker to properly detect more cases.

•   Add a new error, 'continue-in-finally', which is emitted when the continue keyword is found inside a finally clause, which is a SyntaxError.

•   The --zope flag is deprecated and it is slated for removal in Pylint 1.6.

    The reason behind this removal is the fact that it's a specialized flag and there are solutions for the original problem: use --generated-members with the members that causes problems when using Zope or add AST transforms tailored to the zope project.

    At the same time, --include-ids and --symbols will also be removed in Pylint 1.6. Closes issue #570.

•   missing-module-attribute was removed and the corresponding CLI option, required-attributes, which is slated for removal in Pylint 1.6.

•   missing-reversed-argument was removed.

    The reason behind this is that this kind of errors should be detected by the type checker for all the builtins and not as a special case for the reversed builtin. This will happen shortly in the future.

•   --comment flag is obsolete and it will be removed in Pylint 1.6.

•   --profile flag is obsolete and it will be removed in Pylint 1.6.

•   Add a new error, 'misplaced-bare-raise'.

    The error is used when a bare raise is not used inside an except clause. This can generate a RuntimeError in Python, if there are no active exceptions to be reraised. While it works in Python 2 due to the fact that the exception leaks outside of the except block, it's nevertheless a behaviour that a user shouldn't depend upon, since it's not obvious to the reader of the code what exception will be raised and it will not be compatible with Python 3 anyhow. Closes issue #633.

•   Bring logilab-common's ureports into pylint.reporters.

    With this change, we moved away from depending on logilab-common, having in Pylint all the components that were used from logilab-common. The API should be considered an implementation detail and can change at some point in the future. Closes issue #621.

•   reimported is emitted for reimported objects on the same line.

    Closes issue #639.

•   Abbreviations of command line options are not supported anymore.

    Using abbreviations for CLI options was never considered to be a feature of pylint, this fact being only a side effect of using optparse. As this was the case, using --load-plugin or other abbreviation for --load-plugins never actually worked, while it also didn't raise an error. Closes issue #424.

•   Add a new error, 'nonlocal-without-binding'

    The error is emitted on Python 3 when a nonlocal name is not bound to any variable in the parents scopes. Closes issue #582.

•

'deprecated-module' can be shown for modules which aren't
    available. Closes issue #362.

•   Don't consider a class abstract if its members can't be properly inferred.

    This fixes a false positive related to abstract-class-instantiated. Closes issue #648.

•   Add a new checker for the async features added by PEP 492.

•   Add a new error, 'yield-inside-async-function', emitted on Python 3.5 and upwards when the yield statement is found inside a new coroutine function (PEP 492).

•   Add a new error, 'not-async-context-manager', emitted when an async context manager block is used with an object which doesn't support this protocol (PEP 492).

•   Add a new convention warning, 'singleton-comparison', emitted when comparison to True, False or None is found.

•   Don't emit 'assigning-non-slot' for descriptors. Closes issue #652.

•   Add a new error, 'repeated-keyword', when a keyword argument is passed multiple times into a function call.

    This is similar with redundant-keyword-arg, but it's mildly different that it needs to be a separate error.

•   --enable=all can now be used. Closes issue #142.

•   Add a new convention message, 'misplaced-comparison-constant', emitted when a constant is placed in the left hand side of a comparison, as in '5 == func()'. This is also called Yoda condition, since the flow of code reminds of the Star Wars green character, conditions usually encountered in languages with variabile assignments in conditional statements.

•   Add a new convention message, 'consider-using-enumerate', which is emitted when code that uses range and len for iterating is encountered. Closes issue #684.

•   Added two new refactoring messages, 'no-classmethod-decorator' and 'no-staticmethod-decorator', which are emitted when a static method or a class method is declared without using decorators syntax.

    Closes issue #675.

  What's New in Pylint 1.4.3?

Release date: 2015-03-14

•   Remove three warnings: star-args, abstract-class-little-used, abstract-class-not-used. These warnings don't add any real value and they don't imply errors or problems in the code.

•   Added a new option for controlling the peephole optimizer in astroid. The option --optimize-ast will control the peephole optimizer, which is used to optimize a couple of AST subtrees. The current problem solved by the peephole optimizer is when multiple joined strings, with the addition operator, are encountered. If the numbers of such strings is high enough, Pylint will then fail with a maximum recursion depth exceeded error, due to its visitor architecture. The peephole just transforms such calls, if it can, into the final resulting string and this exhibit a problem, because the visit_binop method stops being called (in the optimized AST it will be a Const node).

  What's New in Pylint 1.4.2?

Release date: 2015-03-11

•   Don't require a docstring for empty modules. Closes issue #261.

•   Fix a false positive with too-few-format-args string warning, emitted when the string format contained a normal positional argument ('{0}'), mixed with a positional argument which did an attribute access ('{0.__class__}'). Closes issue #463.

•   Take in account all the methods from the ancestors when checking for too-few-public-methods. Closes issue #471.

•   Catch enchant errors and emit 'invalid-characters-in-docstring' when checking for spelling errors. Closes issue #469.

•   Use all the inferred statements for the super-init-not-called check. Closes issue #389.

•   Add a new warning, 'unichr-builtin', emitted by the Python 3 porting checker, when the unichr builtin is found. Closes issue #472.

•   Add a new warning, 'intern-builtin', emitted by the Python 3 porting checker, when the intern builtin is found. Closes issue #473.

•   Add support for editable installations.

•   The HTML output accepts the --msg-template option. Patch by Dan Goldsmith.

•   Add 'map-builtin-not-iterating' (replacing 'implicit-map-evaluation'), 'zip-builtin-not-iterating', 'range-builtin-not-iterating', and 'filter-builtin-not-iterating' which are emitted by --py3k when the appropriate built-in is not used in an iterating context (semantics taken from 2to3).

•   Add a new warning, 'unidiomatic-typecheck', emitted when an explicit typecheck uses type() instead of isinstance(). For example, type(x) == Y instead of isinstance(x, Y). Patch by Chris Rebert. Closes issue #299.

•   Add support for combining the Python 3 checker mode with the --jobs flag (--py3k and --jobs). Closes issue #467.

•   Add a new warning for the Python 3 porting checker, 'using-cmp-argument', emitted when the cmp argument for the list.sort or sorted builtin is encountered.

•   Make the --py3k flag commutative with the -E flag. Also, this patch fixes the leaks of error messages from the Python 3 checker when the errors mode was activated. Closes issue #437.

  What's New in Pylint 1.4.1?

Release date: 2015-01-16

•   Look only in the current function's scope for bad-super-call. Closes issue #403.

•   Check the return of properties when checking for not-callable. Closes issue #406.

•   Warn about using the input() or round() built-ins for Python 3. Closes issue #411.

•   Proper abstract method lookup while checking for abstract-class-instantiated. Closes issue #401.

•   Use a mro traversal for finding abstract methods. Closes issue #415.

•   Fix a false positive with catching-non-exception and tuples of exceptions.

•   Fix a false negative with raising-non-exception, when the raise used an uninferrable exception context.

•   Fix a false positive on Python 2 for raising-bad-type, when raising tuples in the form 'raise (ZeroDivisionError, None)'.

•   Fix a false positive with invalid-slots-objects, where the slot entry was a unicode string on Python 2. Closes issue #421.

•   Add a new warning, 'redundant-unittest-assert', emitted when using unittest's methods assertTrue and assertFalse with constant value as argument. Patch by Vlad Temian.

•   Add a new JSON reporter, usable through -f flag.

•   Add the method names for the 'signature-differs' and 'argument-differs' warnings. Closes issue #433.

•   Don't compile test files when installing.

•   Fix a crash which occurred when using multiple jobs and the files given as argument didn't exist at all.

  What's New in Pylint 1.4.0?

Release date: 2014-11-23

•   Added new options for controlling the loading of C extensions. By default, only C extensions from the stdlib will be loaded into the active Python interpreter for inspection, because they can run arbitrary code on import. The option --extension-pkg-whitelist can be used to specify modules or packages that are safe to load.

•   Change default max-line-length to 100 rather than 80

•   Drop BaseRawChecker class which were only there for backward compat for a while now

•   Don't try to analyze string formatting with objects coming from function arguments. Closes issue #373.

•   Port source code to be Python 2/3 compatible. This drops the need for 2to3, but does drop support for Python 2.5.

•   Each message now comes with a confidence level attached, and can be filtered base on this level. This allows to filter out all messages that were emitted even though an inference failure happened during checking.

•   Improved presenting unused-import message. Closes issue #293.

•   Add new checker for finding spelling errors. New messages: wrong-spelling-in-comment, wrong-spelling-in-docstring. New options: spelling-dict, spelling-ignore-words.

•   Add new '-j' option for running checks in sub-processes.

•   Added new checks for line endings if they are mixed (LF vs CRLF) or if they are not as expected. New messages: mixed-line-endings, unexpected-line-ending-format. New option: expected-line-ending-format.

•   'dangerous-default-value' no longer evaluates the value of the arguments, which could result in long error messages or sensitive data being leaked. Closes issue #282

•   Fix a false positive with string formatting checker, when encountering a string which uses only position-based arguments. Closes issue #285.

•   Fix a false positive with string formatting checker, when using keyword argument packing. Closes issue #288.

•   Proper handle class level scope for lambdas.

•   Handle 'too-few-format-args' or 'too-many-format-args' for format strings with both named and positional fields. Closes issue #286.

•   Analyze only strings by the string format checker. Closes issue #287.

•   Properly handle nested format string fields. Closes issue #294.

•   Don't emit 'attribute-defined-outside-init' if the attribute was set by a function call in a defining method. Closes issue #192.

•   Properly handle unicode format strings for Python 2. Closes issue #296.

•   Don't emit 'import-error' if an import was protected by a try-except, which excepted ImportError.

•   Fix an 'unused-import' false positive, when the error was emitted for all the members imported with 'from import' form. Closes issue #304.

•   Don't emit 'invalid-name' when assigning a name in an ImportError handler. Closes issue #302.

•   Don't count branches from nested functions.

•   Fix a false positive with 'too-few-format-args', when the format strings contains duplicate manual position arguments. Closes issue #310.

•   fixme regex handles comments without spaces after the hash. Closes issue #311.

•   Don't emit 'unused-import' when a special object is imported (__all__, __doc__ etc.). Closes issue #309.

•   Look in the metaclass, if defined, for members not found in the current class. Closes issue #306.

•   Don't emit 'protected-access' if the attribute is accessed using a property defined at the class level.

•   Detect calls of the parent's __init__, through a binded super() call.

•   Check that a class has an explicitly defined metaclass before emitting 'old-style-class' for Python 2.

•   Emit 'catching-non-exception' for non-class nodes. Closes issue #303.

•   Order of reporting is consistent.

•   Add a new warning, 'boolean-datetime', emitted when an instance of 'datetime.time' is used in a boolean context. Closes issue #239.

•   Fix a crash which occurred while checking for 'method-hidden', when the parent frame was something different than a function.

•   Generate html output for missing files. Closes issue #320.

•   Fix a false positive with 'too-many-format-args', when the format string contains mixed attribute access arguments and manual fields. Closes issue #322.

•   Extend the cases where 'undefined-variable' and 'used-before-assignment' can be detected. Closes issue #291.

•   Add support for customising callback identifiers, by adding a new '--callbacks' command line option. Closes issue #326.

•   Add a new warning, 'logging-format-interpolation', emitted when .format() string interpolation is used within logging function calls.

•   Don't emit 'unbalanced-tuple-unpacking' when the rhs of the assignment is a variable length argument. Closes issue #329.

•   Add a new warning, 'inherit-non-class', emitted when a class inherits from something which is not a class. Closes issue #331.

•   Fix another false positives with 'undefined-variable', where the variable can be found as a class assignment and used in a function annotation. Closes issue #342.

•   Handle assignment of the string format method to a variable. Closes issue #351.

•   Support wheel packaging format for PyPi. Closes issue #334.

•   Check that various built-ins that do not exist in Python 3 are not used: apply, basestring, buffer, cmp, coerce, execfile, file, long raw_input, reduce, StandardError, unicode, reload and xrange.

•   Warn for magic methods which are not used in any way in Python 3: __coerce__, __delslice__, __getslice__, __setslice__, __cmp__, __oct__, __nonzero__ and __hex__.

•   Don't emit 'assigning-non-slot' when the assignment is for a property. Closes issue #359.

•   Fix for regression: '{path}' was no longer accepted in '--msg-template'.

•   Report the percentage of all messages, not just for errors and warnings. Closes issue #319.

•   'too-many-public-methods' is reported only for methods defined in a class, not in its ancestors. Closes issue #248.

•   'too-many-lines' disable pragma can be located on any line, not only the first. Closes issue #321.

•   Warn in Python 2 when an import statement is found without a corresponding from __future__ import absolute_import.

•   Warn in Python 2 when a non-floor division operation is found without a corresponding from __future__ import division.

•   Add a new option, 'exclude-protected', for excluding members from the protected-access warning. Closes issue #48.

•   Warn in Python 2 when using dict.iter*(), dict.view*(); none of these methods are available in Python 3.

•   Warn in Python 2 when calling an object's next() method; Python 3 uses __next__() instead.

•   Warn when assigning to __metaclass__ at a class scope; in Python 3 a metaclass is specified as an argument to the 'class' statement.

•   Warn when performing parameter tuple unpacking; it is not supported in Python 3.

•   'abstract-class-instantiated' is also emitted for Python 2. It was previously disabled.

•   Add 'long-suffix' error, emitted when encountering the long suffix on numbers.

•   Add support for disabling a checker, by specifying an 'enabled' attribute on the checker class.

•   Add a new CLI option, --py3k, for enabling Python 3 porting mode. This mode will disable all other checkers and will emit warnings and errors for constructs which are invalid or removed in Python 3.

•   Add 'old-octal-literal' to Python 3 porting checker, emitted when encountering octals with the old syntax.

•   Add 'implicit-map-evaluation' to Python 3 porting checker, emitted when encountering the use of map builtin, without explicit evaluation.

  What's New in Pylint 1.3.0?

Release date: 2014-07-26

•   Allow hanging continued indentation for implicitly concatenated strings. Closes issue #232.

•   Pylint works under Python 2.5 again, and its test suite passes.

•   Fix some false positives for the cellvar-from-loop warnings. Closes issue #233.

•   Return new astroid class nodes when the inferencer can detect that that result of a function invocation on a type (like type or abc.ABCMeta) is requested. Closes #205.

•   Emit 'undefined-variable' for undefined names when using the Python 3 metaclass= argument.

•   Checkers respect priority now. Close issue #229.

•   Fix a false positive regarding W0511. Closes issue #149.

•   Fix unused-import false positive with Python 3 metaclasses (#143).

•   Don't warn with 'bad-format-character' when encountering the 'a' format on Python 3.

•   Add multiple checks for PEP 3101 advanced string formatting: 'bad-format-string', 'missing-format-argument-key', 'unused-format-string-argument', 'format-combined-specification', 'missing-format-attribute' and 'invalid-format-index'.

•   Issue broad-except and bare-except even if the number of except handlers is different than 1. Fixes issue #113.

•   Issue attribute-defined-outside-init for all cases, not just for the last assignment. Closes issue #262.

•   Emit 'not-callable' when calling properties. Closes issue #268.

•   Fix a false positive with unbalanced iterable unpacking, when encountering starred nodes. Closes issue #273.

•   Add new checks, 'invalid-slice-index' and 'invalid-sequence-index' for invalid sequence and slice indices.

•   Add 'assigning-non-slot' warning, which detects assignments to attributes not defined in slots.

•   Don't emit 'no-name-in-module' for ignored modules. Closes issue #223.

•   Fix an 'unused-variable' false positive, where the variable is assigned through an import. Closes issue #196.

•   Definition order is considered for classes, function arguments and annotations. Closes issue #257.

•   Don't emit 'unused-variable' when assigning to a nonlocal. Closes issue #275.

•   Do not let ImportError propagate from the import checker, leading to crash in some namespace package related cases. Closes issue #203.

•   Don't emit 'pointless-string-statement' for attribute docstrings. Closes issue #193.

•   Use the proper mode for pickle when opening and writing the stats file. Closes issue #148.

•   Don't emit hidden-method message when the attribute has been monkey-patched, you're on your own when you do that.

•   Only emit attribute-defined-outside-init for definition within the same module as the offended class, avoiding to mangle the output in some cases.

•   Don't emit 'unnecessary-lambda' if the body of the lambda call contains call chaining. Closes issue #243.

•   Don't emit 'missing-docstring' when the actual docstring uses .format. Closes issue #281.

  What's New in Pylint 1.2.1?

Release date: 2014-04-30

•   Restore the ability to specify the init-hook option via the configuration file, which was accidentally broken in 1.2.0.

•   Add a new warning [bad-continuation] for badly indentend continued lines.

•   Emit [assignment-from-none] when the function contains bare returns. Fixes BitBucket issue #191.

•   Added a new warning for closing over variables that are defined in loops. Fixes Bitbucket issue #176.

•   Do not warn about u escapes in string literals when Unicode literals are used for Python 2.*. Fixes BitBucket issue #151.

•   Extend the checking for unbalanced-tuple-unpacking and unpacking-non-sequence to instance attribute unpacking as well.

•   Fix explicit checking of python script (1.2 regression, #219)

•   Restore --init-hook, renamed accidentally into --init-hooks in 1.2.0 (#211)

•   Add 'indexing-exception' warning, which detects that indexing an exception occurs in Python 2 (behaviour removed in Python 3).

  What's New in Pylint 1.2.0?

Release date: 2014-04-18

•   Pass the current python paths to pylint process when invoked via epylint. Fixes BitBucket issue #133.

•   Add -i / --include-ids and -s / --symbols back as completely ignored options. Fixes BitBucket issue #180.

•   Extend the number of cases in which logging calls are detected. Fixes bitbucket issue #182.

•   Improve pragma handling to not detect pylint:* strings in non-comments. Fixes BitBucket issue #79.

•   Do not crash with UnknownMessage if an unknown message ID/name appears in disable or enable in the configuration. Patch by Cole Robinson. Fixes bitbucket issue #170.

•   Add new warning 'eval-used', checking that the builtin function eval was used.

•   Make it possible to show a naming hint for invalid name by setting include-naming-hint. Also make the naming hints configurable. Fixes BitBucket issue #138.

•   Added support for enforcing multiple, but consistent name styles for different name types inside a single module; based on a patch written by morbo@google.com.

•   Also warn about empty docstrings on overridden methods; contributed by sebastianu@google.com.

•   Also inspect arguments to constructor calls, and emit relevant warnings; contributed by sebastianu@google.com.

•   Added a new configuration option logging-modules to make the list of module names that can be checked for 'logging-not-lazy' et. al. configurable; contributed by morbo@google.com.

•   ensure init-hooks is evaluated before other options, notably load-plugins (#166)

•   Python 2.5 support restored: fixed small issues preventing pylint to run on python 2.5. Bitbucket issues #50 and #62.

•   bitbucket #128: pylint doesn't crash when looking for used-before-assignment in context manager assignments.

•   Add new warning, 'bad-reversed-sequence', for checking that the reversed() builtin receive a sequence (implements __getitem__ and __len__, without being a dict or a dict subclass) or an instance which implements __reversed__.

•   Mark file as a bad function when using python2 (closes #8).

•   Add new warning 'bad-exception-context', checking that raise ... from ... uses a proper exception context (None or an exception).

•   Enhance the check for 'used-before-assignment' to look for 'nonlocal' uses.

•   Emit 'undefined-all-variable' if a package's __all__ variable contains a missing submodule (closes #126).

•   Add a new warning 'abstract-class-instantiated' for checking that abstract classes created with abc module and with abstract methods are instantied.

•   Do not warn about 'return-arg-in-generator' in Python 3.3+.

•   Do not warn about 'abstract-method' when the abstract method is implemented through assignment (#155).

•   Improve cyclic import detection in the case of packages, patch by Buck Golemon

•   Add new warnings for checking proper class __slots__: invalid-slots-object and invalid-slots.

•   Search for rc file in ~/.config/pylintrc if ~/.pylintrc doesn't exists (#121)

•   Don't register the newstyle checker w/ python >= 3

•   Fix unused-import false positive w/ augment assignment (#78)

•   Fix access-member-before-definition false negative wrt aug assign (#164)

•   Do not attempt to analyze non python file, eg .so file (#122)

  What's New in Pylint 1.1.0?

Release date: 2013-12-22

•   Add new check for use of deprecated pragma directives "pylint:disable-msg" or "pylint:enable-msg" (I0022, deprecated-pragma) which was previously emitted as a regular warn().

•   Avoid false used-before-assignment for except handler defined identifier used on the same line (#111).

•   Combine 'no-space-after-operator', 'no-space-after-comma' and 'no-space-before-operator' into a new warning 'bad-whitespace'.

•   Add a new warning 'superfluous-parens' for unnecessary parentheses after certain keywords.

•   Fix a potential crash in the redefine-in-handler warning if the redefined name is a nested getattr node.

•   Add a new option for the multi-statement warning to allow single-line if statements.

•   Add 'bad-context-manager' error, checking that '__exit__' special method accepts the right number of arguments.

•   Run pylint as a python module 'python -m pylint' (anatoly techtonik).

•   Check for non-exception classes inside an except clause.

•   epylint support options to give to pylint after the file to analyze and have basic input validation (bitbucket #53 and #54), patches provided by felipeochoa and Brian Lane.

•   Added a new warning, 'non-iterator-returned', for non-iterators returned by '__iter__'.

•   Add new checks for unpacking non-sequences in assignments (unpacking-non-sequence) as well as unbalanced tuple unpacking (unbalanced-tuple-unpacking).

•   useless-else-on-loop not emitted if there is a break in the else clause of inner loop (#117).

•   don't mark input as a bad function when using python3 (#110).

•   badly-implemented-container caused several problems in its current implementation. Deactivate it until we have something better. See #112 for instance.

•   Use attribute regexp for properties in python3, as in python2

•   Create the PYLINTHOME directory when needed, it might fail and lead to spurious warnings on import of pylint.config.

•   Fix setup.py so that pylint properly install on Windows when using python3

•   Various documentation fixes and enhancements

•   Fix issue #55 (false-positive trailing-whitespace on Windows)

  What's New in Pylint 1.0.0?

Release date: 2013-08-06

•   Add check for the use of 'exec' function

•   New --msg-template option to control output, deprecating "msvc" and "parseable" output formats as well as killing --include-ids and --symbols options

•   Do not emit [fixme] for every line if the config value 'notes' is empty, but [fixme] is enabled.

•   Emit warnings about lines exceeding the column limit when those lines are inside multiline docstrings.

•   Do not double-check parameter names with the regex for parameters and inline variables.

•   Added a new warning missing-final-newline (C0304) for files missing the final newline.

•   Methods that are decorated as properties are now treated as attributes for the purposes of name checking.

•   Names of derived instance class member are not checked any more.

•   Names in global statements are now checked against the regular expression for constants.

•   For toplevel name assignment, the class name regex will be used if pylint can detect that value on the right-hand side is a class (like collections.namedtuple()).

•   Simplified invalid-name message

•   Added a new warning invalid-encoded-data (W0512) for files that contain data that cannot be decoded with the specified or default encoding.

•   New warning bad-open-mode (W1501) for calls to open (or file) that specify invalid open modes (Original implementation by Sasha Issayev).

•   New warning old-style-class (C1001) for classes that do not have any base class.

•   Add new name type 'class_attribute' for attributes defined in class scope. By default, allow both const and variable names.

•   New warning trailing-whitespace (C0303) that warns about trailing whitespace.

•   Added a new warning unpacking-in-except (W0712) about unpacking exceptions in handlers, which is unsupported in Python 3.

•   Add a configuration option for missing-docstring to optionally exempt short functions/methods/classes from the check.

•   Add the type of the offending node to missing-docstring and empty-docstring.

•   New utility classes for per-checker unittests in testutils.py

•   Do not warn about redefinitions of variables that match the dummy regex.

•   Do not treat all variables starting with _ as dummy variables, only _ itself.

•   Make the line-too-long warning configurable by adding a regex for lines for with the length limit should not be enforced

•   Do not warn about a long line if a pylint disable option brings it above the length limit

•   Do not flag names in nested with statements as undefined.

•   Added a new warning 'old-raise-syntax' for the deprecated syntax raise Exception, args

•   Support for PEP 3102 and new missing-kwoa (E1125) message for missing mandatory keyword argument (logilab.org's #107788)

•   Fix spelling of max-branchs option, now max-branches

•   Added a new base class and interface for checkers that work on the tokens rather than the syntax, and only tokenize the input file once.

•   Follow astng renaming to astroid

•   bitbucket #37: check for unbalanced unpacking in assignments

•   bitbucket #25: fix incomplete-protocol false positive for read-only containers like tuple

•   bitbucket #16: fix False positive E1003 on Python 3 for argument-less super()

•   bitbucket #6: put back documentation in source distribution

•   bitbucket #15: epylint shouldn't hang anymore when there is a large output on pylint'stderr

•   bitbucket #7: fix epylint w/ python3

•   bitbucket #3: remove string module from the default list of deprecated modules

  What's New in Pylint 0.28.0?

Release date: 2013-04-25

•   bitbucket #1: fix "dictionary changed size during iteration" crash

•   #74013: new E1310[bad-str-strip-call] message warning when a call to a {l,r,}strip method contains duplicate characters (patch by Torsten Marek)

•   #123233: new E0108[duplicate-argument-name] message reporting duplicate argument names

•   #81378: emit W0120[useless-else-on-loop] for loops without break

•   #124660: internal dependencies should not appear in external dependencies report

•   #124662: fix name error causing crash when symbols are included in output messages

•   #123285: apply pragmas for warnings attached to lines to physical source code lines

•   #123259: do not emit E0105 for yield expressions inside lambdas

•   #123892: don't crash when attempting to show source code line that can't be encoded with the current locale settings

•   Simplify checks for dangerous default values by unifying tests for all different mutable compound literals.

•   Improve the description for E1124[redundant-keyword-arg]

  What's New in Pylint 0.27.0?

Release date: 2013-02-26

•   #20693: replace pylint.el by Ian Eure version (patch by J.Kotta)

•   #105327: add support for --disable=all option and deprecate the 'disable-all' inline directive in favour of 'skip-file' (patch by A.Fayolle)

•   #110840: add messages I0020 and I0021 for reporting of suppressed messages and useless suppression pragmas. (patch by Torsten Marek)

•   #112728: add warning E0604 for non-string objects in __all__ (patch by Torsten Marek)

•   #120657: add warning W0110/deprecated-lambda when a map/filter of a lambda could be a comprehension (patch by Martin Pool)

•   #113231: logging checker now looks at instances of Logger classes in addition to the base logging module. (patch by Mike Bryant)

•   #111799: don't warn about octal escape sequence, but warn about o which is not octal in Python (patch by Martin Pool)

•   #110839: bind <F5> to Run button in pylint-gui

•   #115580: fix erroneous W0212 (access to protected member) on super call (patch by Martin Pool)

•   #110853: fix a crash when an __init__ method in a base class has been created by assignment rather than direct function definition (patch by Torsten Marek)

•   #110838: fix pylint-gui crash when include-ids is activated (patch by Omega Weapon)

•   #112667: fix emission of reimport warnings for mixed imports and extend the testcase (patch by Torsten Marek)

•   #112698: fix crash related to non-inferable __all__ attributes and invalid __all__ contents (patch by Torsten Marek)

•   Python 3 related fixes:

•

#110213: fix import of checkers broken with python 3.3, causing
    "No such message id W0704" breakage

•   #120635: redefine cmp function used in pylint.reporters

•   Include full warning id for I0020 and I0021 and make sure to flush warnings after each module, not at the end of the pylint run. (patch by Torsten Marek)

•   Changed the regular expression for inline options so that it must be preceded by a # (patch by Torsten Marek)

•   Make dot output for import graph predictable and not depend on ordering of strings in hashes. (patch by Torsten Marek)

•   Add hooks for import path setup and move pylint's sys.path modifications into them. (patch by Torsten Marek)

  What's New in Pylint 0.26.0?

Release date: 2012-10-05

•   #106534: add --ignore-imports option to code similarity checking and 'symilar' command line tool (patch by Ry4an Brase)

•   #104571: check for anomalous backslash escape, introducing new W1401 and W1402 messages (patch by Martin Pool)

•   #100707: check for boolop being used as exception class, introducing new W0711 message (patch by Tim Hatch)

•   #4014: improve checking of metaclass methods first args, introducing new C0204 message (patch by lothiraldan@gmail.com finalized by sthenault)

•   #4685: check for consistency of a module's __all__ variable, introducing new E0603 message

•   #105337: allow custom reporter in output-format (patch by Kevin Jing Qiu)

•   #104420: check for protocol completness and avoid false R0903 (patch by Peter Hammond)

•   #100654: fix grammatical error for W0332 message (using 'l' as long int identifier)

•   #103656: fix W0231 false positive for missing call to object.__init__ (patch by lothiraldan@gmail.com)

•   #63424: fix similarity report disabling by properly renaming it to RP0801

•   #103949: create a console_scripts entry point to be used by easy_install, buildout and pip

•   fix cross-interpreter issue (non compatible access to __builtins__)

•   stop including tests files in distribution, they causes crash when installed with python3 (#72022, #82417, #76910)

  What's New in Pylint 0.25.2?

Release date: 2012-07-17

•   #93591: Correctly emit warnings about clobbered variable names when an except handler contains a tuple of names instead of a single name. (patch by tmarek@google.com)

•   #7394: W0212 (access to protected member) not emitted on assigments (patch by lothiraldan@gmail.com)

•   #18772; no prototype consistency check for mangled methods (patch by lothiraldan@gmail.com)

•   #92911: emit W0102 when sets are used as default arguments in functions (patch by tmarek@google.com)

•   #77982: do not emit E0602 for loop variables of comprehensions used as argument values inside a decorator (patch by tmarek@google.com)

•   #89092: don't emit E0202 (attribute hiding a method) on @property methods

•   #92584: fix pylint-gui crash due to internal API change

•   #87192: fix crash when decorators are accessed through more than one dot (for instance @a.b is fine, @a.b.c crash)

•   #88914: fix parsing of --generated-members options, leading to crash when using a regexp value set

•   fix potential crashes with utils.safe_infer raising InferenceError

  What's New in Pylint 0.25.1?

Release date: 2011-12-08

•   #81078: Warn if names in exception handlers clobber overwrite existing names (patch by tmarek@google.com)

•   #81113: Fix W0702 messages appearing with the wrong line number. (patch by tmarek@google.com)

•   #50461, #52020, #51222: Do not issue warnings when using 2.6's property.setter/deleter functionality (patch by dneil@google.com)

•   #9188, #4024: Do not trigger W0631 if a loop variable is assigned in the else branch of a for loop.

  What's New in Pylint 0.25.0?

Release date: 2011-10-7

•   #74742: make allowed name for first argument of class method configurable (patch by Google)

•   #74087: handle case where inference of a module return YES; this avoid some cases of "TypeError: '_Yes' object does not support indexing" (patch by Google)

•   #74745: make "too general" exception names configurable (patch by Google)

•   #74747: crash occurs when lookup up a special attribute in class scope (patch by google)

•   #76920: crash if on eg "pylint --rcfile" (patch by Torsten Marek)

•   #77237: warning for E0202 may be very misleading

•   #73941: HTML report messages table is badly rendered

  What's New in Pylint 0.24.0?

Release date: 2011-07-18

•   #69738: add regular expressions support for "generated-members"

•   ids of logging and string_format checkers have been changed: logging: 65 -> 12, string_format: 99 -> 13 Also add documentation to say that ids of range 1-50 shall be reserved to pylint internal checkers

•   #69993: Additional string format checks for logging module: check for missing arguments, too many arguments, or invalid string formats in the logging checker module. Contributed by Daniel Arena

•   #69220: add column offset to the reports. If you've a custom reporter, this change may break it has now location gain a new item giving the column offset.

•   #60828: Fix false positive in reimport check

•   #70495: absolute imports fail depending on module path (patch by Jacek Konieczny)

•   #22273: Fix --ignore option documentation to match reality

  What's New in Pylint 0.23.0?

Release date: 2011-01-11

•   documentation update, add manpages

•   several performance improvements

•   finalize python3 support

•   new W0106 warning 'Expression "%s" is assigned to nothing'

•   drop E0501 and E0502 messages about wrong source encoding: not anymore interesting since it's a syntax error for python >= 2.5 and we now only support this python version and above.

•   don't emit W0221 or W0222 when methods as variable arguments (eg *arg and/or **args). Patch submitted by Charles Duffy.

  What's New in Pylint 0.22.0?

Release date: 2010-11-15

•   python versions: minimal python3.x support; drop python < 2.5 support

  What's New in Pylint 0.21.4?

Release date: 2010-10-27

•   fix #48066: pylint crashes when redirecting output containing non-ascii characters

•   fix #19799: "pylint -blah" exit with status 2

•   update documentation

  What's New in Pylint 0.21.3?

Release date: 2010-09-28

•   restored python 2.3 compatibility. Along with logilab-astng 0.21.3 and logilab-common 0.52, this will much probably be the latest release supporting python < 2.5.

  What's New in Pylint 0.21.2?

Release date: 2010-08-26

•   fix #36193: import checker raise exception on cyclic import

•   fix #28796: regression in --generated-members introduced pylint 0.20

•   some documentation cleanups

  What's New in Pylint 0.21.1?

Release date: 2010-06-04

•   fix #28962: pylint crash with new options, due to missing stats data while writing the Statistics by types report

•   updated man page to 0.21 or greater command line usage (fix debian #582494)

  What's New in Pylint 0.21.0?

Release date: 2010-05-11

•   command line updated (closes #9774, #9787, #9992, #22962):

•   all enable-* / disable-* options have been merged into --enable / --disable

•   BACKWARD INCOMPATIBLE CHANGE: short name of --errors-only becomes -E, -e being affected to --enable

•   pylint --help output much simplified, with --long-help available to get the complete one

•   revisited gui, thanks to students from Toronto university (they are great contributors to this release!)

•   fix #21591: html reporter produces no output if reports is set to 'no'

•   fix #4581: not Missing docstring (C0111) warning if a method is overridden

•   fix #4683: Non-ASCII characters count double if utf8 encode

•   fix #9018: when using defining-attr-method, method order matters

•   fix #4595: Comma not followed by a space should not occurs on trailing comma in list/tuple/dict definition

•   fix #22585: [Patch] fix man warnings for pyreverse.1 manpage

•   fix #20067: AttributeError: 'NoneType' object has no attribute 'name' with with

  What's New in Pylint 0.20.0?

Release date: 2010-03-01

•   fix #19498: fix windows batch file

•   fix #19339: pylint.el : non existing py-mod-map (closes Debian Bug report logs - #475939)

•   implement #18860, new W0199 message on assert (a, b)

•   implement #9776, 'W0150' break or return statement in finally block may swallow exception.

•   fix #9263, __init__ and __new__ are checked for unused arguments

•   fix #20991, class scope definitions ignored in a genexpr

•   fix #5975, Abstract intermediate class not recognized as such

•   fix #5977, yield and return statement have their own counters, no more R0911 (Too many return statements) when a function have many yield stamtements

•   implement #5564, function / method arguments with leading "_" are ignored in arguments / local variables count.

•   implement #9982, E0711 specific error message when raising NotImplemented

•   remove --cache-size option

  What's New in Pylint 0.19.0?

Release date: 2009-12-18

•   implement #18947, #5561: checker for function arguments

•   include James Lingard string format checker

•   include simple message (ids) listing by Vincent Ferotin (#9791)

•   --errors-only does not hide fatal error anymore

•   include james Lingard patches for ++/-- and duplicate key in dicts

•   include James Lingard patches for function call arguments checker

•   improved flymake code and doc provided by Derek Harland

•   refactor and fix the imports checker

•   fix #18862: E0601 false positive with lambda functions

•   fix #8764: More than one statement on a single line false positive with try/except/finally

•   fix #9215: false undefined variable error in lambda function

•   fix for w0108 false positive (Nathaniel)

•   fix test/fulltest.sh

•   #5821 added a utility function to run pylint in another process (patch provide by Vincent Ferotin)

  What's New in Pylint 0.18.0?

Release date: 2009-03-25

•   tests ok with python 2.4, 2.5, 2.6. 2.3 not tested

•   fix #8687, W0613 false positive on inner function

•   fix #8350, C0322 false positive on multi-line string

•   fix #8332: set E0501 line no to the first line where non ascii character has been found

•   avoid some E0203 / E0602 false negatives by detecting respectively AttributeError / NameError

•   implements #4037: don't issue W0142 (* or ** magic) when they are barely passed from /* arguments

•   complete #5573: more complete list of special methods, also skip W0613 for python internal method

•   don't show information messages by default

•   integration of Yuen Ho Wong's patches on emacs lisp files

  What's New in Pylint 0.17.0?

Release date: 2009-03-19

•   semicolon check : move W0601 to W0301

•   remove rpython : remove all rpython checker, modules and tests

•   astng 0.18 compatibility: support for _ast module modifies interfaces

  What's New in Pylint 0.16.0?

Release date: 2009-01-28

•   change [en|dis]able-msg-cat options: only accept message categories identified by their first letter (eg IRCWEF) without the need for comma as separator

•   add epylint.bat script to fix Windows installation

•   setuptools/easy_install support

•   include a modified version of Maarten ter Huurne patch to avoid W0613 warning on arguments from overridden method

•   implement #5575 drop dumb W0704 message) by adding W0704 to ignored messages by default

•   new W0108 message, checking for suspicious lambda (provided by Nathaniel Manista)

•   fix W0631, false positive reported by Paul Hachmann

•   fix #6951: false positive with W0104

•   fix #6949

•   patches by Mads Kiilerich:

•   implement #4691, make pylint exits with a non zero return status if any messages other then Information are issued

•   fix #3711, #5626 (name resolution bug w/ decorator and class members)

•   fix #6954

  What's New in Pylint 0.15.2?

Release date: 2008-10-13

•   fix #5672: W0706 weirdness ( W0706 removed )

•   fix #5998: documentation points to wrong url for mailing list

•   fix #6022: no error message on wrong module names

•   fix #6040: pytest doesn't run test/func_test.py

  What's New in Pylint 0.15.1?

Release date: 2008-09-15

•   fix #4910: default values are missing in manpage

•   fix #5991: missing files in 0.15.0 tarball

•   fix #5993: epylint should work with python 2.3

  What's New in Pylint 0.15.0?

Release date: 2008-09-10

•   include pyreverse package and class diagram generation

•   included Stefan Rank's patch to deal with 2.4 relative import

•   included Robert Kirkpatrick's tutorial and typos fixes

•   fix bug in reenabling message

•   fix #2473: invoking pylint on __init__.py (hopefully)

•   typecheck: acquired-members option has been dropped in favor of the more generic generated-members option. If the zope option is set, the behaviour is now to add some default values to generated-members.

•   flymake integration: added bin/epylint and elisp/pylint-flymake.el

  What's New in Pylint 0.14.0?

Release date: 2008-01-14

•   fix #3733: Messages (dis)appear depending on order of file names

•   fix #4026: pylint.el should require compile

•   fix a bug in colorized reporter, spotted by Dave Borowitz

•   applied patch from Stefan Rank to avoid W0410 false positive when multiple "from __future__" import statements

•   implement #4012: flag back tick as deprecated (new W0333 message)

•   new ignored-class option on typecheck checker allowing to skip members checking based on class name (patch provided by Thomas W Barr)

  What's New in Pylint 0.13.2?

Release date: 2007-06-07

•   fix disable-checker option so that it won't accidentally enable the rpython checker which is disabled by default

•   added note about the gedit plugin into documentation

  What's New in Pylint 0.13.1?

Release date: 2007-03-02

•   fix some unexplained 0.13.0 packaging issue which led to a bunch of files missing from the distribution

  What's New in Pylint 0.13.0?

Release date: 2007-02-28

•   new RPython (Restricted Python) checker for PyPy fellow or people wanting to get a compiled version of their python program using the translator of the PyPy project. For more information about PyPy or RPython, visit http://codespeak.net/pypy/

•   new E0104 and E0105 messages introduced to respectively warn about "return" and "yield" outside function or method

•   new E0106 message when "yield" and "return something" are mixed in a function or method

•   new W0107 message for unnecessary pass statement

•   new W0614 message to differentiate between unused import X and unused from X import * (#3209, patch submitted by Daniel Drake)

•   included Daniel Drake's patch to have a different message E1003 instead of E1001 when a missing member is found but an inference failure has been detected

•   msvs reporter for Visual Studio line number reporting (#3285)

•   allow disable-all option inline (#3218, patch submitted by Daniel Drake)

•   --init-hook option to call arbitrary code necessary to set environment (eg sys.path) (#3156)

•   One more Daniel's patch fixing a command line option parsing problem, this'll definitely be the DDrake release :)

•   fix #3184: crashes on "return" outside function

•   fix #3205: W0704 false positive

•   fix #3123: W0212 false positive on static method

•   fix #2485: W0222 false positive

•   fix #3259: when a message is explicitly enabled, check the checker emitting it is enabled

  What's New in Pylint 0.12.2?

Release date: 2006-11-23

•   fix #3143: W0233 bug w/ YES objects

•   fix #3119: Off-by-one error counting lines in a file

•   fix #3117: ease sys.stdout overriding for reporters

•   fix #2508: E0601 false positive with lambda

•   fix #3125: E1101 false positive and a message duplication. Only the last part is actually fixed since the initial false positive is due to dynamic setting of attributes on the decimal.Context class.

•   fix #3149: E0101 false positives and introduced E0100 for generator __init__ methods

•   fixed some format checker false positives

  What's New in Pylint 0.12.1?

Release date: 2006-09-25

•   fixed python >= 2.4 format false positive with multiple lines statement

•   fixed some 2.5 issues

•   fixed generator expression scope bug (depends on astng 0.16.1)

•   stop requiring __revision__

  What's New in Pylint 0.12.0?

Release date: 2006-08-10

•   usability changes:

•   parseable, html and color options are now handled by a single output-format option

•   enable-<checkerid> and disable-all options are now handled by two (exclusive) enable-checker and disable-checker options taking a comma separated list of checker names as value

•   renamed debug-mode option to errors-only

•   started a reference user manual

•   new W0212 message for access to protected member from client code (close #14081)

•   new W0105 and W0106 messages extracted from W0104 (statement seems to have no effect) respectively when the statement is actually string (that's sometimes used instead of comments for documentation) or an empty statement generated by a useless semicolon

•   reclassified W0302 to C0302

•   fix so that global messages are not anymore connected to the last analyzed module (close #10106)

•   fix some bugs related to local disabling of messages

•   fix cr/lf pb when generating the rc file on windows platforms

  What's New in Pylint 0.11.0?

Release date: 2006-04-19

•   fix crash caused by the exceptions checker in some case

•   fix some E1101 false positive with abstract method or classes defining __getattr__

•   dirty fix to avoid "_socketobject" has not "connect" member. The actual problem is that astng isn't able to understand the code used to create socket.socket object with exec

•   added an option in the similarity checker to ignore docstrings, enabled by default

•   included patch from Benjamin Niemann to allow block level enabling/disabling of messages

  What's New in Pylint 0.10.0?

Release date: 2006-03-06

•   WARNING, this release include some configuration changes (see below), so you may have to check and update your own configuration file(s) if you use one

•   this release require the 0.15 version of astng or superior (it will save you a lot of pylint crashes...)

•   W0705 has been reclassified to E0701, and is now detecting more inheriting problem, and a false positive when empty except clause is following an Exception catch has been fixed (close #10422)

•   E0212 and E0214 (metaclass/class method should have mcs/cls as first argument have been reclassified to C0202 and C0203 since this not as well established as "self" for instance method (E0213)

•   W0224 has been reclassified into F0220 (failed to resolve interfaces implemented by a class)

•   a new typecheck checker, introducing the following checks:

•   E1101, access to unexistent member (implements #10430), remove the need of E0201 and so some options has been moved from the classes checker to this one

•   E1102, calling a non callable object

•   E1111 and W1111 when an assignment is done on a function call but the inferred function returns None (implements #10431)

•   change in the base checker:

•   checks module level and instance attribute names (new const-rgx and attr-rgx configuration option) (implements #10209 and #10440)

•   list comprehension and generator expression variables have their own regular expression (the inlinevar-rgx option) (implements #9146)

•   the C0101 check with its min-name-length option has been removed (this can be specified in the regxp after all...)

•   W0103 and W0121 are now handled by the variables checker (W0103 is now W0603 and W0604 has been splitted into different messages)

•   W0131 and W0132 messages have been reclassified to C0111 and C0112 respectively

•   new W0104 message on statement without effect

•   regexp support for dummy-variables (dummy-variables-rgx option replace dummy-variables) (implements #10027)

•   better global statement handling, see W0602, W0603, W0604 messages (implements #10344 and #10236)

•   --debug-mode option, disabling all checkers without error message and filtering others to only display error

•   fixed some R0201 (method could be a function) false positive

  What's New in Pylint 0.9.0?

Release date: 2006-01-10

•   a lot of updates to follow astng 0.14 API changes, so install logilab-astng 0.14 or greater before using this version of pylint

•   checker number 10 ! newstyle will search for problems regarding old style / new style classes usage problems (rely on astng 0.14 new style detection feature)

•   new 'load-plugins' options to load additional pylint plugins (usable from the command line or from a configuration file) (implements #10031)

•   check if a "pylintrc" file exists in the current working directory before using the one specified in the PYLINTRC environment variable or the default ~/.pylintrc or /etc/pylintrc

•   fixed W0706 (Identifier used to raise an exception is assigned...) false positive and reraising a catched exception instance

•   fixed E0611 (No name get in module blabla) false positive when accessing to a class'__dict__

•   fixed some E0203 ("access to member before its definition") false positive

•   fixed E0214 ("metaclass method first argument should be mcs) false positive with staticmethod used on a metaclass

•   fixed packaging which was missing the test/regrtest_data directory

•   W0212 (method could be a function) has been reclassified in the REFACTOR category as R0201, and is no more considerer when a method overrides an abstract method from an ancestor class

•   include module name in W0401 (wildcard import), as suggested by Amaury

•   when using the '--parseable', path are written relative to the current working directory if in a sub-directory of it (#9789)

•   'pylint --version' shows logilab-astng and logilab-common versions

•   fixed pylint.el to handle space in file names

•   misc lint style fixes

  What's New in Pylint 0.8.1?

Release date: 2005-11-07

•   fix "deprecated module" false positive when the code imports a module whose name starts with a deprecated module's name (close #10061)

•   fix "module has no name __dict__" false positive (close #10039)

•   fix "access to undefined variable __path__" false positive (close #10065)

•   fix "explicit return in __init__" false positive when return is actually in an inner function (close #10075)

  What's New in Pylint 0.8.0?

Release date: 2005-10-21

•   check names imported from a module exists in the module (E0611), patch contributed by Amaury Forgeot d'Arc

•   print a warning (W0212) for methods that could be a function (implements #9100)

•   new --defining-attr-methods option on classes checker

•   new --acquired-members option on the classes checker, used when --zope=yes to avoid false positive on acquired attributes (listed using this new option) (close #8616)

•   generate one E0602 for each use of an undefined variable (previously, only one for the first use but not for the following) (implements #1000)

•   make profile option saveable

•   fix Windows .bat file, patch contributed by Amaury Forgeot d'Arc

•   fix one more false positive for E0601 (access before definition) with for loop such as "for i in range(10): print i" (test func_noerror_defined_and_used_on_same_line)

•   fix false positive for E0201 (undefined member) when accessing to __name__ on a class object

•   fix astng checkers traversal order

•   fix bug in format checker when parsing a file from a platform using different new line characters (close #9239)

•   fix encoding detection regexp

•   fix --rcfile handling (support for --rcfile=file, close #9590)

  What's New in Pylint 0.7.0?

Release date: 2005-05-27

•   WARNING: pylint is no longer a logilab subpackage. Users may have to manually remove the old logilab/pylint directory.

•   introduce a new --additional-builtins option to handle user defined builtins

•   --reports option has now -r as short alias, and -i for --include-ids

•   fix a bug in the variables checker which may causing some false positives when variables are defined and used within the same statement (test func_noerror_defined_and_used_on_same_line)

•   this time, real fix of the "disable-msg in the config file" problem, test added to unittest_lint

•   fix bug with --list-messages and python -OO

•   fix possible false positive for W0201

  What's New in Pylint 0.6.4?

Release date: 2005-04-14

•   allow to parse files without extension when a path is given on the command line (test noext)

•   don't fail if we are unable to read an inline option (e.g. inside a module), just produce an information message (test func_i0010)

•   new message E0103 for break or continue outside loop (close #8883, test func_continue_not_in_loop)

•   fix bug in the variables checker, causing non detection of some actual name error (close #8884, test func_nameerror_on_string_substitution)

•   fix bug in the classes checker which was making pylint crash if "object" is assigned in a class inheriting from it (test func_noerror_object_as_class_attribute)

•   fix problem with the similar checker when related options are defined in a configuration file

•   new --generate-man option to generate pylint's man page (require the latest logilab.common (>= 0.9.3)

•   packaged (generated...) man page

  What's New in Pylint 0.6.3?

Release date: 2005-02-24

•   fix scope problem which may cause false positive and true negative on E0602

•   fix problem with some options such as disable-msg causing error when they are coming from the configuration file

  What's New in Pylint 0.6.2?

Release date: 2005-02-16

•   fix false positive on E0201 ("access to undefined member") with metaclasses

•   fix false positive on E0203 ("access to member before its definition") when attributes are defined in a parent class

•   fix false positive on W0706 ("identifier used to raise an exception assigned to...")

•   fix interpretation of "t" as value for the indent-string configuration variable

•   fix --rcfile so that --rcfile=pylintrc (only --rcfile pylintrc was working in earlier release)

•   new raw checker example in the examples/ directory

  What's New in Pylint 0.6.1?

Release date: 2005-02-04

•   new --rcfile option to specify the configuration file without the PYLINTRC environment variable

•   added an example module for a custom pylint checker (see the example/ directory)

•   some fixes to handle fixes in common 0.9.1 (should however still working with common 0.9.0, even if upgrade is recommended)

  What's New in Pylint 0.6.0?

Release date: 2005-01-20

•   refix pylint emacs mode

•   no more traceback when just typing "pylint"

•   fix a bug which may cause crashes on resolving parent classes

•   fix problems with the format checker: don't chock on files containing multiple CR, avoid C0322, C0323, C0324 false positives with triple quoted string with quote inside

•   correctly detect access to member defined latter in __init__ method

•   now depends on common 0.8.1 to fix problem with interface resolution (close #8606)

•   new --list-msgs option describing available checkers and their messages

•   added windows specific documentation to the README file, contributed by Brian van den Broek

•   updated doc/features.txt (actually this file is now generated using the --list-msgs option), more entries into the FAQ

•   improved tests coverage

  What's New in Pylint 0.5.0?

Release date: 2004-10-19

•   avoid importing analyzed modules !

•   new Refactor and Convention message categories. Some Warnings have been remaped into those new categories

•   added "similar", a tool to find copied and pasted lines of code, both using a specific command line tool and integrated as a pylint's checker

•   imports checker may report import dependencies as a dot graph

•   new checker regrouping most Refactor detection (with some new metrics)

•   more command line options storable in the configuration file

•   fix bug with total / undocumented number of methods

  What's New in Pylint 0.4.2?

Release date: 2004-07-08

•   fix pylint emacs mode

•   fix classes checkers to handler twisted interfaces

  What's New in Pylint 0.4.1?

Release date: 2004-05-14

•   fix the setup.py script to allow bdist_winst (well, the generated installer has not been tested...) with the necessary logilab/__init__.py file

•   fix file naming convention as suggested by Andreas Amoroso

•   fix stupid crash bug with bad method names

  What's New in Pylint 0.4.0?

Release date: 2004-05-10

•   fix file path with --parsable

•   --parsable option has been renamed to --parseable

•   added patch from Andreas Amoroso to output message to files instead of standard output

•   added Run to the list of correct variable names

•   fix variable names regexp and checking of local classes names

•   some basic handling of metaclasses

•   no-docstring-rgx apply now on classes too

•   new option to specify a different regexp for methods than for functions

•   do not display the evaluation report when no statements has been analysed

•   fixed crash with a class nested in a method

•   fixed format checker to deals with triple quoted string and lines with code and comment mixed

•   use logilab.common.ureports to layout reports

  What's New in Pylint 0.3.3?

Release date: 2004-02-17

•   added a parsable text output, used when the --parsable option is provided

•   added an emacs mode using this output, available in the distrib's elisp directory

•   fixed some typos in messages

•   change include-ids options to yn, and allow it to be in the configuration file

•   do not chock on corrupted stats files

•   fixed bug in the format checker which may stop pylint execution

•   provide scripts for unix and windows to wrap the minimal pylint tk gui

  What's New in Pylint 0.3.2?

Release date: 2003-12-23

•   html-escape messages in the HTML reporter (bug reported by Juergen Hermann)

•   added "TODO" to the list of default note tags

•   added "rexec" to the list of default deprecated modules

•   fixed typos in some messages

  What's New in Pylint 0.3.1?

Release date: 2003-12-05

•   bug fix in format and classes checkers

•   remove print statement from imports checkers

•   provide a simple tk gui, essentially useful for windows users

  What's New in Pylint 0.3.0?

Release date: 2003-11-20

•   new exceptions checker, checking for string exception and empty except clauses.

•   imports checker checks for reimport of modules

•   classes checker checks for calls to ancestor's __init__ and abstract method not overridden. It doesn't complain anymore for unused import in __init__ files, and provides a new option ignore-interface-methods, useful when you're using zope Interface implementation in your project

•   base checker checks for disallowed builtins call (controlled by the bad-functions option) and for use of * and **

•   format checker checks for use of <> and "l" as long int marker

•   major internal API changes

•   use the rewrite of astng, based on compiler.ast

•   added unique id for messages, as suggested by Wolfgang Grafen

•   added unique id for reports

•   can take multiple modules or files as argument

•   new options command line options : --disable-msg, --enable-msg, --help-msg, --include-ids, --reports, --disable-report, --cache-size

•   --version shows the version of the python interpreter

•   removed some options which are now replaced by [en|dis]able-msg, or disable-report

•   read disable-msg and enable-msg options in source files (should be in comments on the top of the file, in the form "# pylint: disable-msg=W0402"

•   new message for modules importing themselves instead of the "cyclic import" message

•   fix bug with relative and cyclic imports

•   fix bug in imports checker (cycle was not always detected)

•   still fixes in format checker : don't check comment and docstring, check first line after an indent

•   allowed/prohibited names now apply to all identifiers, not only variables, so changed the configuration option from (good|bad)-variable-names to (good|bad)-names

•   added string, rexec and Bastion to the default list of deprecated modules

•   do not print redefinition warning for function/class/method defined in mutually exclusive branches

  What's New in Pylint 0.2.1?

Release date: 2003-10-10

•   added some documentation, fixed some typos

•   set environment variable PYLINT_IMPORT to 1 during pylint execution.

•   check that variables "imported" using the global statement exist

•   indentation problems are now warning instead of errors

•   fix checkers.initialize to try to load all files with a known python extension (patch from wrobell)

•   fix a bunch of messages

•   fix sample configuration file

•   fix the bad-construction option

•   fix encoding checker

•   fix format checker

  What's New in Pylint 0.2.0?

Release date: 2003-09-12

•   new source encoding / FIXME checker (pep 263)

•   new --zope option which trigger Zope import. Useful to check Zope products code.

•   new --comment option which enable the evaluation note comment (disabled by default).

•   a ton of bug fixes

•   easy functional test infrastructure

  What's New in Pylint 0.1.2?

Release date: 2003-06-18

•   bug fix release

•   remove dependency to pyreverse

  What's New in Pylint 0.1.1?

Release date: 2003-06-01

•   much more functionalities !

  What's New in Pylint 0.1?

Release date: 2003-05-19

•   initial release

AUTHOR
Logilab, PyCQA and contributors

COPYRIGHT
2003-2021, Logilab, PyCQA and contributors