doc/faq.rst - third_party/github.com/pylint-dev/pylint - Git at Google

 .. _faq:

 ==========================
 Frequently Asked Questions
 ==========================

 How do I install Pylint?
 ------------------------

 .. include:: short_text_installation.rst

 How do I contribute to Pylint?
 ------------------------------

 .. include:: short_text_contribute.rst


 Does Pylint follow a versioning scheme?
 ----------------------------------------

 See :ref:`upgrading pylint in the installation guide <upgrading_pylint>`.

 How do I find the name corresponding to a specific command line option?
 -----------------------------------------------------------------------

 See :ref:`the configuration documentation <all-configurations-options>`.

 What is the format of the configuration file?
 ---------------------------------------------

 The configuration file can be an ``ini`` or ``toml`` file. See the :ref:`exhaustive list of possible options <all-options>`.

 How to disable a particular message?
 ------------------------------------

 Read :ref:`message-control` for details and examples.

 Pylint gave my code a negative rating out of ten. That can't be right!
 ----------------------------------------------------------------------

 Prior to Pylint 2.13.0, the score formula used by default had no lower
 bound. The new default score formula is ::

     max(0, 0 if fatal else 10.0 - ((float(5 * error + warning + refactor + convention) / statement) * 10))

 If your project contains a configuration file created by an earlier version of
 Pylint, you can set ``evaluation`` to the above expression to get the new
 behavior. Likewise, since negative values are still technically supported,
 ``evaluation`` can be set to a version of the above expression that does not
 enforce a floor of zero.

 How do I avoid getting unused argument warnings for API I do not control?
 -------------------------------------------------------------------------

 Prefix (ui) the callback's name by `cb_` (callback), 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).


 Why are there a bunch of messages disabled by default?
 ------------------------------------------------------

 Either because they are prone to false positives or that they are opinionated enough
 to not be included as default messages.

 You can see the plugin you need to explicitly :ref:`load in the technical reference
 <user_guide/checkers/extensions:optional checkers>`.

 I want to run pylint on each keystroke in my IDE. How do I do that?
 ---------------------------------------------------------------------

 Pylint full suite of checks will never be fast enough to run on every keystroke.
 However, some IDEs can run pylint  when the IDE opens or saves files.
 See, for example, the `Microsoft plugin for VS Code`_.


 That said, pylint is best suited for linting on save for small projects, for continuous
 integration jobs, or a git ``pre-push`` hook for big projects. The larger your repository
 is, the slower pylint will be.

 If you want to make pylint faster for this type of use case, you can use the ``--errors-only``
 option, which will remove all the refactor, convention, and warning checks. You can also disable
 checks with inherently high complexity that need to analyse the full code base like
 ``duplicate-code`` or ``cyclic-import`` (this list is not exhaustive).

 .. _`Microsoft plugin for VS Code`: https://github.com/microsoft/vscode-pylint#readme

 Why do I have non-deterministic results when I try to parallelize pylint ?
 --------------------------------------------------------------------------

 pylint should analyse all your code at once in order to best infer the
 actual values that result from calls. If only some of the files are given, pylint might
 miss a particular value's type and produce inferior inference for the subset. Parallelization
 of pylint is not easy; we also discourage the use of the ``-j`` option if this matters to you.


 Which messages should I disable to avoid duplicates if I use other popular linters ?
 ------------------------------------------------------------------------------------

 pycodestyle_: bad-indentation, bare-except, line-too-long, missing-final-newline, multiple-statements, singleton-comparison, trailing-newlines, trailing-whitespace, unnecessary-negation, unnecessary-semicolon, wrong-import-position

 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_ and flake8-import-order_: ungrouped-imports, wrong-import-order

 .. _`pycodestyle`: https://github.com/PyCQA/pycodestyle
 .. _`pyflakes`: https://github.com/PyCQA/pyflakes
 .. _`mccabe`: https://github.com/PyCQA/mccabe
 .. _`pydocstyle`: https://github.com/PyCQA/pydocstyle
 .. _`pep8-naming`: https://github.com/PyCQA/pep8-naming
 .. _`isort`: https://github.com/pycqa/isort
 .. _`flake8-import-order`: https://github.com/PyCQA/flake8-import-order

 How do I avoid "access to undefined member" messages in my mixin classes?
 -------------------------------------------------------------------------

 You should add the ``no-member`` message to your ``ignored-checks-for-mixins`` option
 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.

 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"
     - macOS: "~/Library/Caches/pylint"
     - Windows: "C:\Users\<username>\AppData\Local\pylint"
 * ".pylint.d" directory in the current directory

 How does the website pylint dot org relate to this project?
 -----------------------------------------------------------

 Historically, pylint dot org served as the primary website for Pylint. However,
 we no longer have access to the domain. The current owners are monetizing
 this by displaying advertisements alongside outdated documentation without
 contributing to pylint at all. For the latest and official Pylint documentation,
 please visit `pylint.readthedocs.io <https://pylint.readthedocs.io/en/stable/>`_.

 Please see `issue 8934 <https://github.com/pylint-dev/pylint/issues/8934>`_
 for more details.
	.. _faq:

	==========================
	Frequently Asked Questions
	==========================

	How do I install Pylint?
	------------------------

	.. include:: short_text_installation.rst

	How do I contribute to Pylint?
	------------------------------

	.. include:: short_text_contribute.rst


	Does Pylint follow a versioning scheme?
	----------------------------------------

	See :ref:`upgrading pylint in the installation guide <upgrading_pylint>`.

	How do I find the name corresponding to a specific command line option?
	-----------------------------------------------------------------------

	See :ref:`the configuration documentation <all-configurations-options>`.

	What is the format of the configuration file?
	---------------------------------------------

	The configuration file can be an ``ini`` or ``toml`` file. See the :ref:`exhaustive list of possible options <all-options>`.

	How to disable a particular message?
	------------------------------------

	Read :ref:`message-control` for details and examples.

	Pylint gave my code a negative rating out of ten. That can't be right!
	----------------------------------------------------------------------

	Prior to Pylint 2.13.0, the score formula used by default had no lower
	bound. The new default score formula is ::

	max(0, 0 if fatal else 10.0 - ((float(5 * error + warning + refactor + convention) / statement) * 10))

	If your project contains a configuration file created by an earlier version of
	Pylint, you can set ``evaluation`` to the above expression to get the new
	behavior. Likewise, since negative values are still technically supported,
	``evaluation`` can be set to a version of the above expression that does not
	enforce a floor of zero.

	How do I avoid getting unused argument warnings for API I do not control?
	-------------------------------------------------------------------------

	Prefix (ui) the callback's name by `cb_` (callback), 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).


	Why are there a bunch of messages disabled by default?
	------------------------------------------------------

	Either because they are prone to false positives or that they are opinionated enough
	to not be included as default messages.

	You can see the plugin you need to explicitly :ref:`load in the technical reference
	<user_guide/checkers/extensions:optional checkers>`.

	I want to run pylint on each keystroke in my IDE. How do I do that?
	---------------------------------------------------------------------

	Pylint full suite of checks will never be fast enough to run on every keystroke.
	However, some IDEs can run pylint when the IDE opens or saves files.
	See, for example, the `Microsoft plugin for VS Code`_.


	That said, pylint is best suited for linting on save for small projects, for continuous
	integration jobs, or a git ``pre-push`` hook for big projects. The larger your repository
	is, the slower pylint will be.

	If you want to make pylint faster for this type of use case, you can use the ``--errors-only``
	option, which will remove all the refactor, convention, and warning checks. You can also disable
	checks with inherently high complexity that need to analyse the full code base like
	``duplicate-code`` or ``cyclic-import`` (this list is not exhaustive).

	.. _`Microsoft plugin for VS Code`: https://github.com/microsoft/vscode-pylint#readme

	Why do I have non-deterministic results when I try to parallelize pylint ?
	--------------------------------------------------------------------------

	pylint should analyse all your code at once in order to best infer the
	actual values that result from calls. If only some of the files are given, pylint might
	miss a particular value's type and produce inferior inference for the subset. Parallelization
	of pylint is not easy; we also discourage the use of the ``-j`` option if this matters to you.


	Which messages should I disable to avoid duplicates if I use other popular linters ?
	------------------------------------------------------------------------------------

	pycodestyle_: bad-indentation, bare-except, line-too-long, missing-final-newline, multiple-statements, singleton-comparison, trailing-newlines, trailing-whitespace, unnecessary-negation, unnecessary-semicolon, wrong-import-position

	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_ and flake8-import-order_: ungrouped-imports, wrong-import-order

	.. _`pycodestyle`: https://github.com/PyCQA/pycodestyle
	.. _`pyflakes`: https://github.com/PyCQA/pyflakes
	.. _`mccabe`: https://github.com/PyCQA/mccabe
	.. _`pydocstyle`: https://github.com/PyCQA/pydocstyle
	.. _`pep8-naming`: https://github.com/PyCQA/pep8-naming
	.. _`isort`: https://github.com/pycqa/isort
	.. _`flake8-import-order`: https://github.com/PyCQA/flake8-import-order

	How do I avoid "access to undefined member" messages in my mixin classes?
	-------------------------------------------------------------------------

	You should add the ``no-member`` message to your ``ignored-checks-for-mixins`` option
	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.

	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"
	- macOS: "~/Library/Caches/pylint"
	- Windows: "C:\Users\<username>\AppData\Local\pylint"
	* ".pylint.d" directory in the current directory

	How does the website pylint dot org relate to this project?
	-----------------------------------------------------------

	Historically, pylint dot org served as the primary website for Pylint. However,
	we no longer have access to the domain. The current owners are monetizing
	this by displaying advertisements alongside outdated documentation without
	contributing to pylint at all. For the latest and official Pylint documentation,
	please visit `pylint.readthedocs.io <https://pylint.readthedocs.io/en/stable/>`_.

	Please see `issue 8934 <https://github.com/pylint-dev/pylint/issues/8934>`_
	for more details.