Pylint_

.. _Pylint: https://pylint.readthedocs.io/

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What is Pylint?

Pylint is a static code analyser_ for Python 2 or 3. The latest version supports Python 3.11.0 and above.

.. _static code analyser: https://en.wikipedia.org/wiki/Static_code_analysis

Pylint analyses your code without actually running it. It checks for errors, enforces a coding standard, looks for code smells_, and can make suggestions about how the code could be refactored.

.. _code smells: https://martinfowler.com/bliki/CodeSmell.html

Install

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For command line use, pylint is installed with::

pip install pylint

Or if you want to also check spelling with enchant (you might need to install the enchant C library <https://pyenchant.github.io/pyenchant/install.html#installing-the-enchant-c-library>_):

.. code-block:: sh

pip install pylint[spelling]

It can also be integrated in most editors or IDEs. More information can be found in the documentation_.

.. _in the documentation: https://pylint.readthedocs.io/en/latest/user_guide/installation/index.html

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What differentiates Pylint?

Pylint is not trusting your typing and is inferring the actual values of nodes (for a start because there was no typing when pylint started off) using its internal code representation (astroid). If your code is import logging as argparse, Pylint can check and know that argparse.error(...) is in fact a logging call and not an argparse call. This makes pylint slower, but it also lets pylint find more issues if your code is not fully typed.

[inference] is the killer feature that keeps us using [pylint] in our project despite how painfully slow it is.
- `Realist pylint user`_, 2022

.. _Realist pylint user: https://github.com/charliermarsh/ruff/issues/970#issuecomment-1381067064

pylint, not afraid of being a little slower than it already is, is also a lot more thorough than other linters. There are more checks, including some opinionated ones that are deactivated by default but can be enabled using configuration.

How to use pylint

Pylint isn't smarter than you: it may warn you about things that you have conscientiously done or check for some things that you don't care about. During adoption, especially in a legacy project where pylint was never enforced, it's best to start with the --errors-only flag, then disable convention and refactor messages with --disable=C,R and progressively re-evaluate and re-enable messages as your priorities evolve.

Pylint is highly configurable and permits to write plugins in order to add your own checks (for example, for internal libraries or an internal rule). Pylint also has an ecosystem of existing plugins for popular frameworks and third-party libraries.

.. note::

Pylint supports the Python standard library out of the box. Third-party
libraries are not always supported, so a plugin might be needed. A good place
to start is ``PyPI`` which often returns a plugin by searching for
``pylint <library>``. `pylint-pydantic`_, `pylint-django`_ and
`pylint-sonarjson`_ are examples of such plugins. More information about plugins
and how to load them can be found at `plugins`_.

.. _plugins: https://pylint.readthedocs.io/en/latest/development_guide/how_tos/plugins.html#plugins .. _pylint-pydantic: https://pypi.org/project/pylint-pydantic .. _pylint-django: https://github.com/pylint-dev/pylint-django .. _pylint-sonarjson: https://github.com/cnescatlab/pylint-sonarjson-catlab

Advised linters alongside pylint

Projects that you might want to use alongside pylint include ruff_ (really fast, with builtin auto-fix and a large number of checks taken from popular linters, but implemented in rust) or flake8_ (a framework to implement your own checks in python using ast directly), mypy_, pyright_ / pylance or pyre_ (typing checks), bandit_ (security oriented checks), black_ and isort_ (auto-formatting), autoflake_ (automated removal of unused imports or variables), pyupgrade_ (automated upgrade to newer python syntax) and pydocstringformatter_ (automated pep257).

.. _ruff: https://github.com/astral-sh/ruff .. _flake8: https://github.com/PyCQA/flake8 .. _bandit: https://github.com/PyCQA/bandit .. _mypy: https://github.com/python/mypy .. _pyright: https://github.com/microsoft/pyright .. _pyre: https://github.com/facebook/pyre-check .. _black: https://github.com/psf/black .. _autoflake: https://github.com/myint/autoflake .. _pyupgrade: https://github.com/asottile/pyupgrade .. _pydocstringformatter: https://github.com/DanielNoord/pydocstringformatter .. _isort: https://pycqa.github.io/isort/

Additional tools included in pylint

Pylint ships with two additional tools:

• pyreverse_ (standalone tool that generates package and class diagrams.)
• symilar_ (duplicate code finder that is also integrated in pylint)

.. _pyreverse: https://pylint.readthedocs.io/en/latest/additional_tools/pyreverse/index.html .. _symilar: https://pylint.readthedocs.io/en/latest/additional_tools/symilar/index.html

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Contributing

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We welcome all forms of contributions such as updates for documentation, new code, checking issues for duplicates or telling us that we can close them, confirming that issues still exist, creating issues because you found a bug or want a feature_, etc. Everything is much appreciated!

Please follow the code of conduct_ and check the Contributor Guides_ if you want to make a code contribution.

.. _creating issues because you found a bug or want a feature: https://pylint.readthedocs.io/en/latest/contact.html#bug-reports-feedback .. _code of conduct: https://github.com/pylint-dev/pylint/blob/main/CODE_OF_CONDUCT.md .. _the Contributor Guides: https://pylint.readthedocs.io/en/latest/development_guide/contribute.html

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Show your usage

You can place this badge in your README to let others know your project uses pylint.

.. image:: https://img.shields.io/badge/linting-pylint-yellowgreen
    :target: https://github.com/pylint-dev/pylint

Learn how to add a badge to your documentation in the badge documentation_.

.. _the badge documentation: https://pylint.readthedocs.io/en/latest/user_guide/installation/badge.html

License

pylint is, with a few exceptions listed below, GPLv2 <https://github.com/pylint-dev/pylint/blob/main/LICENSE>_.

The icon files are licensed under the CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0/>_ license:

• doc/logo.png <https://raw.githubusercontent.com/pylint-dev/pylint/main/doc/logo.png>_
• doc/logo.svg <https://raw.githubusercontent.com/pylint-dev/pylint/main/doc/logo.svg>_

Support

Please check the contact information_.

.. _the contact information: https://pylint.readthedocs.io/en/latest/contact.html

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• • |tideliftlogo|
  • 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.

.. _Tidelift Subscription: https://tidelift.com/subscription/pkg/pypi-pylint?utm_source=pypi-pylint&utm_medium=referral&utm_campaign=readme