2020-01-10 00:25:38 +00:00
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.. -*- coding: utf-8 -*-
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How To Write a Pylint Plugin
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============================
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Pylint provides support for writing two types of extensions.
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First, there is the concept of **checkers**,
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which can be used for finding problems in your code.
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Secondly, there is also the concept of **transform plugin**,
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which represents a way through which the inference and
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the capabilities of Pylint can be enhanced
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and tailored to a particular module, library of framework.
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In general, a plugin is a module which should have a function ``register``,
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which takes an instance of ``pylint.lint.PyLinter`` as input.
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A plugin can optionally define also function ``load_configuration``,
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which takes an instance of ``pylint.lint.PyLinter`` as input. This
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function is called after Pylint loads configuration from configuration
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file and command line interface. This function should load additional
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plugin specific configuration to Pylint.
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So a basic hello-world plugin can be implemented as:
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.. sourcecode:: python
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# Inside hello_plugin.py
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def register(linter):
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print 'Hello world'
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We can run this plugin by placing this module in the PYTHONPATH and invoking
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**pylint** as:
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.. sourcecode:: bash
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$ pylint -E --load-plugins hello_plugin foo.py
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Hello world
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We can extend hello-world plugin to ignore some specific names using
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``load_configuration`` function:
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.. sourcecode:: python
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# Inside hello_plugin.py
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def register(linter):
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print 'Hello world'
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def load_configuration(linter):
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name_checker = get_checker(linter, NameChecker)
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# We consider as good names of variables Hello and World
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name_checker.config.good_names += ('Hello', 'World')
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# We ignore bin directory
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linter.config.black_list += ('bin',)
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Depending if we need a **transform plugin** or a **checker**, this might not
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be enough. For the former, this is enough to declare the module as a plugin,
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but in the case of the latter, we need to register our checker with the linter
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object, by calling the following inside the ``register`` function::
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linter.register_checker(OurChecker(linter))
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For more information on writing a checker see :ref:`write_a_checker`.
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