third_party.pylibs.pylint.src/doc/plugins.rst

.. -*- coding: utf-8 -*-

================
Extending Pylint
================

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 is 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.

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

.. sourcecode:: python

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

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

.. sourcecode:: bash

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

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))


.. toctree::
   :maxdepth: 2
   :titlesonly:

   custom_checkers
   transform_plugins