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|
.. _register-a-plugin:
==================================
Registering a Plugin with Flake8
==================================
To register any kind of plugin with |Flake8|, you need:
#. A way to install the plugin (whether it is packaged on its own or
as part of something else). In this section, we will use a ``setup.py``
written for an example plugin.
#. A name for your plugin that will (ideally) be unique.
#. A somewhat recent version of setuptools (newer than 0.7.0 but preferably as
recent as you can attain).
|Flake8| relies on functionality provided by setuptools called
`Entry Points`_. These allow any package to register a plugin with |Flake8|
via that package's ``setup.py`` file.
Let's presume that we already have our plugin written and it's in a module
called ``flake8_example``. We might have a ``setup.py`` that looks something
like:
.. code-block:: python
from __future__ import with_statement
import setuptools
requires = [
"flake8 > 3.0.0",
]
flake8_entry_point = # ...
setuptools.setup(
name="flake8_example",
license="MIT",
version="0.1.0",
description="our extension to flake8",
author="Me",
author_email="example@example.com",
url="https://gitlab.com/me/flake8_example",
packages=[
"flake8_example",
],
install_requires=requires,
entry_points={
flake8_entry_point: [
'X = flake8_example:ExamplePlugin',
],
},
classifiers=[
"Framework :: Flake8",
"Environment :: Console",
"Intended Audience :: Developers",
"License :: OSI Approved :: MIT License",
"Programming Language :: Python",
"Programming Language :: Python :: 2",
"Programming Language :: Python :: 3",
"Topic :: Software Development :: Libraries :: Python Modules",
"Topic :: Software Development :: Quality Assurance",
],
)
Note specifically these lines:
.. code-block:: python
flake8_entry_point = # ...
setuptools.setup(
# snip ...
entry_points={
flake8_entry_point: [
'X = flake8_example:ExamplePlugin',
],
},
# snip ...
)
We tell setuptools to register our entry point ``X`` inside the specific
grouping of entry-points that flake8 should look in.
|Flake8| presently looks at three groups:
- ``flake8.extension``
- ``flake8.listen``
- ``flake8.report``
If your plugin is one that adds checks to |Flake8|, you will use
``flake8.extension``. If your plugin automatically fixes errors in code, you
will use ``flake8.listen``. Finally, if your plugin performs extra report
handling (formatting, filtering, etc.) it will use ``flake8.report``.
If our ``ExamplePlugin`` is something that adds checks, our code would look
like:
.. code-block:: python
setuptools.setup(
# snip ...
entry_points={
'flake8.extension': [
'X = flake8_example:ExamplePlugin',
],
},
# snip ...
)
The ``X`` in checking plugins define what error codes it is going to report.
So if the plugin reports only the error code ``X101`` your entry-point would
look like::
X101 = flake8_example.ExamplePlugin
If your plugin reports several error codes that all start with ``X10``, then
it would look like::
X10 = flake8_example.ExamplePlugin
If all of your plugin's error codes start with ``X1`` then it would look
like::
X1 = flake8_example.ExamplePlugin
Finally, if all of your plugin's error codes start with just ``X`` then it
would look like the original example.
.. _Entry Points:
https://pythonhosted.org/setuptools/pkg_resources.html#entry-points
|
