Flake8-pyproject / flake8p

Runs Flake8 with configuration from pyproject.toml

Flake8 cannot be configured via pyproject.toml, even though virtually all other Python dev tools have adopted it as the central location for project configuration. The discussion of the original proposal (#234) was closed as "too heated", subsequent feature and pull requests were marked as "spam" (#1332, #1421, #1431, #1447, #1501).

Flake8-pyproject also has bad manners and force-feeds Flake8 the spam it so despises. It is inspired by pyproject-Flake8, which had received little maintenance following its initial commit. The code was however completely rewritten and a simple test suite makes it all a little more palatable.

Usage

Say your Flake8 configuration in .flake8 (or in tox.ini, or setup.cfg) is this:

[flake8]
ignore = E231, E241
per-file-ignores =
    __init__.py:F401
max-line-length = 88
count = true

Copy that [flake8] section to pyproject.toml, rename it as [tool.flake8], and convert the key–value pairs to the TOML format:

[tool.flake8]
ignore = ['E231', 'E241']
per-file-ignores = [
    '__init__.py:F401',
]
max-line-length = 88
count = true

From then on run flake8p instead of flake8 to lint the code so that the configuration in pyproject.toml will be used.

Implementation

Flake8 uses RawConfigParser from the standard library to parse its configuration files, and therefore expects them to have the INI format.

This library adds pyproject.toml to Flake8's list of acceptable configuration files and monkey-patches Flake8's RawConfigParser class definition so that, when pyproject.toml is being read, the format is converted from TOML to INI on the fly. TOML parsing is handled by Tomli, which will be part of the standard library as of Python 3.11 (PEP 680).

A few very simple integration tests round out the package, making sure that any one of the possible configuration files are in fact accepted.