| ====== |
| Flake8 |
| ====== |
| |
| Flake8 is a wrapper around these tools: |
| |
| - PyFlakes |
| - pep8 |
| - Ned Batchelder's McCabe script |
| |
| Flake8 runs all the tools by launching the single ``flake8`` script. |
| It displays the warnings in a per-file, merged output. |
| |
| It also adds a few features: |
| |
| - files that contain this line are skipped:: |
| |
| # flake8: noqa |
| |
| - lines that contain a ``# noqa`` comment at the end will not issue warnings. |
| - a Git and a Mercurial hook. |
| - a McCabe complexity checker. |
| - extendable through ``flake8.extension`` entry points. |
| |
| |
| QuickStart |
| ========== |
| |
| :: |
| |
| pip install flake8 |
| |
| To run flake8 just invoke it against any directory or Python module:: |
| |
| $ flake8 coolproject |
| coolproject/mod.py:97:1: F401 'shutil' imported but unused |
| coolproject/mod.py:625:17: E225 missing whitespace around operato |
| coolproject/mod.py:729:1: F811 redefinition of function 'readlines' from line 723 |
| coolproject/mod.py:1028:1: F841 local variable 'errors' is assigned to but never used |
| |
| The outputs of PyFlakes *and* pep8 (and the optional plugins) are merged |
| and returned. |
| |
| flake8 offers an extra option: --max-complexity, which will emit a warning if |
| the McCabe complexity of a function is higher than the value. By default it's |
| deactivated:: |
| |
| $ flake8 --max-complexity 12 coolproject |
| coolproject/mod.py:97:1: F401 'shutil' imported but unused |
| coolproject/mod.py:625:17: E225 missing whitespace around operator |
| coolproject/mod.py:729:1: F811 redefinition of unused 'readlines' from line 723 |
| coolproject/mod.py:939:1: C901 'Checker.check_all' is too complex (12) |
| coolproject/mod.py:1028:1: F841 local variable 'errors' is assigned to but never used |
| coolproject/mod.py:1204:1: C901 'selftest' is too complex (14) |
| |
| This feature is quite useful to detect over-complex code. According to McCabe, |
| anything that goes beyond 10 is too complex. |
| See https://en.wikipedia.org/wiki/Cyclomatic_complexity. |
| |
| Questions or Feedback |
| ===================== |
| |
| If you have questions you'd like to ask the developers, or feedback you'd like |
| to provide, feel free to use the mailing list: code-quality@python.org We |
| would love to hear from you. Additionally, if you have a feature you'd like to |
| suggest, the mailing list would be the best place for it. |
| |
| .. _links: |
| |
| Links |
| ===== |
| |
| * `flake8 documentation <http://flake8.readthedocs.org/en/latest/>`_ |
| |
| * `pep8 documentation <http://pep8.readthedocs.org/en/latest/>`_ |
