Flake8

Documentation:

• http://flake8.pycqa.org/en/latest/

Install:

pip install flake8

To use it for a folder:

# for the current path
flake8
# or
python -m flake8
# or
flake8 /the/path

To use it for a file:

flake8 path/to/file.py

The output format is:
file path : line number : column number : error code : short description

Flake8 will exit with code 1 if there are errors. You can change this using the parameter: --exit-zero

Error code prefix:

• E*/W*: pep8 errors and warnings ─ https://pep8.readthedocs.io/en/latest/intro.html#error-codes
• F*: PyFlakes codes ─ https://flake8.pycqa.org/en/latest/user/error-codes.html
• C9*: McCabe complexity plugin mccabe
• N8*: Naming Conventions plugin pep8-naming ─ https://github.com/PyCQA/pep8-naming

You can configure the flake8 analysis using its command parameters (http://flake8.pycqa.org/en/latest/user/options.html) or placing them in a file named setup.cfg in the project root.

[flake8]
exclude = .git,*migrations*
max-line-length = 119

Just add # noqa in the end of the line.

def ready(self):
    import cmdbox.profiles.signals.handlers  # noqa

Or you can pass the specific error code you want to ignore:

import cmdbox.profiles.signals.handlers  # noqa: F401

• Pycharm
  • https://foxmask.net/post/2016/02/17/pycharm-running-flake8/
  • https://gist.github.com/tossmilestone/23139d870841a3d5cba2aea28da1a895
• Atom
  • https://atom.io/packages/linter-flake8
• Vim
  • https://github.com/nvie/vim-flake8
• SublimeText
  • https://github.com/dreadatour/Flake8Lint
  • https://github.com/SublimeLinter/SublimeLinter-flake8
• Visual Studio Code
  • https://code.visualstudio.com/docs/python/linting

Parameters:

• --count to print the number of errors.
• --select=E4,E51,W234 to select which errors analyse.
• --ignore=E4,E51,W234 to select which errors ignore.
• --show-source to show the code where the error was found.
• --output-file=OUTPUT_FILE to redirect the output to a text file.
• --config=CONFIG to select the config file.
• --statistics to show statistics about errors and warnings.

http://flake8.pycqa.org/en/latest/user/using-hooks.html

You can stop a commit if flake8 find errors.

To see which plugins are enabled:

flake8 --version

To temporally enable disabled plugins: --enabled-extensions=ENABLED_EXTENSIONS.