Flake8 - Octo-Ninja Linter

Main point

Flake8 combines so much linter-power under the hood of a single tool! If used correctly, it will make your code not only more consistent, but simply better (and more pythonic 🐍).

• Flake8 is a wrapper around three tools:

  1. PyFlakes - checks for Python errors.
  2. pycodestyle - tests Python code against some of the style conventions in PEP 8.
  3. McCabe - analyses Python code complexity (see the next section for more details).

• Flake8 is configurable, where specific setup can be pointed in a couple of ways.

  • You may find preconfigured .flake8 in Big-Bang-py.

• There is an abundance of plugins greatly extending capability of Flake8. Search for them on GitHub.

  • A bunch of plugins are included in Flake8 configuration of Big-Bang-py. See all flake8-* packages in dev.in file.
  • An interesting example is flake8-html, which generates readable Flake8 HTML report (works similar to coverage html).

• It is recommended to include Flake8 in your linting Invoke task and also to run it during Pre-commit Git Hook. Example of both can be found in Big-Bang-py, see project.py and Pre-commit.

• To manage edge cases, exclude Flake8 checking:

  1. per code line;
  2. per entire file;
  3. per combination of file & error code;
  4. per particular error.

  Option 3 & 4 are best set in Flake8 config. See an example below:

  ignore =
      # C408: Unnecessary (dict/list/tuple) call - rewrite as a literal
      #
      # Calling directly dict/list/tuple is more obvious & explicit, making it
      # easier to read.
      C408,
  
      # C812 missing trailing comma
      #
      # Experience shows that this can be seriously inconvenient.
      C812
  
  per-file-ignores =
    ci/ci_checks.py: T001
    tasks/release.py: T001