python3 formatting with black

TOC

I see formatting consistency provided by the black command helps me.

The black is available as Debian package and its upstream is at https://github.com/psf/black

Lint tools before black

These are basic lint tools before black.

• pycodestyle (formerly called pep8)
• flake8 (bundle of: pycodestyle + pyflakes).

Install black

 $ sudo apt install python3-black

Use black

 $ black a-python-code-directory/

or

 $ black a-python-code-file.py

Skip Lint prigram

Line with #NOQA at the end are skipped by pycodestyle for PEP-8 lint.

Lines between # fmt: off and # fmt: on are skipped by the black.

Make black to work with other tools

Adding followings to pyproject.toml may be useful.

[flake8]
max-line-length = 88
select = C,E,F,W,B,B950
ignore = E203,W503,W504

[tool.isort]
include_trailing_comma = true
line_length = 88
multi_line_output = 3

Here:

• max-line-length per line
  • Black default is 88 ch/line https://github.com/psf/black#line-length
  • Ignore E501 for line too long (82 > 79 characters)
• pep8 Warning / Error codes
  • E203 for https://github.com/psf/black#slices
  • W503 for https://github.com/psf/black#line-breaks--binary-operators
  • W504 for line break after binary operator (default ignored)

Other programs

• isort is a Python utility / library to sort imports alphabetically, and automatically separated into sections.
• flake8-black is a flake8 plugin for validating Python code style with the command line code formatting tool black.