Base Python Config: pre-commit hooks and pyproject.toml

.pre-commit-config.yaml

repos:
  - repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v3.4.0
    hooks:
      - id: end-of-file-fixer
      - id: trailing-whitespace
  - repo: https://github.com/psf/black
    rev: 21.11b1
    hooks:
      - id: black
  - repo: https://gitlab.com/pycqa/flake8
    rev: 4.0.1
    hooks:
      - id: flake8
        exclude: samples/
  - repo: https://github.com/timothycrosley/isort
    rev: 5.10.1
    hooks:
      - id: isort
  - repo: https://github.com/pre-commit/mirrors-mypy
    rev: v0.910
    hooks:
      - id: mypy
        additional_dependencies: [types-toml==0.1.3]
  - repo: https://github.com/guilatrova/tryceratops
    rev: v1.0.0
    hooks:
      - id: tryceratops

pyproject.toml

[tool.poetry]
...
packages = [
    { include = "PACKAGE_NAME", from = "src" },
]

[tool.black]
line-length = 120

[tool.isort]
profile = "black"
line_length = 120
extra_standard_library = ["pytest"]

[tool.mypy]
ignore_missing_imports = true

setup.cfg

[flake8]
max-line-length=120
extend-ignore=E203
exclude=
    __init__.py

Pre-commit config

This template uses the following linters:

Linter	Reason
black	Formatting
flake8	General linting (e.g. unused variables)
isort	Sort of imports
mypy	Typing validation
tryceratops	Avoid try/except anti-patterns
end-of-file-fixer / trailing-whitespace	General clean up

pyproject.toml

line length

I don't have strong opinions about line length, but 88 is often too short. The challenge is to keep all linters "agree" with each other, so the above model ensures it's 120 as default and makes it obvious for you to replace it with any other number you prefer.

packages

When testing a CLI or related package that I need to import globally, it's useful to add this section to make poetry install your package. (Similar to pip install -e .).

extra_standard_library

I feel pytest is often part of the standard python lib (it's not), so it makes me comfortable to keep it at the top when sorting.

ignore_missing_imports

When this flag is disable mypy can get really noisy.

setup.cfg

The only purpose of this file is because flake8 still doesn't support pyproject.toml.