| name | setting-up-python-libraries |
| description | Sets up professional Python library projects with modern tooling (pyproject.toml, uv, ruff, pytest, pre-commit, GitHub Actions). Use when creating new Python libraries, modernizing existing projects to pyproject.toml, configuring linting/testing/CI, or setting up Makefiles and pre-commit hooks. |
Python Library Project Setup
Quick Start
Create a new library with this structure:
my-library/
├── src/my_library/
│ ├── __init__.py
│ └── py.typed
├── tests/
├── pyproject.toml
├── Makefile
├── .pre-commit-config.yaml
└── .github/workflows/ci.yml
Use src/ layout to prevent accidental imports of development code.
Core Configuration
For complete templates, see:
- PYPROJECT.md - Full pyproject.toml with all tool configs
- CI.md - GitHub Actions and pre-commit setup
- MAKEFILE.md - Makefile automation patterns
Minimal pyproject.toml
[build-system]
requires = ["setuptools>=61.0", "wheel"]
build-backend = "setuptools.build_meta"
[project]
name = "my-library"
version = "0.1.0"
description = "What it does"
readme = "README.md"
requires-python = ">=3.10"
license = {text = "MIT"}
dependencies = []
[project.optional-dependencies]
dev = ["pytest>=7.0", "ruff>=0.1", "mypy>=1.0"]
[tool.setuptools.packages.find]
where = ["src"]
Essential Commands
pip install -e ".[dev]"
pre-commit install
ruff check src tests
ruff format src tests
pytest
mypy src
Key Decisions
| Choice | Recommendation | Why |
|---|
| Layout | src/ | Catches packaging bugs early |
| Build backend | setuptools | Mature, broad compatibility |
| Linter | ruff | Fast, replaces flake8+isort+black |
| Python range | >=3.10 | Don't pin exact versions |
| Dependencies | Minimal | Move optional deps to extras |
Checklist
Project Setup:
- [ ] src/ layout with py.typed marker
- [ ] pyproject.toml (not setup.py)
- [ ] Makefile with dev/test/lint/format
- [ ] .pre-commit-config.yaml
- [ ] .github/workflows/ci.yml
- [ ] README.md, LICENSE, CHANGELOG.md
- [ ] .gitignore
Helper Script
Create a new project structure:
python scripts/create_project.py my-library --author "Name"
Learn More
This skill is based on the Guide to Developing High-Quality Python Libraries by Will McGinnis. See these posts for deeper coverage:
