python-packaging

Python Packaging

Comprehensive guide to creating, structuring, and distributing Python packages using modern packaging tools, pyproject.toml, and publishing to PyPI.

When to Use This Skill

• Creating Python libraries for distribution
• Building command-line tools with entry points
• Publishing packages to PyPI or private repositories
• Setting up Python project structure
• Creating installable packages with dependencies
• Building wheels and source distributions
• Versioning and releasing Python packages
• Creating namespace packages
• Implementing package metadata and classifiers

Core Concepts

1. Package Structure

• Source layout: src/package_name/ (recommended)
• Flat layout: package_name/ (simpler but less flexible)
• Package metadata: pyproject.toml, setup.py, or setup.cfg
• Distribution formats: wheel (.whl) and source distribution (.tar.gz)

2. Modern Packaging Standards

• PEP 517/518: Build system requirements
• PEP 621: Metadata in pyproject.toml
• PEP 660: Editable installs
• pyproject.toml: Single source of configuration

3. Build Backends

• setuptools: Traditional, widely used
• hatchling: Modern, opinionated
• flit: Lightweight, for pure Python
• poetry: Dependency management + packaging

4. Distribution

• PyPI: Python Package Index (public)
• TestPyPI: Testing before production
• Private repositories: JFrog, AWS CodeArtifact, etc.

Quick Start

Minimal Package Structure

my-package/
├── pyproject.toml
├── README.md
├── LICENSE
├── src/
│   └── my_package/
│       ├── __init__.py
│       └── module.py
└── tests/
    └── test_module.py

Minimal pyproject.toml

[build-system]
requires = ["setuptools>=61.0"]
build-backend = "setuptools.build_meta"

[project]
name = "my-package"
version = "0.1.0"
description = "A short description"
authors = [{name = "Your Name", email = "[email protected]"}]
readme = "README.md"
requires-python = ">=3.8"
dependencies = [
    "requests>=2.28.0",
]

[project.optional-dependencies]
dev = [
    "pytest>=7.0",
    "black>=22.0",
]