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 ```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 = "you@example.com"}] readme = "README.md" requires-python = ">=3.8" dependencies = [ "requests>=2.28.0", ] [project.optional-dependencies] dev = [ "pytest>=7.0", "black>=22.0", ] ``` ## Package Structure Patterns ### Pattern 1: Source Layout (Recommended) ``` my-package/ ├── pyproject.toml ├── README.md ├── LICENSE ├── .gitignore ├── src/ │ └── my_package/ │ ├── __init__.py │ ├── core.py │ ├── utils.py │ └── py.typed # For type hints ├── tests/ │ ├── __init__.py │ ├── test_core.py │ └── test_utils.py └── docs/ └── index.md ``` **Advantages:** - Prevents accidentally importing from source - Cleaner test imports - Better isolation **pyproject.toml for source layout:** ```toml [tool.setuptools.packages.find] where = ["src"] ``` ### Pattern 2: Flat Layout ``` my-package/ ├── pyproject.toml ├── README.md ├── my_package/ │ ├── __init__.py │ └── module.py └── tests/ └── test_module.py ``` **Simpler but:** - Can import package without installing - Less professional for libraries ### Pattern 3: Multi-Package Project ``` project/ ├── pyproject.toml ├── packages/ │ ├── package-a/ │ │ └── src/ │ │ └── package_a/ │ └── package-b/ │ └── src/ │ └── package_b/ └── tests/ ``` ## Detailed patterns and worked examples Detailed pattern documentation lives in `references/details.md`. Read that file when the navigation tier above is insufficient.