Python Packaging with pyproject.toml

Zettel#131

zettelkasten
Published

2023-10-12

Though I may still be in the early stages of my programming journey, I had not learned the most modern way of packaging a Python project six months ago when I started doing it. Initially, I used setuptools and a setup.py file.

However, the pyproject.toml file has emerged as a modern way to specify build dependencies and configurations for Python projects. Below is a practical workflow for creating, building, and distributing a Python package using solely pyproject.toml.

Creating a Package

  1. Setup Your Project Directory

    /path/to/your/project/
├── new_project/          # Python package directory.
│   ├── __init__.py       # Makes the directory a package.
│   └── cli.py            # An example module for CLI.
├── tests/                # Directory for tests.
│   └── cli_test.py       # Test module for CLI.
├── pyproject.toml        # Definition of build process of the package.
└── README.md             # README with info about the project.

  2. Define Your Package Configuration

    [project]
name = "new_project"
version = "0.0.0"

[project.scripts]
new_project = "new_project.cli:cli"

Building and Distributing Your Package

  1. Build Your Package

    python -m build

    This command creates a dist/ folder in your project directory, containing the built package files.

  2. Install Your Package Locally (For Testing)

    pip install -e .

  3. Upload Your Package to PyPi

    pip install twine  # If you haven't installed twine already
twine upload dist/*

Managing Dependencies

[project]
dependencies = [
    "rich",
    "click",
]

[project.optional-dependencies]
test = ["pytest"]

Configuring Entry Points

If you’re creating a CLI tool, specify the entry point in the pyproject.toml like so:

[project.scripts]
new_project = "new_project.cli:cli"

Tool Configuration

Configure tools such as black for code formatting and ruff for linting in the pyproject.toml:

[tool.black]
line-length = 100

[tool.ruff]
line-length = 100

[tool.pytest.ini_options]
testpaths = ["tests"]

Starter pyproject.toml Example

Below is a starter pyproject.toml file for quick project setup:

[project]
name = "new_project"
version = "0.0.0"
authors = [{name = "Sébastien De Revière"},]
description = ""
readme = "README.md"
requires-python = ">=3.12"
classifiers = [
    "Programming Language :: Python :: 3",
    "License :: OSI Approved :: Apache Software License",
    "Operating System :: OS Independent",
]
dependencies = [
    "",
]

[project.optional-dependencies]
test = ["pytest"]
lint = [
    "black",
    "ruff",
]
pypi = [
    "twine",
    "wheel",
]
ci = [
    "pytest",
    "black",
    "ruff",
]

[projects.urls]
Homepage = "https://github.com/sderev/new_project"
Documentation = "https://github.com/sderev/new_project"
Repository = "https://github.com/sderev/new_project"
Changelog = "https://github.com/sderev/new_project/releases"
Issues = "https://github.com/sderev/new_project/issues"

[project.scripts]
new_project = "new_project.cli:cli"

[tool.ruff]
line-length = 100

[tool.black]
line-length = 100

[tool.pytest.ini_options]
testpaths = ["tests"]

References