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Package requirements and guidelines

The guidelines on this page provide minimum requirements for Scikit-HEP packages, which we hope help providing high-quality packages with some level of homogeneity across them. New packages should adhere to these minimum requirements. Further optional suggestions and assistance are provided in the following pages.

Package license (required)

Every package is required to have a license. As a guideline, we try to be as open as possible with licensing, following what most of the other packages use in the wide Python scientific community; Scikit-HEP packages typically use the BSD-3 license. It is acknowledged that exceptions are needed and “sticky licenses” such as GPL may be the only viable option.

README (required)

A README.[md,rst] file is required. It should provide an overview of the package and at least a quick getting started section. There are several examples on how to go about this in the various Scikit-HEP packages.

Documentation (required)

Documentation in the code is a must and docstrings should permeate the code as much as possible. It is suggested to also provide documentation via ReadTheDocs.

Code formatting (optional)

We highly recommend but do not require Black, which is supported by the Python Software Foundation and provides a consistent style across many different packages. For special cases, you can disable formatting for that line/section only. It is also recommended that you use pre-commit to control these checks with a standard interface. See Style for details.

Tests and continuous integration (required)

A reasonable test suite is a requirement, and it is desirable to achieve high coverage. We require at least some tests, with pytest being our recommended framework. You should run your tests in CI; see our GitHub Actions (GHA) page for a simple introduction to setting up CI.

Packaging (required)

You must have a pyproject.toml, and if you use setuptools, a setup.cfg and/or a setup.py. You should have basic information filled out about your project. A minimal pyproject.toml for setuptools is:

[build-system]
requires = ["setuptools", "wheel"]
build-backend = "setuptools.build_meta"

This will enable build isolation, consistent build environments, and will keep build tools from triggering setuptools.build_meta:__legacy__, which is probably not what you want.

You must have a python_requires (or equivalent for non-setuptools builds). You must always test the lowest item in your python_requires; if you drop a version, change your python_requires before release.

Wheels (required)

Except in special circumstances, you must provide SDists and wheels on PyPI. This also means your package must be “installable”, and therefore should be using a PEP 517 compliant packaging framework. Since many Scikit-HEP packages have a binary component, we recommend setuptools. It is highly recommended you automate the building and uploading process so that other Scikit-HEP admins can make emergency (patch) releases if the need arises; non-standard/non-trivial processes should be avoided and documented if unavoidable.

If you have a pure Python package, pip install build; python -m build will build your package’s SDist and wheel using the specified PEP 517 backend in pyproject.toml.