Motivation

Since the introduction of PEP 518 and some following PEPs that expands on the idea, the pyproject.toml format has gained a lot of adoption and became the de facto format for python packages.

However, a more popular option, and the current default format in nixpkgs is setuptools. Luckily, we might still be able to build these packages with format = "pyproject" because pyproject.toml falls back to using setuptools as its build backend as documented by pypa even if the package doesn't have a pyproject.toml. This might actually be preferred, because I ran into issues with format = "setuptools" when trying to package a setup.py package.

Proposal

I am proposing to deprecate the format option and replacing it with a pyproject option for packages that don't work with pyproject. We can do this over a longer period of time:

1. introduce a pyproject option that conflicts with the existing format option, where true is equivalent to format = "pyproject" and false is equivalent to format = "other"
   • python310Packages.buildPythonPackage: introduce pyproject option #254136
2. enforce newly added python packages to use the pyproject option instead of format
   • python310Packages.buildPythonPackage: introduce pyproject option #254136
3. convert existing format = "setuptools" and format = "pyproject" to pyproject = true and the rest to pyproject = false
4. deprecate format with a warning and make the default behavior pyproject = true (instead of format = "setuptools")
5. remove all pyproject = trues, as this is now the default
6. remove the format option altogether

Related Issues

• Python: remove format = "setuptools"; as default #124051
• pyproject build requires build-system definition nix-community/nix-init#119