Use pyproject.toml for configuration?

[jrbourbeau]

In #5720 @ian-r-rose and @gjoseph92 brought up switching some (maybe all?) of our various tool configuration (e.g. pytest) from setup.cfg to a pyproject.toml file. Some projects, e.g. pytest, explicitly recommend against using a setup.cfg file in favor of other configuration files like pyproject.toml https://docs.pytest.org/en/6.2.x/customize.html#setup-cfg. I'm not familiar with pyproject.toml so can't speak to various pros and cons -- opening up an issue to see if there's interest in using pyproject.toml

[fjetter]

Disclaimer: I'm not an expert

I have a soft opinion towards moving all config. See below for a bit of research

• Toml docs https://toml.io/en/
• pip docs list a few relevant peps for that config file

https://www.python.org/dev/peps/pep-0518/
https://www.python.org/dev/peps/pep-0517/
https://www.python.org/dev/peps/pep-0621/
https://www.python.org/dev/peps/pep-0660/

• isort lists it as a preferred config format https://pycqa.github.io/isort/docs/configuration/config_files.html
• black supports it https://black.readthedocs.io/en/stable/guides/using_black_with_other_tools.html
• mypy supports it https://mypy.readthedocs.io/en/stable/config_file.html#using-a-pyproject-toml-file

[bryanwweber]

Flake8 does not, and has no plans, to support pyproject.toml: PyCQA/flake8#234 (unfortunately, that thread was migrated from GitLab and is very difficult to follow). Anyhow, Anthony has been very clear that Flake8 has no plans to support pyproject.toml now or in the future 🤷

[ian-r-rose]

I'd be in favor of moving things to a pyproject.toml that support it. It seems to be the preferred format for most (but not all) newer tooling. As a bit of a carrot, it could also help to remove a vendored versioneer and use versioneer-518.

For what it's worth, Anthony is also against it for pre-commit: pre-commit/pre-commit#1165

[fjetter]

For what it's worth, Anthony is also against it for pre-commit: pre-commit/pre-commit#1165

Makes sense. I agree that yaml is a better format for pre-commit.

FWIW, I personally prefer toml and yaml over ini but between toml and yaml this is a tough call and likely application specific. The better file format is also what motivates me more than having all config in one file.