PEP 621: Migrate from setup.py to pyproject.toml

[cclauss]

How

Migrate setup.py to setup.cfg using setuptools-py2cfg plus manual modifications. Use setup-cfg-fmt to format the results.

Migrate settings from setup.cfg into pyproject.toml using ini2toml to do the file conversion and running pyproject-fmt and then validate-pyproject to validate the results.

Why

https://setuptools.pypa.io/en/latest/userguide/quickstart.html#basic-use

We recommend users expose as much as possible configuration in a more declarative way via the pyproject.toml or setup.cfg, and keep the setup.py minimal with only the dynamic parts (or even omit it completely if applicable).

From validate-pyproject README:

With the approval of PEP 517 and PEP 518, the Python community shifted towards a strong focus on standardization for packaging software, which allows more freedom when choosing tools during development and make sure packages created using different technologies can interoperate without the need for custom installation procedures.

This shift became even more clear when PEP 621 was also approved, as a standardized way of specifying project metadata and dependencies.

validate-pyproject was born in this context, with the mission of validating pyproject.toml files, and making sure they are compliant with the standards and PEPs.

[nicholasserra]

@frankwiles Ill let you take a peek at this one as you're likely using the setup.py to push to pypi. This is the first i've seen of this new config stuff.