Support setuptools custom discovery

[zsol]

Some popular projects (e.g. frozenlist being in the top50 on PyPI) use setuptools' custom package discovery mechanism.

[thatch]

Could you provide a little more information about how you're using it, and what is incorrect? I suspect you're reading Distribution.packages and seeing ["find:"] which is what the project gave. If you're interested in the more interpreted version of that value, you probably want Distribution.packages_dict or Distribution.source_mapping. (Note: 0.8.0 doesn't print source_mapping from the cli, but 0.9.0b2 or main does.)

The "version mismatch" problem we've noted internally comes from something similar, being tracked in #4 -- depending on your application for the data, you might want to know that it's being read from a file, and if so which file, or you might just want the numeric result.

Related, dowsing currently doesn't emulate anything related to package_data (because it's complex, easy to get wrong, and it's far safer to just include everything under a top-level dir). See comment at https://github.com/python-packaging/dowsing/blob/main/dowsing/types.py#L113 (and your py.wtf might be the "some people" it refers to).

• dowsing output: https://gist.github.com/thatch/7848927fcd3faf9afbbec43a1869d7a4
• what's in the wheel: https://gist.github.com/thatch/2237636deda81fc405814282e109d289

Future work:

See #70 for an overview of where I'd like to spend my time.

I'm mostly lacking test cases for the IDIC of setuptools-isms. If you have more, please send them my way! I've done a near-full analysis of pypi a couple of years ago focused on buildability from source, and may well do another on dowsing accuracy next chance I have good internet.

I also think it would be interesting to produce a package_dir and top-level mapping for all projects as a static json file you could just grab. I was able to fill in some gaps in static extraction by building in a well-stocked VM that has numpy, cffi, etc preinstalled in my last experiment. My various projects are increasinly interdependent (dowsing started out from a need in opine and checkdeps only knows about already-installed projects).