TODO: Reword so it flows better.

The reality of python packaging, even with recent PEPs, is that most nontrivial python packages do moderately interesting stuff in their setup.py:

• Imports (either from local code, or setup_requires)
• Fetching things from the Internet
• Running commands
• Making sure native libs are installed, or there's a working C compiler
• Choosing deps based on platform

The disappointing part of several of these from the perspective of basically running a distro, is that they produce messages intended for humans, rather than actually using the mechanisms that we have in PEP 508 (environment markers) and 518 (pyproject.toml requires).

This project is a bridge to find several things out, about primarily setup.py but also understanding PEP 517/518 as a one-stop-shop, about:

• for cases where the package's version is stored within, but has external requirements that are not listed at build-time, currently returns an unknown value and moves on
• potential imports, to guess at what should have been in the build-time requirements (e.g numpy.distutils is pretty clear)
• doesn't actually execute, so fetches or execs can't cause it to fail
• Gives the PEP 517 APIs get_requirements_for_sdist and get_requirements_for_build_wheel, even on a different platform through simulated execution, with no sandboxing required.
• A lower-level api suitable for making edits to the place where the setup args are defined.

A bunch of this is papering over problems with the current reality. If you have an existing sandbox and are ok with ~30% of projects just failing to build, you can rely on the pep517 module's API to actually execute the code on the current version of python.

If you're willing to run the code and have it take longer, take a look at the pep517 api get_requires_for_* or have it generate the metadata (assuming what you want is in there). An example is in dowsing/_demo_pep517.py

• PEP 241, Metadata 1.0
• PEP 314, Metadata 1.1
• PEP 345, Metadata 1.2
• PEP 566, Metadata 2.1
• https://packaging.python.org/specifications/core-metadata/
• https://setuptools.readthedocs.io/en/latest/setuptools.html#metadata

dowsing is copyright Tim Hatch, and licensed under the MIT license. I am providing code in this repository to you under an open source license. This is my personal repository; the license you receive to my code is from me and not from my employer. See the LICENSE file for details.