[Distutils] build system abstraction PEP

[Marcus Smith]

>
>
> Current draft text in rendered form at:
> https://gist.github.com/rbtcollins/666c12aec869237f7cf7
>
>
Thanks for working on this.
Overall I like the idea, but have some comments/questions


1)  *Please*, *please*, *please* let's start doing PEP conversations as PRs
to pypa/interoperability-peps :  )  There's a place in there for unnumbered
PEPs.  Review will be better and faster IMO as PRs.  If the PR gets too
cluttered with old conversations, just start clean with a new PR.   We can
announce the PRs here, but don't discuss them on the mailing list.   The
same goes for trimming down PEP426 as you mention.   Let's do that as a PR
to pypa/interoperability-peps to the existing document.

2) Ditto on Ralf's concerns about readability.  I only really understood it
after seeing the examples you gave to Ralf (they need to be in the PEP, not
just in response to Ralf).   There's a few places I'd want to alter the
wording, but I likely won't bother, unless it's done as a PR.

3) You refer to "source distribution".  What does that mean exactly in this
PEP?  just the current setuptools notion?

4) Although using a process interface is not necessarily a problem, I don't
agree with your point on why a python interface would be unworkable.
You're assuming that pip would try to import all the build tools (for every
dependency it's processing) in the master process.  An alternative could be
that pip would have it's own tool (that runs as a subprocess in an isolated
env) that knows how to load and work with python build interfaces.   You
could argue that a python api is  an advantage, because build tools aren't
forced to grow a certain cli for pip, they just have to add a shim module
that conforms to the interface.   But my point is not to argue for the
Python API, but for you to remove an argument that from what I can tell,
isn't really an argument for one or the other.

5) at one pt you said "--dump-build-requires would just output a constant
string: {"schema_version": "2.0", "build_requires": []}"   you meant
"metadata_version", right?

6)  Can you explain better why we need to manage a pypa.yaml schema version
*and* a build description schema version.   Why not just a version for
pypa.yaml, and if anything changes (in the yaml schema or the build
"description" api),  then just bump the version.

7) it's unclear when pip get's to run "dist-info" and when the result might
be different.   For example, we've discussed that run time dependencies may
get clarifed *after* the build process.... so this command might produce
different results at different times?

--Marcus



> --
> Robert Collins <rbtcollins at hp.com>
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