[Distutils] PEP 517: Build system API

Matthew Brett matthew.brett at gmail.com
Wed Nov 23 14:41:05 EST 2016


Hi,

On Wed, Nov 23, 2016 at 6:35 AM, Thomas Kluyver <thomas at kluyver.me.uk> wrote:
> I'd like to push PEP 517 forwards again. This PEP specifies a general
> build system interface so that a source tree can specify a tool (such as
> flit), and pip can ask that tool to generate a wheel. This would allow
> us to install from an sdist or a VCS checkout without running a setup.py
> file.
>
> https://www.python.org/dev/peps/pep-0517/
>
> Developments since the last time this was discussed (to my knowledge):
> - It now uses the pyproject.toml file specified in PEP 518, which was
> already accepted. 517 originally specified a JSON file; 518 explains why
> TOML is preferred (basically: comments).
> - I have implemented the proposed build-system API in a pull request for
> Flit; this has been fairly straightforward so far.
> https://github.com/takluyver/flit/pull/77
>
> Questions:
> 1. Editable installs. The PEP currenly specifies a hook to do an
> editable install (like 'pip install -e' or 'setup.py develop') into a
> given prefix. I don't think that specifying a prefix is sufficient to
> cover '--user' installation, which uses a different install scheme,
> especially on Windows and OSX framework builds. We can:
> a. Add an extra parameter 'user' to the hook, to override the prefix and
> do a user install.
> b. Leave it as is, and do not support editable user installation (which
> would make me sad, as I do editable user installs regularly)
> c. Decide that editable installs are too fiddly to standardise, and
> leave it to users to invoke a tool directly to do an editable install.

I think the standard advice nowadays is to do user installs via pip,
so I would vote for some mechanism to do this - option a).

> 2. Dash vs. underscore, bikeshed reloaded! Currently,  the table name
> uses a dash: [build-system], but the key added by PEP 517 uses an
> underscore: build_backend. This seems a bit messy. I propose that we
> change build_backend to build-backend for consistency. Dashes and
> underscores can both be used in a TOML key without needing quoting.

dash seems good to me too,

Cheers,

Matthew


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