[Python-Dev] Edits to Metadata 1.2 to add extras (optional dependencies)

[Eric Snow]

On Wed, Aug 15, 2012 at 8:49 AM, Daniel Holth <dholth at gmail.com> wrote:
> I've drafted some edits to Metadata 1.2 with valuable feedback from
> distutils-sig (special thanks to Erik Bray), which seems to have no
> more comments on the issue after about 6 weeks. Let me know if you
> have an opinion, or if you will have one during some bounded time in
> the future.
>
> Metadata 1.2 (PEP 345), a non-final PEP that has been adopted by
> approximately 10 of the latest sdists from pypy, cannot represent the
> setuptools "extras" (optional dependencies) feature. This is a problem
> because about 1600+ or 10% of the packages hosted on pypy define
> "extras" as measured in May of this year.
>
> The edit implements the extras feature by adding a new condition
> "extra == 'name'" to the Metadata 1.2 environment markers.
> Requirements with this marker are only installed when the named
> optional feature is requested. Valid extras for a package must be
> declared with Provides-Extra: name.
>
> It also adds Setup-Requires-Dist as a way to specify requirements
> needed during an install as opposed to during runtime.
>
>
> Abbreviated highlights:
>
> Setup-Requires-Dist (multiple use)
>
> Like Requires-Dist, but names dependencies needed while the
> distributions's distutils / packaging `setup.py` / `setup.cfg` is run.
>
>
> Provides-Extra (multiple use)
>
> A string containing the name of an optional feature.
>
> Examples:
>
>     Requires-Dist: reportlab; extra == 'pdf'
>
>     Requires-Dist: nose; extra == 'test'
>
>     Requires-Dist: sphinx; extra == 'doc'
>
>
> (full changeset on
> https://bitbucket.org/dholth/python-peps/changeset/537e83bd4068)

s/pypy/PyPI/

-eric