[Distutils] PEP470, backward compat is a ...

[Paul Moore]

On 16 May 2014 18:10, Donald Stufft <donald at stufft.io> wrote:
> We can have a singular
> clear message that says "If you want to do X then use these flags" and it
> doesn't matter what version you're on. I vastly prefer that to the current
> situation (and the "just let the deprecation run it's course" proposal) where
> you have to pick the right combination of flags based on pip version.

I see the deprecation proposal as more a case of going straight for
the clear "use these flags" message, but holding off on breaking
people's code immediately, and rather saying "if you're still using
any of the old mess, we plan on removing it following the normal
deprecation process, but we recommend changing now, as the better
mechanisms are already available and are backward compatible"

Or, to put it another way, using --extra-index-url/--find-links is an
available solution *right now*. We can immediately switch to promoting
that both to end users and to package authors.

PEP 370 then becomes simply the means of deprecating and removing all
the old functionality, and clarifying the way that package maintainers
should support the alternative (I won't say "new" as it's been
available forever) extra index approach if they still want to host
externally. Add some bits to describe what should happen with
unmaintained packages[1], and how we propose to offer enhanced
discoverability of extra indexes, and that's it.

Paul

[1] I'm assuming that we don't have any cases where authors of
maintained packages hosted outside of PyPI refuse to set up an index
page. There's no technical reason why they should do so, but there
remains the possibility of non-technical issues that need to be
thrashed out, and consensus reached with the conclusions documented in
the PEP.