[Python-ideas] working on a PEP for the __preview__ package

Nick Coghlan ncoghlan at gmail.com
Wed Jan 4 13:20:17 CET 2012

On Wed, Jan 4, 2012 at 10:03 PM, Jakob Bowyer <jkbbwr at gmail.com> wrote:
> Surely preview should only contain whats being previewed for the next
> release then when its released with the next version they carry deprecation
> warnings and are removed in the following version e.g.
> v1
> __preview__.magic
> v2
> deprecate(__preview__.magic)
> v3
> There is no longer __preview__.magic in __preview__

The expected progression is:

There is no longer a __preview__.example (What's New will say whether
to find it in the standard library or on PyPI)

I think there's a useful set of guidelines to come out of this
discussion, though:

1. All __preview__ candidates must be available as supported modules on PyPI
2. Entry into __preview__ marks the start of the transition to the
standard library. Issues may be reported both via project specific
channels and core Python channels.
3. If insurmountable problems are encountered during the preview
release (for example, buildbot instability on par with that
historically exhibited by bsddb), the project will be removed from
__preview__ and revert to standalone status
4. If no such problems are encountered, the module fully enters the
standard library in the subsequent release, with the PyPI release
remaining available for use in earlier Python versions

So multi-version code (such as other packages published on PyPI)
should generally depend on the PyPI version, but __preview__ becomes
an option if you can't use the PyPI version for some reason.


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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