[Python-Dev] PEP 408 -- Standard library __preview__ package

Eli Bendersky eliben at gmail.com
Sat Jan 28 07:05:53 CET 2012

On Sat, Jan 28, 2012 at 07:41, Stephen J. Turnbull <stephen at xemacs.org> wrote:
> Eli Bendersky writes:
>  > My point is that if our users accept *this*, in the stable stdlib, I
>  > see no reason they won't accept the same happening between __preview__
>  > and a graduated module, when they (hopefully) understand the intention
>  > of __preview__.
> If it doesn't happen with sufficiently high frequency and annoyance
> factors to make attempting to use both the __preview__ and graduated
> versions in the same code base unacceptable to most users, then
> __preview__ is unnecessary, and the PEP should be rejected.

API differences such as changing one method to another (perhaps
repeated over several methods) is unacceptable for stdlib modules. On
the other hand, for a determined user importing from either
__preview__ or the graduated version it's only a matter of a few lines
in a conditional import. IMHO this is much preferable to having the
module either external or in the stdlib, because that imposes another
external dependency.

But I think that the issue of keeping __preview__ in a later release
is just an "implementation detail" of the PEP and shouldn't be seen as
its main decision point.


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