[Python-Dev] Proposed 3.0 compatiblity module

[Phillip J. Eby]

At 03:18 PM 1/16/2007 -0800, Guido van Rossum wrote:
>On 1/16/07, Phillip J. Eby <pje at telecommunity.com> wrote:
> > The idea here being that, once 2.6 is widely-enough deployed that it can be
> > assumed as a base for one's users, you can simply run the translator once,
> > do any cleanup, and then have 3.0-clean code that also still runs for your
> > installed base.
> >
> > That way, there's no chasm to leap; just a code cleanup.
>
>I understand; I would rather have that too, everything else being the
>same. But everything else wouldn't be the same -- it would place many
>more restrictions on 3.0, and the common subset would still be much
>smaller. For me personally, the weight of the added restrictions to
>3.0 is the killer.

I don't understand; how would adding features to 2.6 restrict what you 
could add to 3.0?