[Python-Dev] Python-3000 upgrade path

[Neal Norwitz]

On 2/25/07, Thomas Wouters <thomas at python.org> wrote:
>
> It's about how we get Python 2.x to 3.0, and howmuch of 3.0 we put into 2.6 and later.

I've also talked to a bunch of people at PyCon, including Thomas.
There seems to be much concern (rightfully so!) about the upgrade path
from 2.x to 3.x.  I don't think it will be easy to navigate, but I
have confidence we can do a great job.

My goal is to rip out as much cruft from the code base for 3k to make
it easier to maintain.  In order for users to adopt 3k, it must
provide real benefit.  In addition, it as painless as possible for
third party developers to support both 2.x and 3.x.  All the
developers I talked to expressed relief that we weren't forgetting
about them.  There's still unease and will be until we demonstrate
what we plan to do.  They were satisfied with our general approach.

The time schedules in PEP 361 (2.6 release schedule) and what Guido
has said for 3k (from what I remember) are roughly:

  April 2007 - 3.0 PEPs and features accepted/decided
 June 2007 - 3.0a1 - basic (most) features implemented
 Dec 2007 - 2.6a1
 Apr 2008 - 2.6 final
 July 2008 - 3.0 final

Even if we slip these schedules, as long as we keep them in relative
order, we can keep 2.6 robust, while also offering many of the 3k
features.

n