[Python-ideas] Proposal: Moratorium on Python language changes

Guido van Rossum guido at python.org
Wed Oct 21 20:44:16 CEST 2009

On Wed, Oct 21, 2009 at 11:24 AM, Georg Brandl <g.brandl at gmx.net> wrote:
> Well, the moratorium isn't yet in place (which I also gather from you
> posting that on the ideas list), so would be nothing wrong implementing
> something before it starts... :)

No, the moratorium would freeze the language at the version
implemented in 3.1. If necessary we'd have to roll back core language
changes (primarily syntax, or new builtins) made since 3.1 was

> Anyway, I'm not sure how much impact this will have; already there are
> very few real language changes going on; after 2.6, whose such changes
> mostly were Python 3 backports.  In 2.7, the multi-with syntax is the
> only real language change so far.
> (When you say "builtins", do you e.g. include the str.format() mini-language?
> There has been a lot of work on that lately, to fix ambiguous corner-cases.)

I think fixing ambiguous corner cases can proceed.

> I'm not saying it's a bad idea, but while it might stop a few threads on
> python-dev, it won't change a lot in terms of how core development
> time is spent.

My main goal is to set expectations right -- people who spend effort
porting to 3.1 should not be confronted with further effort caused by
the upgrade to 3.2.

(An alternative would be to postpone the release of 3.2 until the
moratorium is over, but this would unnecessarily constrain further
development of the library.)

--Guido van Rossum (home page: http://www.python.org/~guido/)

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