[Python-Dev] draft pep: backwards compatibility

Paul Moore p.f.moore at gmail.com
Fri Jun 19 10:29:23 CEST 2009

2009/6/19 Benjamin Peterson <benjamin at python.org>:
> Backwards compatibility seems to be an issue that arises a lot here. I
> think we all have an idea of it is, but we need some hard place to
> point to. So here's my attempt:

Nice :-)

A general point - it's probably worth clarifying that you're referring
to major releases (2.6 -> 2.7 etc.) here. Minor releases have a strict
bugfixes-only policy.

> applications and libraries.  This is fantastic; it is probably one of a language
> designer's most wishful dreams.

That's a slightly odd wording. I'm not sure I can think of a better
one, though...

> This policy applys to all public APIs.  These include the C-API, the standard

... applies ...

> * The behavior of an API *must* not change between any two consecutive releases.

With the exception of compatibility warnings as described below.

In practice, I think APIs *do* change, so presumably there must have
been a pair of releases between which the change happened. I see what
you're trying to say, but I think you overstated things a little.


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