[Python-Dev] Proposal: defaultdict

[Phillip J. Eby]

At 01:44 PM 02/18/2006 -0500, James Y Knight wrote:
>On Feb 18, 2006, at 2:33 AM, Martin v. Löwis wrote:
> > I don't understand. In the rationale of PEP 333, it says
> > "The rationale for requiring a dictionary is to maximize portability
> > between servers. The alternative would be to define some subset of a
> > dictionary's methods as being the standard and portable interface."
> >
> > That rationale is not endangered: if the environment continues to
> > be a dict exactly, servers continue to be guaranteed what precise
> > set of operations is available on the environment.
>
>Yes it is endangered.

So we'll update the spec to say you can't use a dict that has the default 
set.  It's not reasonable to expect that language changes might not require 
updates to a PEP.  Certainly, we don't have to worry about being backward 
compatible when it's only Python 2.5 that's affected by the change.  :)