[Python-Dev] Proposal: defaultdict

[Phillip J. Eby]

At 10:10 AM 02/17/2006 +0100, Georg Brandl wrote:
>Guido van Rossum wrote:
>
> >   d = DefaultDict([])
> >
> > can be written as simply
> >
> >   d[key].append(value)
>
> > Feedback?
>
>Probably a good idea, has been proposed multiple times on clpy.
>One good thing would be to be able to specify either a default value
>or a factory function.

+1 on factory function, e.g. "DefaultDict(list)".  A default value isn't 
very useful, because for immutable defaults, setdefault() works well 
enough.  If what you want is a copy of some starting object, you can always 
do something like DefaultDict({1:2,3:4}.copy).