[Python-Dev] frozendict (was: Possible patch for functools partial...)

[Yaniv Aknin]

>
> > So I'm thinking either we make an
> > immutable/hashable dict while we're at it, or store the keyword
> > arguments as a tuple (which guarantees immutability), and only
> > convert them back to a dict when you want to call the partial object
> > (simpler, slower).
>
> I'd support an immutable dict. [...]


I've set out to implement a frozendict (like frozenset) for use to store
functools.keywords' attribute, and quickly realized I didn't think of an
obvious flaw in that idea. A frozenset will only accept hashable members,
but a frozendict can't afford this luxury for its values.

I'm not sure how should I go about handling that, if at all. Should I
implement a frozendict which will remain unhashable but support equality
testing like a regular dict? A frozendict that is only hashable if all its
values are hashable, like a tuple? Is the whole notion of a frozendict
worthy, given this limitation?

I'd be happy to hear python-dev's guidance on this.

Cheers,
 - Yaniv
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