[Python-Dev] collections.idset and collections.iddict?

[Alex Martelli]

On Mar 6, 2006, at 4:43 PM, Bob Ippolito wrote:
>
> On Mar 6, 2006, at 4:14 PM, Guido van Rossum wrote:
    ...
>> I wonder if this use case and the frequently requested
>> case-insensitive dict don't have some kind of generalization in  
>> common
>> -- perhaps a dict that takes a key function a la list.sort()?
>
> +1.  I've wanted such a thing a couple times, and there is some
> precedent in the stdlib (e.g. WeakKeyDictionary would be a lot
> shorter with such a base class).

Seconded -- though at least in the cases I remember better what I  
really needed was a _list_ with such functionality (order was  
significant, but I wanted 'in'-tests and find and remove calls to  
work by id, not by ==) -- I ended up with a somewhat more complicated  
solution (not just a list subclass, though that might perhaps be  
simpler). In the case where I needed a dict, I inherited from  
DictMixin and delegated some methods (with id(key) instead of key) to  
a self.somedict -- if a dict could be built with a key function, the  
solution would be both simpler and faster.


Alex