[Python-Dev] dict and required hashing

[Victor Stinner]

Does it mean that depending of the number of items, keys can be mutable? It
sounds like a terrible idea.

Victor

Le vendredi 18 avril 2014, Jim J. Jewett <jimjjewett at gmail.com> a écrit :

> (1)  I believe the recent consensus was that the number of comparisons
> made in a dict lookup is an implementation detail.  (Please correct me
> if I am wrong.)
>
> (2)  Is "the item will be hashed at least once" a language guarantee?
>
> For small mappings, it might well be more efficient to just store the
> 2-3 key/value pairs and skip the bucket calculation.
>
> On the other hand, if a key is not hashable, discovering that long
> after it has already been added to the dict is suboptimal.
>
> Of course, that sort of delayed exception can already happen if it is
> the __eq__ method that is messed up ...
>
> -jJ
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