[Python-Dev] Python's C interface for types
Giovanni Bajo
rasky at develer.com
Fri Jan 26 20:27:14 CET 2007
On 26/01/2007 17.03, Thomas Wouters wrote:
> How critical is the 'numeric' property of the nb_hash function? I
> can certainly honour it, but is it worth it?
>
> [...]
> There's no strict requirement that
> equal objects must have equal hashes,
Uh? I thought that was the *only* strict requirement of hash. In fact the docs
agree:
====================================================
__hash__( self)
Called for the key object for dictionary operations, and by the built-in
function hash(). Should return a 32-bit integer usable as a hash value for
dictionary operations. The only required property is that objects which
compare equal have the same hash value; [...]
====================================================
I personally consider *very* important that hash(5.0) == hash(5) (and that 5.0
== 5, of course).
--
Giovanni Bajo
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