[Python-Dev] Hashable memoryviews

Nick Coghlan ncoghlan at gmail.com
Sun Nov 13 11:54:22 CET 2011

On Sun, Nov 13, 2011 at 8:39 PM, Stefan Krah <stefan at bytereef.org> wrote:
> Antoine Pitrou <solipsis at pitrou.net> wrote:
>> Only if the original object is itself mutable, otherwise the memoryview
>> is read-only.
>> I would propose the following algorithm:
>> 1) try to calculate the original object's hash; if it fails, consider
>>    the memoryview unhashable (the buffer is probably mutable)
> With slices or the new casts (See: http://bugs.python.org/issue5231,
> implemented in http://hg.python.org/features/pep-3118#memoryview ),
> it is possible to have different hashes for equal objects:

Note that Antoine isn't suggesting that the underlying hash be *used*
as the memoryview's hash (that would be calculated according to the
same rules as the equality comparison). Instead, the ability to hash
the underlying object would just gate whether or not you could hash
the memoryview at all.


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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