[Python-Dev] Hashable memoryviews

Antoine Pitrou solipsis at pitrou.net
Sun Nov 13 02:19:27 CET 2011

On Sat, 12 Nov 2011 17:15:08 -0800
Guido van Rossum <guido at python.org> wrote:
> Aren't memoryview objects mutable? I think that the underlying memory
> can change, so it shouldn't be hashable.

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)
2) otherwise, calculate the memoryview's hash with the same algorithm
   as bytes objects (so that it's compatible with equality comparisons)



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