[Python-Dev] Hashable memoryviews (original) (raw)

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:

try to calculate the original object's hash; if it fails, consider the memoryview unhashable (the buffer is probably mutable)
otherwise, calculate the memoryview's hash with the same algorithm as bytes objects (so that it's compatible with equality comparisons)

Regards

Antoine.