[issue15814] memoryview: equality-hash invariant

[Stefan Krah]

Stefan Krah added the comment:

Martin v. L??wis <report at bugs.python.org> wrote:
> Why be more permissive than necessary? -0 on the committed version;
> it should IMO further restrict it to 1D contiguous byte arrays.

Does "byte arrays" include 'b' and 'c' or just 'B'? I don't see a reason 
to allow 'B' but not the others.


I'm +-0 on allowing multi-dimensional arrays, but it would be
odd to restrict hashing to contiguous arrays:

>>> b = b'abcdefhhijkl'
>>> m = memoryview(b)
>>> b[::-1]
b'lkjihhfedcba'
>>> bytes(m[::-1]) 
b'lkjihhfedcba'
>>> hash(b[::-1]) == hash(m[::-1])
True


My reasoning was: If non-contiguous arrays are allowed (and I think they
should be), why not allow multi-dimensional arrays, too?


The definition hash(m) == hash(m.tobytes()) is pretty straightforward.

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue15814>
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