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Issue #15814: Document planned restrictions for memoryview hashes in 3.3.1.

This commit is contained in:
Stefan Krah 2012-09-01 14:34:45 +02:00
parent 2a70535afd
commit 9ecae7a437
1 changed files with 7 additions and 15 deletions
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Doc/library/stdtypes.rst
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@ -2376,8 +2376,8 @@ copying.
>>> data
bytearray(b'z1spam')
Memoryviews of hashable (read-only) types are also hashable. The hash
is defined as ``hash(m) == hash(m.tobytes())``::
Memoryviews of hashable (read-only) types with formats 'B', 'b' or 'c'
are also hashable. The hash is defined as ``hash(m) == hash(m.tobytes())``::
>>> v = memoryview(b'abcefg')
>>> hash(v) == hash(b'abcefg')
@ -2387,21 +2387,13 @@ copying.
>>> hash(v[::-2]) == hash(b'abcefg'[::-2])
True
Hashing of multi-dimensional objects is supported::
>>> buf = bytes(list(range(12)))
>>> x = memoryview(buf)
>>> y = x.cast('B', shape=[2,2,3])
>>> x.tolist()
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
>>> y.tolist()
[[[0, 1, 2], [3, 4, 5]], [[6, 7, 8], [9, 10, 11]]]
>>> hash(x) == hash(y) == hash(y.tobytes())
True
.. versionchanged:: 3.3
Memoryview objects are now hashable.
Memoryview objects with formats 'B', 'b' or 'c' are now hashable.
.. note::
Hashing of memoryviews with formats other than 'B', 'b' or 'c' is
possible in version 3.3.0, but will raise an error in 3.3.1 in order
to be compatible with the new memoryview equality definition.
:class:`memoryview` has several methods: