changeset: 78830:895e123d9476 user: Stefan Krah date: Sat Sep 01 14:34:45 2012 +0200 files: Doc/library/stdtypes.rst description: Issue #15814: Document planned restrictions for memoryview hashes in 3.3.1. diff -r d6ebd5d28c76 -r 895e123d9476 Doc/library/stdtypes.rst --- a/Doc/library/stdtypes.rst Sat Sep 01 14:27:51 2012 +0200 +++ b/Doc/library/stdtypes.rst Sat Sep 01 14:34:45 2012 +0200 @@ -2376,8 +2376,8 @@ >>> 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 @@ >>> 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: