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authorMartin Panter <vadmium+py@gmail.com>2017-01-29 10:00:23 (GMT)
committerMartin Panter <vadmium+py@gmail.com>2017-01-29 10:00:23 (GMT)
commit8dbb0ca573436dcc780ae3fc00941f928f02b708 (patch)
tree88a4d06c38b923279213bd42e5d7ccca2af555cd
parent3ac504289a93079f2f99d43b51c82153f7b3260a (diff)
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Issue #12067: Recommend that hash and equality be consistent
-rw-r--r--Doc/reference/expressions.rst4
1 files changed, 4 insertions, 0 deletions
diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst
index 9792399..ea89486 100644
--- a/Doc/reference/expressions.rst
+++ b/Doc/reference/expressions.rst
@@ -1255,6 +1255,10 @@ some consistency rules, if possible:
sequences, but not to sets or mappings). See also the
:func:`~functools.total_ordering` decorator.
+* The :func:`hash` result should be consistent with equality.
+ Objects that are equal should either have the same hash value,
+ or be marked as unhashable.
+
Python does not enforce these consistency rules. In fact, the not-a-number
values are an example for not following these rules.