New submission from Caleb Levy:
The current implementation ItemsView.__contains__ reads
class ItemsView(MappingView, Set):
...
def __contains__(self, item):
key, value = item
try:
v = self._mapping[key]
except KeyError:
return False
else:
return v == value
...
This poses several problems. First, any non-iterable or iterable not having
exactly two elements will raise an error instead of returning false.
Second, an ItemsView object is roughly the same as a set of tuple-pairs hashed
by the first element. Thus, for example,
["a", 1] in d.items()
will return False for any dict d, yet in the current ItemsView implementation,
this is True.
The patch changes behavior to immediately return false for non-tuple items and
tuples not of length 2, avoiding unnecessary exceptions. It also adds tests to
collections which fail under the old behavior and pass with the update.
----------
keywords: +patch
Added file: http://bugs.python.org/file39682/ItemsView_contains.patch
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<http://bugs.python.org/issue24434>
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