[issue24434] ItemsView.__contains__ does not mimic dict_items

[Caleb Levy]

Caleb Levy added the comment:

@serhiy.storchaka: I don't think that will work.

First of all,

    x, y = item

will raise a ValueError if fed an iterable whose length is not exactly 2, so you would have to check for that. Moreover, if item is something like a dict, for example, then:

    {"a": 1, "b": 2} in DictLikeMapping(a="b")

could return True, which I don't think would be expected behavior.

I'm not terribly fond of the instance check myself, but in this case I can't see any other way to do it: the built in dict_items necessarily consists of *tuples* of key-value pairs.

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<http://bugs.python.org/issue24434>
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