[Python-Dev] dict containment annoyance

[tomer filiba]

>>> a={1:2, 3:4}
>>> [] in a
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: list objects are unhashable
>>>

imo, the expression should just evaluate to False instead of raising an
exception.
it's a question of semantics -- i asked whether the object (a list, in this
case)
is contained in the dict. i didn't ask whether it's hashable or not. if the
object is
unhashable, then surely it's not contained in the dict, therefore the answer
is
False, rather than an exception.

dict.__contains__ should just swallow these exceptions, and return False.


-tomer
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