[Python-Dev] dict containment annoyance

tomer filiba tomerfiliba at gmail.com
Sat Aug 12 15:42:17 CEST 2006

>>> 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
it's a question of semantics -- i asked whether the object (a list, in this
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
False, rather than an exception.

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

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