Hi I am trying to understand something about how the 'in' operator (as in the following expression)
if 'aa' in x: do_something() When trying to implement in support on a class it appears that if __contains__ doesn't exist in falls back to calling __getitem__ However strange things happen to the name passed to __getitem__ in the following example (and in fact in all varients I have triend the name/ key passed to __getitem__ is always the integer 0 For instance Python 2.6.2 (release26-maint, Apr 19 2009, 01:56:41) [GCC 4.3.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> class xx(object): ... def __getitem__(self,name): ... raise KeyError(name) ... >>> aa = xx() >>> aa['kk'] Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 3, in __getitem__ KeyError: 'kk' >>> 'kk' in aa Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 3, in __getitem__ KeyError: 0 I am running on ubuntu, and this happens to 2.5.4 as well. I must say I am surprised and am at a loss as to what is actually going on. Can anyone enlighten me (or should I go and read some 'c' code ;-) Rgds Tim -- http://mail.python.org/mailman/listinfo/python-list
