On 1/25/2011 10:32 AM, Alan Franzoni wrote:
You're right, I forgot about subclass check. But that's really a
placebo, because it statically checks the object's *class* for such
method,
That is exactly the proper check. Instance *methods* are defined on the
class.
> not the actual instance:
Function attributes of instances are not methods. This is especially
true of special methods.
from collections import Sized
class MyObj(object):
pass
mo = MyObj()
mo.__len__ = lambda: 1
print isinstance(mo, Sized)
False
This is correct!
print(len(mo))
TypeError: object of type 'MyObj' has no len()
--
Terry Jan Reedy
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