Confusion about __call__ and attribute lookup
eurleif at ecritters.biz
Thu Nov 10 15:34:04 CET 2005
Kent Johnson wrote:
> But why doesn't Foo.__call__ shadow type.__call__? Normally an instance
> attribute takes precedence over a class attribute. Is it something
> special about how function call syntax is handled internally, or do all
> special methods work this way, or is there something else going on?
New-style classes look up special methods on the class, not on the instance:
>>> class Foo(object):
... def __invert__(self):
... return 'foo'
>>> x = Foo()
>>> x.__invert__ = 123
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: 'int' object is not callable
>>> ~x # equivalent to type(x).__invert__()
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