En Tue, 29 Jul 2008 13:13:51 -0300, Magnus Schuster
<[EMAIL PROTECTED]> escribi�:
Hello,
I have written the following small proxy class which I expect to pass all
function calls to the 'original' object:
--- BEGIN ---
class proxy(object):
def __init__( self, subject ):
self.__subject = subject
def __getattr__( self, name ):
return getattr( self.__subject, name )
prx_i=proxy(1)
print hasattr(prx_i,'__add__')
j=prx_i.__add__(1)
k=prx_i+1
--- END ---
Actually the "hasattr(prx_i,'__add__')" returns "True" as expected, and
"j=prx_i.__add__(1)" sets j=2.
But "k=prx_i+1" raises a
<type 'exceptions.TypeError'>: unsupported operand type(s) for +: 'proxy'
and 'int'.
How is this addition different from the previous line "j=..."? And how
can I
modify the proxy class so that all methods are passed on, which are not
explicitly overloaded?
__magic__ methods on new style classes are searched in the class, *not* in
the instance. prx_i+1 looks for __add__ in type(prx_i), that is, in the
proxy class. Try implementing a similar __getattr__ method in a metaclass.
--
Gabriel Genellina
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