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Newbie inheritance problem

Oleg Broytmannphd at phd.fep.ru
Mon Apr 2 09:06:07 EDT 2001


On Mon, 2 Apr 2001, zzzzz wrote:> Hi all, I have overwridden the __add__ method for a class, then built> a class based on the above class; however, the object I'm returning is> of the base class not the inherited class. If that doesn't make sense> see below:>> class A:>     def __init__(self,value=0.0)>         self._value=float(value)>     def __add__(self,other)>         return A(self._value+other._value)>> class B(A):>     pass>> x=B(3)> y=B(2)> z=x+y>> The way I've done it z becomes an instance of A not B!!! How do I do> it correctly? Do I have to override all the __add__, __sub__, etc...> methods?    def __add__(self,other)        return self.__class__(self._value+other._value)Oleg.----     Oleg Broytmannhttp://phd.pp.ru/phd at phd.pp.ru           Programmers don't die, they just GOSUB without RETURN.


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