operator overloading

[7stud]

On Apr 4, 12:41 pm, "7stud" <bbxx789_0... at yahoo.com> wrote:
> On Apr 4, 3:36 am, "looping" <kad... at gmail.com> wrote:
>
>
>
> > Hi,
> > for the fun I try operator overloading experiences and I didn't
> > exactly understand how it works.
>
> > Here is my try:>>> class myint(int):
>
> >         def __pow__(self, value):
> >                 return self.__add__(value)
>
> > >>> a = myint(3)
> > >>> a ** 3
>
> > 6
>
> > OK, it works. Now I try different way to achieve the same result but
> > without much luck:
>
> > >>> class myint(int):
> >         pass
> > >>> myint.__pow__ = myint.__add__
>
> > or:>>> class myint(int):
>
> >         __pow__ = int.__add__
>
> > or:
>
> > >>> class myint(int):
> >         pass
> > >>> a.__pow__ = a.__add__
>
> > but for every try the result was the same:>>> a = myint(3)
> > >>> a ** 3
>
> > 27
>
> > Why it doesn't works ?
>
> Look at the output of the following code:
>
> class myint(int):
>     pass
>
> print myint.__pow__
> print myint.__add__
>
> -----output:-----
> <slot wrapper '__pow__' of 'int' objects>
> <slot wrapper '__add__' of 'int' objects>
>
> That shows that the names '__pow__' and '__add__' are __slots__.
> According to Python in a Nutshell(p.102), a name that is a slot can
> only be "bound"(i.e. assigned to) inside the class body.  Any later
> attempt to assign something to a name that is a slot has no effect.
> In your case, I think that means that the only place you can assign
> something to an int slot is inside the int class.
>
> As an alternative, you could override __pow__(). Something like this:
>
> class myint(int):
>     def __pow__(self, num):
>         return super(myint, self).__add__(num)
>
> n = myint(3)
> print n**3
>
> ---output:---
> 6
>
> That doesn't attempt to reassign something to the slot int.__pow__;
> rather it creates a new __pow__ name that hides int.__pow__.

Hmmm...after reading Ziga's post and doing some more testing, I don't
think __slots__ has anything to do with it.