+= return value

[shochet at hotmail.com]

I am confused with the return values of the augmented assignment
opertators. When redefining them in a class, what should they return?
Coming from a C++ background, I assumed returning None (aka void) would
suffice, but it looks like you need to return self (?)

class MyInt:
    def __init__(self,value):
        self.value = value
    def __iadd__(self, other):
        self.value = self.value + other.value
        return None

f = MyInt(1)
g = MyInt(2)
f+=g

f is now None, not a MyInt with a value of 3 as I expected.

So that is fine, returning self in __iadd__ does the trick, but now all
the C++ code I have wrappers for that return void do not work. Does
this appear broken to anybody else? Why do these operators need any
return value? It would seem enough simply to set the object's internal
state.

Even stranger is:
x = 2
x+=1
 ...does not return anything but it works!?


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