Usefulness of subclassing builtin number types

[Antonio Cuni]

Gerhard Häring wrote:

> I want 'x' to stay of the class MyInt. I even can't think of any use
> case right now where I'd *not* want this. The problem? Python doesn't
> do this, instead it always returns ints.

what about the following?

def make_wrapper(method_name):
    def wrapper(self, other):
        return MyInt(getattr(int, method_name)(self, other))
    return wrapper

class MetaInt(type):
    methods = ['__add__', '__sub__']
    def __new__(cls, bases, name, dic):
        for method in MetaInt.methods:
            dic[method] = make_wrapper(method)
        return super(MetaInt, cls).__new__(cls, bases, name, dic)

class MyInt(int):
    __metaclass__ = MetaInt

if __name__=='__main__':
    x = MyInt(3)
    y = x + 4
    print y, type(y)

It seems to work, but I didn't test it very much: obviously it can be 
improved, e.g. by giving 'int' and 'MyInt' as parameters instead of 
hard-coded classes.

ciao Anto
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"Computer science is not about computers any more than astronomy
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