Python Class with integer emulation

Question

Given is the following example:

class Foo(object):
    def __init__(self, value=0):
        self.value=value

    def __int__(self):
        return self.valu         


        

Answer 1

Try to use an up-to-date version of python. Your code works in 2.6.1.

Answer 2

In Python 2.4+ inheriting from int works:

class MyInt(int):pass
f=MyInt(3)
assert f + 5 == 8

Answer 3

You need to override __new__, not __init__:

class Foo(int):
    def __new__(cls, some_argument=None, value=0):
        i = int.__new__(cls, value)
        i._some_argument = some_argument
        return i

    def print_some_argument(self):
        print self._some_argument

Now your class work as expected:

>>> f = Foo(some_argument="I am a customized int", value=10)
>>> f
10
>>> f + 8
18
>>> f * 0.25
2.5
>>> f.print_some_argument()
I am a customized int

More information about overriding new can be found in Unifying types and classes in Python 2.2.