Seemingly trivial issue calling int's __init__ in python

Question

Observe the following code:

class Angle(int):
    """Basic Angle object: Angle(number)"""

    def __init__(self, angle):
        angle %= 360
        super(Angle, self).__init__(angle)

Fairly simple stuff, Angle is basically just an int that never goes above 360 or below 0. This __init__ just makes sure that the input angle matches the conditions listed prior. But for some reason the above code gives me the following output:

>>> a = Angle(322)
>>> a
322
>>> b = Angle(488)
>>> b
488

Why on earth would this be happening? The code seemed so trivial to me, but maybe I'm just missing something really obvious.

Answer 1

You should be overriding __new__ for immutable classes like int

class Angle(int):
  def __new__(cls, val):
    val %= 360
    inst = super(Angle, cls).__new__(cls, val)
    return inst

see python datamodel for more info