When to use self to reference class itself.

class HideX(object):
    def __init__(self, x):
        self.x = x#   w  ww .j  ava2s  . c o  m

    def get_x(self):
        return ~self.__x

    def set_x(self, x):
        assert isinstance(x, int), '"x" must be an integer!'
        self.__x = ~x

    x = property(get_x, set_x)

inst = HideX(20)
print inst.x
inst.x = 30
print inst.x