Python method resolution mystery

Question

I can\'t figure out why this program is failing.

#!/usr/bin/env python
from __future__ import division, print_function
from future_builtins import *
import t         


        

Answer 1

This is somewhat similar to the issue someone else has encountered just yesterday. In short, it seems like special methods (like __getattr__, __str__, __repr__, __call__ and so on) aren't overridable in new-style class instance, i.e. you can only define them in its type.

And here's an adaptation of my solution for that problem which should hopefully work for yours:

def _q_getattr(self, attr):
    print("get %s" % attr)
    return getattr(self, 'x')

def override(p, methods):
    oldType = type(p)
    newType = type(oldType.__name__ + "_Override", (oldType,), methods)
    p.__class__ = newType

override(p, { '__getattr__': _q_getattr})
print(p.__getattr__('x')())  # Works!  Prints "0"
print(p.x())                 # Should work!