What is adding methods to a class instead of "properly" subclassing called?

Question

Take a simple example in python:

>>> class A(object):
...     pass
...
>>> def f(self):
...     print "f called"
...
>>> A.f = f
>>> a = A()
>>> a.f()
f called

So in this example, the already existing class A gets an additional (instance) function f (though overriding existing ones works just as well). In real life this would of course happen e.g. in different modules. But how is this procedure called?

Answer 1

Not sure I am following you, but if I do, you are talking about extension methods