From: michele.simionato@...
Date: 2006-10-06T16:20:10+09:00
Subject: Re: dynamically changing superclass/mixins

Michael Keller wrote:
> 1. Can I change the superclass for an already defined class? That is,
> remove an existing relationship or add a new one? I haven't been able to
> figure that out.
>
> 2. Can I also remove modules that I included into a class? I have only
> found a very ugly way to do this: undefine the class (Klass = nil) and
> define it anew. I am not sure even, what the effect was on existing
> instances; if they adapted the new behaviour or not.

Since people mentioned Io, I feel free to post a Python solution:

class Base(object):
    def meth(self):
        print 'called B.meth'

class Mixin1(object):
    def meth1(self):
        print 'called meth1'

class Mixin2(object):
    def meth2(self):
        print 'called meth2'


class C(Base, Mixin1):
    pass

c = C()

c.meth()
c.meth1()

C.__bases__ = (Base, Mixin2) # change the base classes (ick!)

print [methname for methname in dir(c) if methname.startswith('meth')]

c.meth()
c.meth2()
c.meth1() # this gives an error now


            Michele Simionato