Small problem when overloading member functions...

[Sean]

I'm a little new to the language, so please excuse me if I'm missing
something obvious.  I've run into (what looks like) a strange
inconsistency in the language.  Anyway, I have a setup where I
initialize a class object within another class, and then have to
overload one of the new object's functions:

BEGIN SAMPLE CODE:

class A:
  def __init__(self):
    pass
    
  def setFunction(self, fromFunc, toFunc):
    fromFunc = toFunc
    
  def myPrint(self):
    print 'Old'  


class myClass:
  def __init__(self):
    a = A()

    #a.setFunction(a.myPrint, self.newPrint)
    a.myPrint = self.newPrint

    a.myPrint()

  def newPrint(self):
    print 'New'


b = myClass()


END SAMPLE CODE

The code above works fine, and prints out 'New' like it should. 
However, when I try to use the commented line (a.setFunction...)
instead of (a.myPrint = self.newPrint), the a.myPrint function is not
getting overloaded and still prints out 'Old'.  It seems to me that
since I'm passing both method instance objects to a.setFunction(),
there should be no problem overloading them.  Is there a way I can do
this with a function call?  It's important for this system to have a
generic method for overloading functions...