[Baypiggies] Assigning functions as class variables

[AM]

Hi.

What I am trying to do is assign a function to a class variable and use 
it. For e.g.:


def foo(a):
     print a

class X(object):

     @classmethod
     def bar(cls, fn):
         cls.fn = fn

     @classmethod
     def baz(cls, a):
         cls.fn(a)


X.bar(foo)
X.baz(12)

If I run this I get:
TypeError: unbound method foo() must be called with X instance as first 
argument (got int instance instead)

I sort of understand why allowing this might cause a bit of trouble as 
fn could be an unbound method which receives X as the first argument, 
however I don't quite understand this particular error.

Changing foo to accept another argument also does not work. If someone 
could enlighten me about:

1. Why exactly is calling the method disallowed in pretty much all forms?

2. How do people work around this?

that would be great.

Thanks.
AM