How to store a function pointer in class?

[Gordon McMillan]

Sami Hangaslammi writes:

> Justin Sheehy <dworkin at ccs.neu.edu> wrote in message
> news:vnd66wo1nz2.fsf at betelgeuse.ccs.neu.edu...
> > You could store the function inside a mutable class data member.
> 
> Yeah, I figured this out myself, but it still seems like an
> unneccessary and ugly hack. 

Perhaps if you understood the mechanics, it would not appear 
that way.

 obj.method(args)

becomes (in psuedo code):
  apply(getattr(obj, method), args)

For instance objects, getattr first checks in the instance, then 
in instance.__class__, then a walk of the bases. It finds a 
function object, (unless it's actually on the instance, but that's 
rare). This is, on the fly, transformed into an unbound method, 
which (when it trickles back to the instance) becomes a 
bound method. This can be called (and the "self" parameter is 
safely squirreled away in the binding).

If you want things on the class that _stay_ function objects, 
you'd need some way to distinguish those which _should_ be 
transformed from those that _shouldn't_. No such flag exists, 
and no such hook exists.

People ask for this regularly. But there are those (like 
yourself) who want to be able to get a plain old function, and 
there are those who want "class methods", ie, methods bound 
to the class object, not the instance object.

- Gordon