How to wrap a class's methods?

[rbt]

Jeff Shannon wrote:
> You could probably also do this as a factory function, rather than as a 
> class (also untested!):
> 
> def Wrapper(func):
>     def wrapped(self, *args, **kwargs):
>         s, r = func(self, *args, **kwargs)
>         if s != 'OK':
>             raise NotOK((s,r))
>         return r
>     return wrapped
> 
> I believe that this will be semantically almost equivalent, but 
> conceptually slightly simpler.
> 
> Jeff Shannon

This is a nice example. I have used sub-functions (functions within 
functions) recently with some code, but I've wondered how proper it is 
to do this. Is this type of thing frowned upon?