Observer pattern thoughts

[David Eppstein]

In article <20030306154232.7eb31309.gry at ll.mit.edu>,
 george young <gry at ll.mit.edu> wrote:

> Why require an observer to
>   observable.register(self)
> and define a member update(self), when it seems like the observable
> could just take a callable object and call it:

How do you unregister?  You'd need to store the identity of the callable 
somewhere, since (e.g. if it's an object method) you can't simply 
generate it again and get a callable with the same identity.

-- 
David Eppstein                      http://www.ics.uci.edu/~eppstein/
Univ. of California, Irvine, School of Information & Computer Science