From: Joel VanderWerf <vjoel@...>
Date: 2008-10-16T10:51:15+09:00
Subject: Re: Sample for Metaprogramming

Chad Perrin wrote:
> On Thu, Oct 16, 2008 at 04:53:04AM +0900, Sebastian Hungerecker wrote:
>> Chad Perrin wrote:
>>> I'm aware of the existence of CLOS, but don't really know anything about
>>> its specifics of implementation and use.  How does it handle the kind of
>>> functionality that, in Ruby, consists of sending messages to objects to
>>> invoke their methods?
>> It doesn't, really. CLOS methods are overloadable functions basically, i.e. 
>> you can define multiple methods of the same name, but with different argument 
>> types, and it'll pick the right one to call depending on the type(s) of the 
>> object(s) you pass as arguments. There's no concept of a receiver though.
> 
> So, basically, instead of real methods, CLOS just uses . . . what?
> Parametric polymorphism?  This isn't meant as a challenge or complaint,
> but rather just a question so I'll understand it better:

IIRC: CLOS uses generic functions, aka multimethod dispatch. Think of a 
hash table that maps n-tuples of classes to implementation functions.

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407