From: ara.t.howard@...
Date: 2006-07-26T06:35:26+09:00
Subject: Re: I'll have the duck!

On Wed, 26 Jul 2006, Benjohn Barnes wrote:

> *nods* I tend to agree. When I posted earlier, it certainly seemed like the
> person I replied to had "gone beyond" or "gone elsewhere" from what I
> understand by the term "duck typing". As I said, it seemed a lot like
> prototype classes (adding capabilities to something based on the fact that
> it already has certain capabilities). I'd also agree that duck typing is a
> practice; you can do it with c++ templates, for instance, as far as I can
> see.

sortof.  even if you ignore the compile-time vs run-time semantics between
ruby and c-- you still get nailed with 'method_missing' which may well respond
to any message sent:

   harp:~ > cat a.rb
   class BlackBox
     instance_methods.each{|m| undef_method m}
     def method_missing(m, *a, &b) 42 end
   end

   %w( fee fie fum __id__ __send__ ).each{|m| p(BlackBox.new.send(m))}


   harp:~ > ruby a.rb
   42
   42
   42
   42
   42


this is a crucial distinction between any generic programming methodology or
interface paradigm - this is really sending a message to an object which may do
just about anything with it.

regards.

-a
-- 
suffering increases your inner strength.  also, the wishing for suffering
makes the suffering disappear.
- h.h. the 14th dali lama