From: Gary Wright <gwtmp01@...>
Date: 2007-03-02T10:01:06+09:00
Subject: Re: Duck Typing  Hash-Like Objects


On Mar 1, 2007, at 7:38 PM, James Edward Gray II wrote:
> You're still type checking, you're just doing it in a more fragile  
> way.  If you want to type check, use the class, I say.

Yet if I test for (Hash == mystery_obj) that would not
allow someone to pass an RBTree object instead, which I think
is a very reasonable thing to allow and works just fine if
I only use #fetch.

A minimum interface to an indexable collection might be:

   has_key?(key)
   fetch(key)
   store(key, val)

In a quick look it seems like only Hash and RBTree implement
those methods though.




Gary Wright