From: chad fowler <chadfowler@...>
Date: 2001-01-02T00:56:30+09:00
Subject: [ruby-talk:8462] design question

In the Java world, I tend to encapsulate Java's
supplied libraries/types by composing things like
collections inside my own domain objects.  So, for
example, to create a collection ("People") or "Person"
objects, I would create a "People" class with a
limited interface that delegated any requests for
members of the list to an internal representation
which I could vary at a later time (like an ArrayList
or something like that).

The problems I'm trying to solve by doing that in Java
are: 1) I don't want to expose an explicit type which
is not under my control as part of an externally
visible interface, 2) I want to be able to vary the
internal representation at any time, 3) I want to take
care of type casting--mine is a colleciton of
"Person"s, not "Object"s 4) I want my intent to be as
clear as possible (users of my classes won't have to
think "What is this array for?").

So, my question is:  What are the recommended
practices in Ruby?  Do folks generally inherit the
supplied Ruby classes or do they try to use delegation
in the same way I've outlined above?  It seems that a
lot of my reasons for using composition/delegation are
somewhat irrelevant in Ruby, but it still feels really
weird to extend an Array to create a domain-specific
list.

Thanks,
Chad

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