From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2009-04-28T16:57:57+09:00
Subject: Re: KaraokeSong#to_s example in book

On Tue, Apr 28, 2009 at 12:40 AM, Clifford Leung <momonariex@gmail.com> wrote:
> I could understand if that was the case, but that's not the case in the
> example in the book.

The point is that if you limit yourself to using the public interface
of a class,
you protect yourself against changes in the internal implementation.

Say that tomorrow, the implementer of the Song class receives a new requirement,
and he decides to store the duration in ms, to more easily implement the new
functionality. Then, if you have used the internal implementation, you
have a problem.

Hope this helps.

Jesus.