Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!sdd.hp.com!hplabs!hpda!hpcupt1!thomasw
From: thomasw@hpcupt1.cup.hp.com (Thomas Wang)
Newsgroups: comp.lang.c++
Subject: Re: Re: About Lists and things...
Message-ID: <68070005@hpcupt1.cup.hp.com>
Date: 29 Jun 91 01:22:51 GMT
References: <2865E7A8.179A@tct.com>
Organization: Hewlett Packard, Cupertino
Lines: 24


> If you need a Circle interface, design your software so that you always put
> your Circle onto a CircleList.  Only put your Circles onto ShapeLists when
> you're dealing with Shapes.

This restriction may be acceptable to a large class of programmers, but I
still see it as a significant restriction.

It is best when a description of the physical world problem can be translated
directly into object oriented pseudo code.  Consider how real world containers
work:  If I put cookies into a box that can contain everything, I still know
there are cookies inside the box.  They do not suddenly become generic
objects.  Their type information is not lost.

> I agree with Chip 300%.

It's a trade off between type safety, and information loss.

-steve

> | Steve Vinoski  (508)256-0176 x5904       | Internet: vinoski@apollo.hp.com

 -Thomas Wang                                wang@hpdmsjlm.cup.hp.com
              (Everything is an object.)     thomasw@hpcupt1.cup.hp.com