Path: utzoo!utgpu!watmath!watdragon!akwright
From: akwright@watdragon.waterloo.edu (Andrew K. Wright)
Newsgroups: comp.lang.c++
Subject: Re: OOP languages and software reuse
Message-ID: <10257@watdragon.waterloo.edu>
Date: 6 Dec 88 13:38:35 GMT
References: <1250001@hpcllca.HP.COM> <612@cadillac.CAD.MCC.COM> <10121@watdragon.waterloo.edu> <1319@cod.NOSC.MIL>
Reply-To: akwright@watdragon.waterloo.edu (Andrew K. Wright)
Organization: U. of Waterloo, Ontario
Lines: 21

In article <1319@cod.NOSC.MIL> owen@cod.nosc.mil.UUCP (Wallace E. Owen) writes:
>In article <10121@watdragon.waterloo.edu> akwright@watdragon.waterloo.edu (Andrew K. Wright) writes:
>>ie.  I have a pre-existing class STRING (built by someone else),
>>which I am not allowed to modify.  Then I cannot sort it, unless
>>the designer anticipated my need and caused STRING to inherit from
>>SORTABLE.
>This problem 'goes away' with multiple inheritance. Derive a class
>SORTABLE_STRING from SORTABLE and STRING.

This problem does *not* go away with multiple inheritance.  The solution
you propose is not acceptable because it requires me to modify existing
code to use SORTABLE_STRING rather than STRING.

Someone else has written a procedure which returns arrays of STRINGs
(perhaps it is in a library).  It is inviolate, you cannot touch it
(perhaps you only have it in binary form, because you bought it from
a software supplier).  Single or multiple inheritance, you have no
way of sorting this array.

Andrew K. Wright      akwright@watmath.waterloo.edu
CS Dept., University of Waterloo, Ont., Canada.