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From: FEYNMAN@acs.tamu.edu (Hamilton, Robert Bryan       )
Subject: Re: What is wrong with OO ?
Date: 1997/02/12
Message-ID: <slrn5g1u19.g3mged.FEYNMAN@VMS1.TAMU.EDU>#1/1
X-Deja-AN: 218188457
References: <5dopri$dei@news4.digex.net> <JSA.97Feb11200125@alexandria>
Organization: Texas A&M University OpenVMS cluster
Newsgroups: 
 comp.lang.c++,comp.lang.smalltalk,comp.lang.eiffel,comp.lang.ada,comp.object,comp.software-eng
Date: 1997-02-12T00:00:00+00:00
List-Id: <comp.lang.ada>


On Wed, 12 Feb 1997 01:01:25 GMT, Jon S Anthony <jsa@alexandria> wrote:
>This seems really confused.  How are the _inherited_ classes
>overriding a _parent's_ function?  I suppose you meant subclasses.
>Anyway, you got it backwards.  The point is that if you don't make the
>things virtual, you can't do the overrides (and other attendant
>stuff).  

??? You can override any method in C++, virtual or no.
The difference is that virtual function _must_ be overridden if
you plan to use it.  

The _real_ point is that you have access to a virtual method even if
the object is referenced by a pointer cast to its parent/higher
class. This can be of great advantage to routines taking a reference
to the parent class as an argument.

>So, there is this problem of either making everything
>virtual, and possibly providing misleading, inappropriate or possibly
>simply inefficient aspects, or not and then risking the mentioned
>problems.

This is no problem unless one makes it one through bad practice.
Just don't use virtual functions _unless_ doing so enhances the clarity
of the program!  Otherwise there's no point to it.

Regards, Robert.