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From: beard@ux5.lbl.gov (Patrick C Beard)
Newsgroups: comp.std.c++
Subject: Re: type/member tags (was Re: asking an object for its type)
Message-ID: <10721@dog.ee.lbl.gov>
Date: 7 Mar 91 07:47:36 GMT
References: <27C2D973.3C1B@tct.uucp> <DSOUZA.91Feb24173454@optima.cad.mcc.com> <70877@microsoft.UUCP>
Reply-To: beard@ux5 (Patrick C Beard)
Organization: Berkeley Systems, Inc.
Lines: 16
X-Local-Date: Wed, 6 Mar 91 23:47:36 PST


The information about what class an object is can be easily obtained by using
the pointer to the object's virtual function table as the class id, which
whill always be unique for every class.  This could be quite easy to add
to the language and easy to implement.  Class relationships would be easy
to implement by putting a link field in the vtable which points to a
class's super-class.

I agree that using run-time type information is quite easy to abuse, but
then so is multiple-inheritance.  These are powerful tools, but we shouldn't
be forced to live without them.

--
//  Patrick C. Beard, Software Engineer, Berkeley Systems, Inc.
//                    "Heroes of technology."
//   beard@lbl.gov, d0346@applelink.apple.com (ATTN: Patrick)