Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!uunet!microsoft!jimad
From: jimad@microsoft.UUCP (Jim ADCOCK)
Newsgroups: comp.lang.c++
Subject: Re: asking an object for its type
Message-ID: <71509@microsoft.UUCP>
Date: 25 Mar 91 19:18:24 GMT
References: <71034@microsoft.UUCP> <27D572F6.2A70@tct.uucp> <71199@microsoft.UUCP> <27E1825C.731F@tct.uucp>
Reply-To: jimad@microsoft.UUCP (Jim ADCOCK)
Organization: Microsoft Corp., Redmond WA
Lines: 15


In article <27E1825C.731F@tct.uucp> chip@tct.uucp (Chip Salzenberg) writes:
|>I use "protocol" to mean that an object has to support a *set* of methods
|>correctly matching both in signature and meaning.  Thus, I think your call
|>for an "isKindOf" test is the same requirement as I'm calling for.
|
|Apparently.  The key thing is that two classes can have identical
|lists of public member functions, yet be unrelated.  So if you find
|that your "protocol" matches up, that still proves nothing about the
|ancestry of the object; so that information is useless.

I would consider that two sets of methods matching in signature but not
derived from the same parent are not matching in "meaning".  Thus my concept
of "protocol matching" implies that the methods found in the two matching
protocols derive from a common parent, thus implying ancestry.