Path: utzoo!attcan!ncrcan!scocan!jfischer
From: jfischer@sco.COM (Jonathan Fischer)
Newsgroups: comp.lang.c++
Subject: Re: polymorfism on objects, not pointers
Summary: Fixed in 2.1
Keywords: polymorfism dynamic binding
Message-ID: <1990Jul6.151916.3993@sco.COM>
Date: 6 Jul 90 19:19:16 GMT
References: <631@atcmpe.atcmp.nl>
Reply-To: jfischer@sco.COM (Jonathan Fischer)
Organization: SCO Canada, Inc. (formerly HCR Corporation)
Lines: 31

leo@atcmp.nl (Leo  Willems) writes:

>In the example below ::g() accepts a class B variable (not a pointer/reference)
>If g() is called with a D (derived from B) the virtual mechanism works!

>	B bb;
>	D dd;

>	g(dd);		//see end of posting for complete code

>In C++ 1.2 this didn't work (compile time error: can not make a B from a D)
>but in 2.0 it is possible to make a B from a D but as I understand it that
>should not alter the B behaviour, and so no runtime binding is expected.
>[etc.]


	The behaviour has changed in cfront 2.1; namely, with the following
calls,
	g(bb);
	g(dd);
the output is
	fb()
	fb().

	When the parameter is a reference or a pointer, however, the
appropriate virtual function is called.
-- 
Jonathan Fischer	     SCO Canada, Inc.	    Toronto, Ontario, Canada

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