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From: vaughan@puma.cad.mcc.com (Paul Vaughan)
Newsgroups: comp.lang.c++
Subject: swapping virtual function table pointers
Message-ID: <2438@cadillac.CAD.MCC.COM>
Date: 21 Aug 89 18:20:18 GMT
Sender: news@cadillac.CAD.MCC.COM
Lines: 24


	I occasionally have related classes with identical data and
function members but differing virtual function definitions.  I'd like
to be able to change the behavior of objects of such classes by
changing the virtual function table pointer in the existing objects.
I use g++ 1.35.1 at the moment.  Three questions:

	1) Is this feasible in cfront 2.0 and/or g++?
	2) Is it possible to define in a portable way within the language?
	3) Could anyone share a hack to do this?

	Now for something more complex, assuming I'm not already
totally fouled up.  Suppose I copied a virtual function table for some
class and changed the virtual function table pointer of an instance of
that class to point to the copy.  Now suppose I were to change
individual elements of this copied table in order to dynamically
change the behavior of an object.

	1) Has anybody tried this?
	2) Does it sound feasible?


 Paul Vaughan, MCC CAD Program | ARPA: vaughan@mcc.com | Phone: [512] 338-3639
 Box 200195, Austin, TX 78720  | UUCP: ...!cs.utexas.edu!milano!cadillac!vaughan