Xref: utzoo comp.lang.c++:3047 comp.lang.lisp:1666 comp.lang.misc:2837
Path: utzoo!attcan!utgpu!watmath!watmsg!gjditchfield
From: gjditchfield@watmsg.waterloo.edu (Glen Ditchfield)
Newsgroups: comp.lang.c++,comp.lang.lisp,comp.lang.misc
Subject: Re: C++ vs. Other OOLs
Message-ID: <25399@watmath.waterloo.edu>
Date: 20 Apr 89 13:53:46 GMT
References: <2602@ssc-vax.UUCP> <5947@pdn.paradyne.com> <38836@bbn.COM> <15425@bellcore.bellcore.com>
Sender: daemon@watmath.waterloo.edu
Reply-To: gjditchfield@watmsg.waterloo.edu (Glen Ditchfield)
Organization: U. of Waterloo, Ontario
Lines: 25

In article <15425@bellcore.bellcore.com> sjs@ctt.bellcore.com (Stan Switzer) writes:
>Adding garbage collection to C++, though, probably does more harm than
>good.  I do not see how to square garbage collection with the notion
>of destructors, for instance.  Remember, destructors aren't just for
>memory management: a "window" destructor might "unmap" the window and
>propogate "repaint" messages to previously obscured windows.

I'd square garbage collection and destructors by having the collector
invoke an object's destructor when it reclaims the object's storage.
Perhaps destructors can help the collector out by breaking pointer cycles
and setting pointers in the object's implementation to nil.
   Dr. Stroustrup's "Possible Directions for C++" paper in the 1987 Usenix
C++ Workshop Proceedings distinguishes "primary objects", which should be
garbage-collected, and "secondary objects", which are part of the imple-
mentation of some other object and which can be easily managed by the other
object's constructors and destructor.  This is another way to reduce the
cost of garbage collection.
   The paper mentions Jonathan Shopiro's "counted pointer" classes, which
provide garbage collection for C++.  Unfortunately the reference given is
for a then-unwritten paper.  Is there a better reference or a publically
available implementation?

    Glen Ditchfield  gjditchfield@violet.uwaterloo.ca  Office: DC 2517
Dept. of Computer Science, U of Waterloo, Waterloo, Ontario, Canada, N2L 3G1
	"... and the rest, we will spend foolishly!" -- _Svengali_