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From: rpk@wheaties.ai.mit.edu (Robert Krajewski)
Newsgroups: comp.lang.lisp
Subject: Re: Destructors in Lisp and CLOS
Summary: It would be nice to have the GC help you...
Message-ID: <9862@rice-chex.ai.mit.edu>
Date: 12 Aug 90 20:03:20 GMT
References: <3296@stl.stc.co.uk> <116718@linus.mitre.org>
Reply-To: rpk@rice-chex.ai.mit.edu (Robert Krajewski)
Distribution: comp.lang.lisp,uk.lisp
Organization: MIT Artificial Intelligence Laboratory
Lines: 24

In article <116718@linus.mitre.org> dsr@luke.mitre.org (Douglas S.
Rand) writes:

    Although this [destructors] might be useful this is
    not a goal of CLOS.  Also it is generally antithetical to the view of
    the LISP world.  It is the job of the GC to clean >up allocated unused
    storage.

Yes, but since the one of the breat benefits of Lisp is that you don't
have to write your own garbage collector, it would be nice to extend
it in ways that CLOS can exploit.

For example, an object may hold onto something that is outside the
Lisp universe, like some kind of operating system resource.  There
is no way for the GC to reclaim it, but it *could* ask the object to
do so.

It's pretty clear that this kind of extension can be fraught with
peril (for example, the reclamation method better not store its object
into anything except lexical places that cannot have a lifetime beyond
the execution of the method itself), but it could be useful.
-- 
Robert P. Krajewski
Internet: rpk@ai.mit.edu ; Lotus: robert_krajewski.lotus@crd.dnet.lotus.com