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From: dewar@cs.nyu.edu (Robert Dewar)
Subject: Re: Great Circle and Ada?
Date: 1996/09/15
Message-ID: <dewar.842783404@schonberg>#1/1
X-Deja-AN: 180775267
references: <323B1FFD.FA4@syspac.com>
organization: Courant Institute of Mathematical Sciences
newsgroups: comp.lang.ada
Date: 1996-09-15T00:00:00+00:00
List-Id: <comp.lang.ada>


John Volan says

"The "transparent" version of Great Circle is a conservative garbage
collector: It determines which heap-allocated objects are still
accessible,
by searching through memory for any 32-bit value that contains an
address
on the heap. Obviously, this scheme can miss some garbage if a
non-pointer bit-pattern happens to look like a heap address.
"

It can also garbage collect good stuff, there is no requirement that
a pointer to a block exist as such for a block to still be required
to stay around. An obvious counter-example is the use of virtual
origins to reference dynamically allocated arrays.


That's not to say this kind of technology is not useful, just that you
have to be careful to discount any bogus claims that it is bound to
be reliable!