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[Caml-list] NULL as a caml value
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Lauri Alanko
-
Jacques Garrigue
-
Christopher Quinn
- Jacques Garrigue
- Lauri Alanko
-
Christopher Quinn
-
Jacques Garrigue
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Date: | 2002-05-13 (10:57) |
From: | Jacques Garrigue <garrigue@k...> |
Subject: | Re: [Caml-list] NULL as a caml value |
From: Christopher Quinn <cq@htec.demon.co.uk> > > Yes, NULL is valid, as are all word-aligned addresses outside of the > > Caml heap. > > Does it even need to be word aligned? > If Is_long() tests positive the 'pointer' is also ignored. > I hope I have not erred!? Sure, then this is only an integer, and the GC does not follow integers. Someone even suggested that you can avoid the strange scenario I described in my previous mail by "marking" pointers, that is or-ing them with 1. If they are word aligned, then you can easily recover the original. Otherwise, looking at the runtime's source, I see nothing that would prevent from using any (even non-aligned) pointer outside of the caml heaps to be cast to a value, but the manual does not allow it explicitly, so this may mean that such non-aligned even values could be used for something else. (Actually they are already used for compaction.) Jacques ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners