From: "Nicolas Cannasse" <warplayer@free.fr>
To: "Pietro Abate" <Pietro.Abate@anu.edu.au>,
"ocaml ml" <caml-list@inria.fr>
Subject: Re: [Caml-list] sharing problem ...
Date: Mon, 26 Jan 2004 12:22:25 +0100 [thread overview]
Message-ID: <006901c3e3fe$ad44ee40$ef01a8c0@warp> (raw)
In-Reply-To: <20040126104345.GA3978@pulp.anu.edu.au>
> Hi all,
> I'm trying to implement a (string * set) hashtbl
> where some element (set) should be shared between different
> objects.
> the main point is that when I clone an object I want to duplicate
> some sets and shared others (sticky sets)
>
> I tried to achieve this result with the method below.
> it use the set_copy to duplicate a set and does nothing when then
> element is marked as "shared".
[...]
>
> how can I efficiently share elements in this kind of structure ?
The main problem is that you're comparing the sets based on a structural
polymorphic equality (compare) while what you want/need is physical
comparison, which is of course faster and is the only way to detect shared
structures. Sadly, there is no : phys_compare : 'a -> 'a -> int in OCaml,
so you might use the following method :
Add an unique integer "id" to your set in a record, that will enable you to
maintain a hashtbl (or set) of shared structures based on integer comparison
between their id's. That's what OCaml is doing inside the compiler.
Regards,
Nicolas Cannasse
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next prev parent reply other threads:[~2004-01-26 11:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-26 10:43 Pietro Abate
2004-01-26 11:22 ` Nicolas Cannasse [this message]
2004-01-26 13:27 ` Damien Doligez
2004-01-26 13:46 ` Pietro Abate
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