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From: Damien Doligez <damien.doligez@inria.fr>
To: caml-list@inria.fr
Subject: Re: [Caml-list] Hash over ref
Date: Fri, 21 May 2004 00:52:27 +0200	[thread overview]
Message-ID: <5DFDEB16-AAB0-11D8-9E52-00039310CAE8@inria.fr> (raw)
In-Reply-To: <200405202137.00485.jdh30@cam.ac.uk>

On May 20, 2004, at 22:37, Jon Harrop wrote:

> Is it possible to hash a ref itself, rather than the object it 
> references?

If I understand the question correctly, you want the hash to remain
constant even when you update the reference.  Then the answer is no.

The normal technique for this case is to replace your reference with
a record of two fields: a mutable field for the contents, and an int
field which you initialize with a random number (or a sequential
counter) when you create the record.  Then your hash code is this
number.

-- Damien

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  parent reply	other threads:[~2004-05-20 22:52 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-05-20 20:37 Jon Harrop
2004-05-20 20:48 ` David Monniaux
2004-05-20 22:52 ` Damien Doligez [this message]
2004-05-20 23:29 ` Alain Frisch
2004-05-21 10:59   ` Jon Harrop

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