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From: Francois Rouaix <frouaix@liquidmarket.com>
To: Vyskocil Vladimir <vyskocil@math.unice.fr>
cc: Caml list <caml-list@inria.fr>
Subject: Re: Constante NIL 
In-reply-to: Your message of "Mon, 31 May 1999 16:20:40 +0200."
             <37529AB8.B306AD5F@math.unice.fr> 
Reply-To: frouaix@liquidmarket.com
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Date: Tue, 01 Jun 1999 09:16:55 -0700
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> N'est t'il pas concevable de rajouter a Objectif Caml une constante
> NIL, UNDEF ou je sais pas trop comment la nommer dont la valeur serait
> '_a. Ceci permettrait d'initialiser "par defaut", par exemples,  les
> variables d'instances d'une classe lorsque l'on ne possede aucune
> valeur par defaut du bon type.


In this particular case (dummy initialization value for a CamlTk 
widget), you could use Widget.default_toplevel, or Widget.dummy.
It's inelegant and a bit dangerous, but neither as bad as using
a Widget.widget option type, or as drastic as adding null pointers
in the language.

--f