From mboxrd@z Thu Jan  1 00:00:00 1970
Received: (from weis@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id TAA03599 for caml-redistribution; Mon, 12 Apr 1999 19:32:36 +0200 (MET DST)
Received: from concorde.inria.fr (concorde.inria.fr [192.93.2.39]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id NAA22250 for <caml-list@pauillac.inria.fr>; Mon, 12 Apr 1999 13:34:14 +0200 (MET DST)
Received: from morgon.inria.fr (morgon.inria.fr [128.93.8.33])
	by concorde.inria.fr (8.8.7/8.8.7) with ESMTP id NAA01811;
	Mon, 12 Apr 1999 13:34:13 +0200 (MET DST)
Received: (from remy@localhost)
	by morgon.inria.fr (8.8.7/8.8.7) id MAA02666;
	Mon, 12 Apr 1999 12:39:05 +0200
Message-ID: <19990412123905.09954@morgon.inria.fr>
Date: Mon, 12 Apr 1999 12:39:05 +0200
From: Didier Remy <Didier.Remy@inria.fr>
To: Markus Mottl <mottl@miss.wu-wien.ac.at>
Cc: OCAML <caml-list@inria.fr>
Subject: Re: creating fresh objects of type 'self
Reply-To: Didier.Remy@inria.fr
References: <19990412103328.05240@morgon.inria.fr> <199904121103.NAA00431@miss.wu-wien.ac.at>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Mailer: Mutt 0.85e
In-Reply-To: <199904121103.NAA00431@miss.wu-wien.ac.at>; from Markus Mottl on Mon, Apr 12, 1999 at 01:03:54PM +0100
Organization: INRIA, BP 105, F-78153 Le Chesnay Cedex
Phone: (33) 1 3963 5317 -- Sec: (33) 1 3963 5570 -- Fax: (33) 1 3963 5684
Web: http://cristal.inria.fr/~remy
Sender: weis

> This works, of course:
> 
>   class parent = object (self : 'self)
>     val mutable children : 'self list = []
>     method add_fresh_object = children <- {<>} :: children
>   end
> 
> But this is not the intended result: now we have added a *copy* of
> the current object, not of its "fresh" state, i.e. the state it was in
> immediately after creation.

You could use an initializer to remember the "fresh" state in an instance
variable (using {< >}), and use a copy of that instance variable
in the method add_fresh_object. 

    class parent = object (self : 'self)
      val mutable fresh = None
      val mutable children : 'self list = []
      method add_fresh_object =
        let Some x = fresh in children <- Oo.copy x :: children
      initializer  fresh <- Some {< >}
    end;;

Anyway, you have apparently found your own solution.

Best regards,

        Didier