From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <micha-1@fantasymail.de>
Delivered-To: caml-list@yquem.inria.fr
Received: from concorde.inria.fr (concorde.inria.fr [192.93.2.39])
	by yquem.inria.fr (Postfix) with ESMTP id C63D7BCAE
	for <caml-list@yquem.inria.fr>; Tue, 28 Jun 2005 14:24:45 +0200 (CEST)
Received: from mxintern.schlund.de (mxintern.kundenserver.de [212.227.126.201])
	by concorde.inria.fr (8.13.0/8.13.0) with ESMTP id j5SCOj5x020490
	for <caml-list@yquem.inria.fr>; Tue, 28 Jun 2005 14:24:45 +0200
Received: from [172.17.36.11] (helo=schluck.use.schlund.de)
	by mxintern.kundenserver.de with esmtp (Exim 4.34)
	id 1DnF8e-0006iE-9b; Tue, 28 Jun 2005 14:24:28 +0200
From: Michael Wohlwend <micha-1@fantasymail.de>
To: caml-list@yquem.inria.fr,
	Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>
Subject: Re: [Caml-list] state pattern...
Date: Tue, 28 Jun 2005 14:24:27 +0200
User-Agent: KMail/1.8
References: <200506262157.02201.micha-1@fantasymail.de> <200506280123.55251.micha-1@fantasymail.de> <20050628.095406.112629429.garrigue@math.nagoya-u.ac.jp>
In-Reply-To: <20050628.095406.112629429.garrigue@math.nagoya-u.ac.jp>
X-Face: S)[vu%Bha1d&ej9GfwAq~7C}A,y[B.uS}+D6'hb~xPwsxymw$fnCOaMe<=?utf-8?q?*bnUajSBR=5Fm=3FR=0A=09?=@V3;iX8[A}z`.%pEQ1r7iZhN8#ktTCBQ}&mkx>=RH&l|l6\]NZI@
MIME-Version: 1.0
Content-Type: text/plain;
  charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
Message-Id: <200506281424.28051.micha-1@fantasymail.de>
X-Virus-Scanned: Symantec AntiVirus Scan Engine
X-Miltered: at concorde with ID 42C1418D.000 by Joe's j-chkmail (http://j-chkmail.ensmp.fr)!
X-Spam: no; 0.00; caml-list:01 'self:01 'self:01 subtype:01 cheers:01 ...:98 ...:98 seems:03 pattern:03 context:04 context:04 problem:05 indeed:05 written:06 implementing:06 
X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on yquem.inria.fr
X-Spam-Status: No, score=0.1 required=5.0 tests=FORGED_RCVD_HELO 
	autolearn=disabled version=3.0.2
X-Spam-Level: 

thanks for your reply, it's increasing my understanding of the object system, 
although there are some (or more... :-) open points:

In:
class ['state] context s =
 object (this:'self)
 ...
end

what are the reasons to give 'this' a type, and isn't 'self a type-variable? I 
thought it ('this') has the type of the class (= _context) ? I don't 
understand why and when it is needed to give the object a type.
The same with:
class state1 = object (this : _ #state) ...  end

I thought class state1 is a subtype (or implementing the class-type) #state, 
since the methods are the same. Why does it help to give the obejct a type?

thanks for your help, I would really like to understand the object system 
better. The state machine is surely better written using records and 
function; but this (supposed to be) little task is/was helping me indeed 
learning more of the class system. (And I hate it, not being able to solve a 
problem, which seems to be an easy one :-)

 cheers
 Michael