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To: caml-list@inria.fr
Subject: Re: [Caml-list] does class polymorphism need to be so complicated?
References: <3F43E250.1040903@socialtools.net>
	<20030821092849B.garrigue@kurims.kyoto-u.ac.jp>
	<3F448015.8090106@socialtools.net>
	<20030821175808V.garrigue@kurims.kyoto-u.ac.jp>
	<3F449301.8050500@socialtools.net>
From: Remi Vanicat <vanicat@labri.u-bordeaux.fr>
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Date: Thu, 21 Aug 2003 13:44:23 +0200
In-Reply-To: <3F449301.8050500@socialtools.net> (Benjamin Geer's message of
 "Thu, 21 Aug 2003 10:38:09 +0100")
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Benjamin Geer <ben@socialtools.net> writes:

> Jacques Garrigue wrote:

>> OK, there's also another way to do it, without inheritance. I just
>> tried not to be confusing.
>> class type printer = object
>>   method virtual print : #printable -> unit
>> end
>> class my_printer () = object (self : #printer)
>>    method print obj = ...
>> end
>> Looks a bit strange at first, but it does the work.
>
> Is there a way to write a class that implements more than one
> interface? I've tried the following, but it produces a syntax error:
>
> class type virtual printer = object
>     method virtual print : #printable -> unit
> end ;;
>
> class type virtual talker = object
>     method virtual talk : #printable -> unit
> end ;;
>
> class my_printer_talker () = object (self : #printer; #talker)
>      method print obj = (* ... *)
>      method talk obj = (* ... *)
> end ;;

well this work :

class my_printer_talker () = object (self : 's)
     constraint 's = #printer
     constraint 's = #talker
     method print obj = (* ... *)
     method talk obj = (* ... *)
end ;;

-- 
Rémi Vanicat
vanicat@labri.u-bordeaux.fr
http://dept-info.labri.u-bordeaux.fr/~vanicat

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