Date: Sat, 03 May 2003 13:19:52 +0200
Message-ID: <rr8ade46zvr.wl at inria.fr>
From: Jun.Furuse at inria.fr
To: Richard Jones <rich at annexia.org>
Cc: lablgtk at kaba.or.jp
Subject: Re: More GtkHtml questions
In-Reply-To: <20030503100346.GE24136 at redhat.com>
References: <20030503100346.GE24136 at redhat.com>
MIME-Version: 1.0 (generated by SEMI 1.14.3 - "Ushinoya")
Content-Type: text/plain; charset=US-ASCII

Hello,

> Now to define my class:
> 
> class html obj = object
>   inherit GPack.layout (obj : GtkHtml.html obj)
> end
> 
> Except this doesn't actually work. I get:
> 
> File "gHtml.ml", line 40, characters 24-27:
> This expression has type GtkHtml.html Gtk.obj but is here used with type
>   Gtk.layout Gtk.obj
> Type GtkHtml.html = [ `base | `container | `html | `layout | `widget]
> is not compatible with type
>   Gtk.layout = [ `base | `container | `layout | `widget]

This is normal, since layout is defined as a terminal class in gPack.mli:

	class layout :
	  Gtk.layout obj ->
	  object
	    inherit container_full
	    val obj : Gtk.layout obj
	    ...
	end

This means that the argument for new GPack.layout must be 
Gtk.layout obj and nothing else.

If you want to create a new class inherited from layout, I guess
you have to modify the definition of layout class type, so that
it can take an argument whose type is wider than Gtk.layout =
[`base|`container|`layout|`widget]. I think it will be as follows:

	class layout :
	  'a obj ->
	  object
	    inherit container_full
	    constraint 'a = [> Gtk.layout]
	    val obj : 'a obj
	    ...
	end

The class defintion of GContainer.container may be a good example.

# Jacques can  surely give us a better comment than this, 
# but he is in vacation now... Let's wait his return.

--
Jun