Delivered-To: garrigue at math.nagoya-u.ac.jp
Delivered-To: lablgtk at yquem.inria.fr
Date: Tue, 2 Dec 2008 13:40:33 +1100
From: Erik de Castro Lopo <mle+ocaml at mega-nerd.com>
To: lablgtk at yquem.inria.fr
Subject: Re: [Lablgtk] Gdk.cursor / Gtk.Window type error
Message-Id: <20081202134033.a10d0566.mle+ocaml at mega-nerd.com>
In-Reply-To: <20081202.111833.33962760.garrigue at math.nagoya-u.ac.jp>
References: <20081202115407.abc82b31.mle+ocaml at mega-nerd.com>
	<20081202.111833.33962760.garrigue@math.nagoya-u.ac.jp>
Organization: Erik Conspiracy Secret Labs
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Reply-To: lablgtk at yquem.inria.fr

Jacques GARRIGUE wrote:

> You just forgot the parentheses around (win:Gdk.window)
> Without them, this does not specify the type of win, but the return
> type of the function. Hence the error.

I think the lack of parentheses was actually a debugging artifact.
When I add them I get a function with a signature of:

    val create_null_cursor : Gdk.window -> Gdk.cursor

but then I run into trouble when I tried use it. If I replaced this
working code:

    let cursor = Gdk.Cursor.create `PLUS in
    Gdk.Window.set_cursor win#misc#window cursor ;

with:

    let cursor = create_null_cursor win in
    Gdk.Window.set_cursor win#misc#window cursor ;

I got the following error:

    This expression has type GWindow.window but is here used with type
      Gdk.window = [ `drawable | `gdkwindow ] Gobject.obj

Changing the above to this:

    let cursor = create_null_cursor win#misc#window in
    Gdk.Window.set_cursor win#misc#window cursor ;

solved the problem. The fact that I don't use Ocaml's object system
very often made this one a little difficult for me to debug.

Thanks for your help Jacques.

Cheers,
Erik
-- 
-----------------------------------------------------------------
Erik de Castro Lopo
-----------------------------------------------------------------
"Microsoft treats security vulnerabilities as public relations
problems."  -- Bruce Schneier

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