From: Olivier Andrieu <andrieu at ijm.jussieu.fr>
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Message-ID: <16054.21660.480451.538290 at akasha.ijm.jussieu.fr>
Date: Mon, 5 May 2003 14:10:04 +0200
To: Richard Jones <rich at annexia.org>
Cc: lablgtk at kaba.or.jp
Subject: Re: More GtkHtml questions
In-Reply-To: <20030505110949.GB10796 at redhat.com>
References: <20030503100346.GE24136 at redhat.com>
	<16051.59001.830936.263287@karryall.dnsalias.org>
	<20030504141338.GA9710@redhat.com>
	<20030505095109.GA10796@redhat.com>
	<16054.16579.173448.942063@akasha.ijm.jussieu.fr>
	<20030505110949.GB10796@redhat.com>

 Richard Jones [Monday 5 May 2003] :
 > > * your wrapping of save functions is not GC-safe, you must register
 > >   your stored closure as a global root. The user_data value is not
 > >   necessary since it can be included in the closure.  So I would do it
 > >   like this :
 > 
 > Yes, I suspected this was not GC-safe.
 > 
 > >   CAMLprim value
 > >   ml_gtk_html_save (value html, value receiver)
 > >   {
 > >     value *closure = ml_global_root_new(receiver);
 > > 
 > >     return Val_bool (gtk_html_save (GtkHTML_val(html),
 > >                                     _save_receiver, closure));
 > >   }
 > 
 > Is it possible to release the global root just after gtk_html_save
 > returns?

Hum, I don't know how gtk_html_save works but I suspect that the
callback is stored somewhere in the object and is referenced after
gtk_html_save returns. If this is indeed the case, the global root
must be kept until the html object is destroyed. 

 > Of course in Caml these are variants, not just integers, so you can't
 > do logical operations on them. I'm not sure if there's an easy way to
 > solve this in Caml - except by having some C native functions for
 > converting font_style to integers and/or performing logical
 > operations.  This doesn't seem type safe to me. Do you have any
 > opinions on the best way to solve this?

See Benjamin's reply. If wanted to add that there is a macro for
generating the conversion function :

Make_Flags_val(Font_style_val) 

which defines Flags_Font_style_val that converts a `font_style list'
into an integer by or'ing the values.

-- 
   Olivier