From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1MWBko-0008T0-1m
	for qemu-devel@nongnu.org; Wed, 29 Jul 2009 12:11:46 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1MWBkj-0008Kj-Id
	for qemu-devel@nongnu.org; Wed, 29 Jul 2009 12:11:45 -0400
Received: from [199.232.76.173] (port=48282 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1MWBkj-0008KY-7u
	for qemu-devel@nongnu.org; Wed, 29 Jul 2009 12:11:41 -0400
Received: from mx2.redhat.com ([66.187.237.31]:39509)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <lcapitulino@redhat.com>) id 1MWBki-0003bc-KU
	for qemu-devel@nongnu.org; Wed, 29 Jul 2009 12:11:41 -0400
Date: Wed, 29 Jul 2009 13:11:31 -0300
From: Luiz Capitulino <lcapitulino@redhat.com>
Message-ID: <20090729131131.2d5e4fa6@doriath>
In-Reply-To: <4A705EAB.1030200@redhat.com>
References: <1248818713-11261-1-git-send-email-lcapitulino@redhat.com>
	<1248818713-11261-2-git-send-email-lcapitulino@redhat.com>
	<4A701AA3.4060902@redhat.com> <20090729104600.17deb355@doriath>
	<4A705536.3020305@redhat.com> <20090729112220.16ffe414@doriath>
	<4A705EAB.1030200@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Subject: [Qemu-devel] Re: [PATCH 01/25] Introduce QEMU dictionary data type
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Avi Kivity <avi@redhat.com>
Cc: jan.kiszka@siemens.com, aliguori@us.ibm.com, dlaor@redhat.com, qemu-devel@nongnu.org

On Wed, 29 Jul 2009 17:37:31 +0300
Avi Kivity <avi@redhat.com> wrote:

> On 07/29/2009 05:22 PM, Luiz Capitulino wrote:
> >
> >    
> >> I meant QObject as a base type, so it is a lower layer than QDict; QDict
> >> implements the QObject methods, as do QString, QNumber, etc.
> >>      
> >
> >   Ok, I'm failing at imagining "QDict implements the QObject methods"
> > in C, can you elaborate more and/or sketch something?
> >    
> 
> It's really no different than in other languages, except that you have 
> to write a ton of boilerplate.  The kernel is riddled with object 
> hierarchies:
> 
> typedef struct QType {
>      const char *name;
>      void (*destroy)(QObject *);
>      QObject *(*clone)(QObject *)
> } QType;
> 
> typedef struct QObject {
>     QType *type;
> } QObject;
> 
> typedef struct QDict {
>      QObject base;
>      // hash stuff
> } QDict;
> 
> static QType qdict_type = {
>    .destroy = qdict_destroy,
>    .clone = qdict_clone,
> };
> 
> QObject *qobject_clone(QObject *obj) { return obj->type->clone(obj); }
> 
> QObject *qdict_clone(QObject *obj)
> {
>      ...
> }

 Okay, this is really far away from what I had in my mind, will
start working on this then.

 Thanks a lot for the explanation.

> >> The problem with void *, beyond requiring the user to know what the
> >> object type is, is that it is impossible to control object lifecycle.
> >> When you destroy a QDict containing void *, you cannot destroy the
> >> contained objects.  On the other hand if QDict values are all QObjects,
> >> then qdict_destroy() can call qobject_destroy() on all of them
> >> (qobject_destroy might end up calling qdict_destroy() is a value
> >> happened to be a QDict).
> >>      
> >
> >   Right, but as you said in other email, can we get this merged first
> > and then improve or should I do the change for this series?
> >    
> 
> I think we should merge first, doing this sort of change on a 25-patch 
> series is no fun.

 Thanks a lot again. :)

Btw, the patches that ports command handlers have some void * to
long type conversions (eg. patch 14) can someone please review
them?

 I'm not 100% confident about them.