[Qemu-devel] Re: [PATCH 01/25] Introduce QEMU dictionary data type

[Luiz Capitulino]

On Wed, 29 Jul 2009 17:37:31 +0300
Avi Kivity <address@hidden> 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.