[Qemu-devel] Re: [PATCH 2/7] monitor: Handle new and old style handlers

[Luiz Capitulino <lcapitulino@redhat.com>]

On Thu, 17 Sep 2009 08:39:25 +0200
Paolo Bonzini <bonzini@gnu.org> wrote:

> On 09/16/2009 11:32 PM, Luiz Capitulino wrote:
> > +    return (cmd->user_print == NULL ? 0 : 1);
> 
> cmd->user_print != NULL.

 Right.

> I would actually inline it at the use point.  Also, calling a function 
> with an extra argument is fine, so while keeping the void* handler you 
> can do:
> 
> +        QObject *data = NULL;
> +        int (*handler_new)(Monitor *mon,
> +                           const QDict *params, QObject **ret_data);
> 
> +        handler_new = cmd->handler;
> +        handler_new(mon, qdict, &data);
> 
> +        if (cmd->user_print)
> +                cmd->user_print(mon, data);
> +        if (data)
> +                qobject_decref(data);
> 
> If you do not like calling the function with the "wrong" number of 
> arguments, you can mass-convert the functions to the new prototype new 
> and leave anyway user_print == NULL.

 The problem is that the monitor_handler_ported() branch can
have additional code in the future (eg. protocol emission code),
so different branches makes things easier to understand.

> What are the plans for the return code of handler_new?

 The protocol emission code will use it to emit 'error' or
'success' messages.