Re: [Qemu-devel] [PATCH 1/7] Add support for generic notifier lists

[Anthony Liguori <aliguori@linux.vnet.ibm.com>]

On 03/11/2010 08:19 AM, Paul Brook wrote:
>> On 03/11/2010 06:57 AM, Paul Brook wrote:
>>      
>>>> +struct QEMUNotifier
>>>> +{
>>>> +    void (*notify)(QEMUNotifier *notifier);
>>>> +};
>>>>          
>>> I suggest combining this with QEMUBH.
>>>        
>> I take it your not opposed to converting QEMUBH to be a QEMUNotifier?
>> If so, I'm happy to do it.
>>      
> It's unclear to me why you've invented a new thing in the first place.
>    

It's a better approximation of the command pattern because the command 
is a single object as opposed to a tuple.  Because the command is an 
object, you can also do things like binding.  For instance:

Which now gives you a notifier that has an fd bound to it's second 
argument (which is pretty useful for IO dispatch).

You can do this with a tuple representation, but it gets awkward.  One 
could argue for formalizing the tuple as a struct but extending by 
nesting becomes more complicated.  Also, for the most part, you already 
have a state for the command and embedding the object means less dynamic 
memory allocation and less code to handle that.

Regards,

Anthony Liguori