Re: [Qemu-devel] [PATCH 0/6] refactor PC machine, i440fx and piix3 to take advantage of QOM

[Anthony Liguori <anthony@codemonkey.ws>]

On 03/26/2012 02:44 PM, Jan Kiszka wrote:
> On 2012-03-26 21:39, Anthony Liguori wrote:
>> On 03/26/2012 02:37 PM, Jan Kiszka wrote:
>>> On 2012-03-26 21:35, Anthony Liguori wrote:
>>>>>> Since this is an easily refactorable thing to look at later, I think
>>>>>> we should
>>>>>> start with extracting the types.
>>>>>
>>>>> My worry is that those three refactorings set bad examples for others.
>>>>> So I'd like to avoid such back and forth if possible.
>>>>
>>>> I'm not really worried about it.  It's so easier to refactor this
>>>> later.  Why rush it now?
>>>
>>> You rush changing the current layout, not me. :)
>>
>> No, I'm trying to do incremental changes without boiling the ocean in
>> the process.
>>
>> I think we all are in violent agreement about where we want to end up
>> (as opaque types as possible).  I don't want to hold back additional
>> refactoring on doing this right (and it's not just a matter of
>> malloc/free).
>
> Either I'm missing it in the code shuffling, or it's not part of this
> series: Can you point out where more that a forward reference and
> malloc/free is needed?

Inheritance is the other nasty case.

To inherit from a type, you need to have the type definition.  This is a pretty 
common problem with Object systems and the typical solution is PIMPL[1].

So maybe that's the right thing to do here, but that would have a significant 
affect on the code.  That's what I mean by rushing how to handle this.  There 
are multiple possible solutions and they need to be considered.

The problem is purely aesthetic too, so I don't see a rush to fix it.

[1] http://c2.com/cgi/wiki?PimplIdiom

Regards,

Anthony Liguori

>
> Jan