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Date: Mon, 23 Aug 2010 11:02:08 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH v2 0/7] APIC/IOAPIC cleanup
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To: Avi Kivity <avi@redhat.com>
Cc: Blue Swirl <blauwirbel@gmail.com>, "Liu >> \"Liu,
	Jinsong\"" <jinsong.liu@intel.com>, qemu-devel <qemu-devel@nongnu.org>, Markus Armbruster <armbru@redhat.com>, Paul Brook <paul@codesourcery.com>

On 08/23/2010 10:14 AM, Avi Kivity wrote:
>  On 08/23/2010 05:47 PM, Anthony Liguori wrote:
>>
>>>>
>>>> Devices can contain references to structs and objects.  If a Device 
>>>> contains a reference to an object, the object should be stored in a 
>>>> BusState which is a container of Devices.  Therefore, the object 
>>>> should inherit from Device.
>>>
>>> I disagree.  It's up to the author to decide whether to split a 
>>> Device into 1 or 15 objects.
>>>
>>> If one of the other objects is also a subclass of DeviceState, then 
>>> you're probably violating that DeviceState's contract.  But that's a 
>>> different (and trivial) matter.
>>>
>>> (side point: in C no objects have constructors and methods.  in C++ 
>>> all objects have constructors and methods, even PODs)
>>
>> Things that inherit from DeviceState have ctors/dtors.  Things that 
>> don't end up inventing their own and probably will do so poorly.
>
> you mean misimplement other_state_init(OtherState *) and 
> other_state_destroy(OtherState *)?

And hot plug, save/restore, properties, and all of the other things that 
go along with qdev.

Hot plug is a good example of how easy it is to screw this up by not 
having the right hooks being propagated through the device model.

Regards,

Anthony Liguori