[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH 3/3] qom: add unit test for Interfaces

From: Andreas Färber
Subject: Re: [Qemu-devel] [PATCH 3/3] qom: add unit test for Interfaces
Date: Mon, 18 Jun 2012 15:51:30 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120421 Thunderbird/12.0

Am 18.06.2012 15:46, schrieb Peter Crosthwaite:
>>>> +#define HERBIVORE(obj) \
>>>> +    INTERFACE_CHECK(Herbivore, (obj), TYPE_HERBIVORE)
>>>> +
>>>> +typedef struct Herbivore
>>>> +{
>>>> +    Object obj;
>>>> +} Herbivore;
>>> All this is doing is saying Herbivores are Objects right? A user cant
>>> add anything to this struct given that interfaces are stateless so
>>> could this be simplified to
>>> typedef Object Herbivore;
>> This is admittedly a little wierd...
>> Interfaces don't exist as Objects in QOM.
> Not in the sense that they used too, but all objects that implement an
> interface are still OBJECTs just through the inheritance path of their
> concrete class, which is the point of this struct yes?
>  They are just classes.  But it's
>> very handy to be able to have a Herbivore type that you can cast objects to.
> Yes I agree in full, but the typedef definition is functionally
> equivalent to what you have there, and removes the temptation to add
> fields to the object type. Having a skeletal struct there gives the
> illusion to readers that interface objects are in someway extensible.

Why have a typedef at all then? You can just use Object directly. If
that ever changes it leads to all kinds of problems (well, necessary
adjustments), as seen in the pci_host series.


SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

reply via email to

[Prev in Thread] Current Thread [Next in Thread]