Re: [RFC PATCH 00/12] QOM/QAPI integration part 1

[Paolo Bonzini]

On 11/4/21 10:07, Kevin Wolf wrote:
> > Also, for the obligatory bikeshedding remark, do you have any other plans or
> > ideas for the colon-separated auto generated typenames?  Having both the
> > "namespace" (qom) and the more specific use (config) before the classname is
> > a bit weird, compared to the existing structs like RngRandomProperties.
> > Especially if boxed config is more used (or becomes the only possibility),
> > it might be that qom:class-name:config, or even just class-name:config, make
> > for nicer code in the object implementation.
>
> 'qom-config:classname' isn't a type that is useful for the object
> implementations at all. Its only use is really storing the whole
> configuration temporarily in a QAPI C struct before applying it.

<rubbish>
It would be useful as the (auto-boxed) argument of the configuration 
code.  So basically you'd not need the RngProperties function anymore 
because you use something like QomConfigRngBackend (or 
RngBackendQomConfig - hence the question on how to name the 
auto-generated types).
</rubbish>

> The class implementations always want to store only their "local" config
> options, but 'qom-config:classname' contains those of the parent class
> as well.

Ah, I didn't understand that (hence the rubbish tag above).  It makes 
sense given that instance_config is called per-class while ObjectOptions 
stores all the info in one class.  That's a major change from my sketch, 
which planned to call the base class config function by hand (and handle 
the marshalling via QAPI 'base': '...').

> Oh, and I also wanted to say something about why not just directly using
> the class name, which was my first idea: 'foo': 'iothread' looks more
> like referencing an existing iothread rather than the configuration for
> a new one. I wanted to leave us the option that we could possibly later
> take a string for such options (a QOM path) and then pass the referenced
> object to QMP commands as the proper QOM type.

I agree that 'iothread' is going to be confusing when you're referring 
to the configuration.

Anyway I'm totally fine with 'qom-config:classname'.  Given this 
explanation, however, one alternative that makes sense could be 
'classname:full-config'. Then you could use 'classname:config' for the 
autoboxed configs---and reserve 'classname' to mean the pointer to an 
object.  Classes are (generally) lowercase and QAPI structs are 
CamelCase, so there is not much potential for collisions.

Paolo