Re: [Qemu-devel] [PATCH 11/21] qdev: move bus properties to abstract superclasses

[Anthony Liguori]

On 05/02/2012 04:50 PM, Paolo Bonzini wrote:
> Il 02/05/2012 22:00, Anthony Liguori ha scritto:
>
> > Classes are first class objects and can contain members, but I don't
> > know of any system where you actively look at the same field in a
> > super class for each class in the hierarchy. That's really trippy.
>
> Just because it's new to you.  Smalltalk has been doing that for 30-odd
> years.

Ok, I've played around quite a bit with Python now and you are right.  But I 
still don't like what you're proposing.  I have two main reasons:

1) I think it's too clever.  I understand you disagree and this wouldn't be a 
sticking point for me but nonetheless, I want to register that compliant :-)

2) If you do introspection in this method, it means that *all* properties have 
to be registered as static properties to be introspected.  That's a blocker for 
me.  We're always going to need to do the object_new() + enumerate + 
object_delete() trick in order to introspect non-static properties.

> Of course the VM has a lot of caching going on, but it's entirely
> internal.
>
> > If we move properties to Object, I'd rather just stick a property
> > pointer in TypeInfo and call it a day. I'm not thrilled about it, but
> > I feel a lot better about it the above.
>
> What if we add declarative links or children, for example?  Adding more
> junk to TypeInfo is not the solution.

Yes, I dislike this too.  It was a suggestion of a lesser evil although in 
retrospect, it's not much less of an evil.

Regards,

Anthony Liguori

> Paolo