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Re: [PATCH 2/2] qom: use correct field name when getting/setting alias p
Re: [PATCH 2/2] qom: use correct field name when getting/setting alias properties
Wed, 21 Jul 2021 16:43:21 +0200
Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux)
Paolo Bonzini <firstname.lastname@example.org> writes:
> On 20/07/21 03:00, Eric Blake wrote:
>> Deceptively simple; all the work was in the previous patch writing up
>> the forwarding visitor. I still wonder if Kevin's QAPI aliases will
>> do this more gracefully, but if we're trying to justify this as a bug
>> fix worthy of 6.1, this is certainly a smaller approach than Kevin's.
>> Reviewed-by: Eric Blake<email@example.com>
> As discussed on IRC, this is unrelated to QAPI aliases; QOM alias
> properties typically target a property *on a different object*.
Yes, these are different beasts.
A QAPI alias provides an alternate name for a member. The member may be
nested. It's still within the same QAPI object. Can be useful for
maintaining backwards compatibility, in particular for replacing (flat)
QemuOpts by QAPI-based dotted keys.
A QOM alias property is a proxy for a property of an *arbitrary* QOM
object. Not limited to the alias's object and its sub-objects.
Strictly more powerful.
QOM alias properties are created at run time: creation requires the
target object. QAPI aliases are completely defined at compile-time.
> This is a regression, so it certainly has to be fixed in 6.1 one way
> or the other.