Am 09.12.2011 14:08, schrieb Anthony Liguori: > On 12/09/2011 05:26 AM, Kevin Wolf wrote: >> Am 02.12.2011 21:20, schrieb Anthony Liguori: >>> This really shows the power of dynamic object properties compared to qdev >>> static properties. >>> >>> This property represents a complex structure who's format is preserved over >>> the >>> wire. This is enabled by visitors. >>> >>> It also shows an entirely synthetic property that is not tied to device >>> state. >>> >>> Signed-off-by: Anthony Liguori<aligu...@us.ibm.com> >> >> There's one thing that I was hoping to find answered when I would have >> reviewed the whole series, but it hasn't happened: There is no doubt >> that dynamic properties (in the sense of being able to modify them after >> constructions) are a useful thing. But you also claim that class-based >> properties are not enough for QOM and that we need object-based ones, >> which is a requirement not immediately obvious to me. >> >> Can you provide some examples where we would explicitly need >> object-based properties? > > Sure. Any property that's dynamic needs to be object based. A good example > would be PCI slots. > > Today, we unconditionally advertise 32 slots in our ACPI tables. It could be > desirable to eventually make this configurable. So you can imagine where you > would have an 'slot-count' property and if that was set to 16, it would > result > in 'slot[0]..slot[15]' being created. > > There are other good examples too.
So is it mostly about variably sized arrays, which just happen to be considered independent properties in your approach? Or are there cases where a logically separate property may be there or missing depending on some condition, or possibly even that a new property is created during runtime? Kevin
