Re: [Libvir] [PATCH] Check availability of driver calls

On Mon, Aug 20, 2007 at 04:43:27PM +0100, Richard W.M. Jones wrote: > This doesn't work though, because different parts of the system have to > answer different parts of a request such as: > > VIR_DRV_FEATURE_MIGRATION_V1 | VIR_DRV_FEATURE_REMOTE. > > VIR_DRV_FEATURE_MIGRATION_V1 goes through to end driver. > VIR_DRV_FEATURE_REMOTE is answered by the local end of remote > (src/remote_internal.c). My real point is I don't understand the case > where it is ever useful to query more than one feature. My first inclination was to also suggest a bitfield, but looking at the use case now I agree its overkill. If we did ever need to query more than one feature here, the roundtrip time would be dwarfed by the time to do the actual migration.

> >you still pas and return an atomic value, you just need a little bit of > >decoding work at the C level to analyze the bits in the values, but that's > >won't be much more complex than a switch based on the enum, and IMHO > >more reliable, because I still (sorry) consider enums in APIs to be a big > >problem in C. Even if it's considered an internal API, I would avoid enums > >there because of the RPC. > > I meant to get rid of the enums. Attached is a version which uses > macros instead so the type should always be 'int' (ie. ABI stable). Ok, that's fine by me.