* Kevin Wolf (kwolf(a)redhat.com) wrote:
Am 25.10.2021 um 07:25 hat Markus Armbruster geschrieben:
> By convention, names starting with "x-" are experimental. The parts
> of external interfaces so named may be withdrawn or changed
> incompatibly in future releases.
>
> Drawback: promoting something from experimental to stable involves a
> name change. Client code needs to be updated.
>
> Moreover, the convention is not universally observed:
>
> * QOM type "input-barrier" has properties "x-origin",
"y-origin".
> Looks accidental, but it's ABI since 4.2.
>
> * QOM types "memory-backend-file", "memory-backend-memfd",
> "memory-backend-ram", and "memory-backend-epc" have a
property
> "x-use-canonical-path-for-ramblock-id" that is documented to be
> stable despite its name.
>
> We could document these exceptions, but documentation helps only
> humans. We want to recognize "unstable" in code, like
"deprecated".
>
> Replace the convention by a new special feature flag "unstable". It
> will be recognized by the QAPI generator, like the existing feature
> flag "deprecated", and unlike regular feature flags.
>
> This commit updates documentation and prepares tests. The next commit
> updates the QAPI schema. The remaining patches update the QAPI
> generator and wire up -compat policy checking.
>
> Signed-off-by: Markus Armbruster <armbru(a)redhat.com>
Obviously, replacing the old convention gets rid of the old drawbacks,
but adds a new one: While using x- makes it very obvious for a human
user that this is an unstable feature, a feature flag in the schema will
almost certainly go unnoticed in manual use.
Agreed, I'd keep the x- as well.
Having said that, the x- represents a few different things (that we
don't currently distinguish):
- experimental
- for internal use
- for debugging/human use
Dave
Kevin
--
Dr. David Alan Gilbert / dgilbert(a)redhat.com / Manchester, UK