[libcamera-devel] [RFC PATCH v3 2/2] libcamera: Remove `StreamRoles` alias

[Barnabás Pőcze]

Hi


2023. május 16., kedd 1:09 keltezéssel, Kieran Bingham <kieran.bingham at ideasonboard.com> írta:

> Quoting Barnabás Pőcze via libcamera-devel (2023-05-10 00:15:43)
> > Now that `Camera::generateConfiguration()` takes a `libcamera::Span`
> > of `StreamRole`, remove the `StreamRoles` type, which was an alias
> > to `std::vector<libcamera::StreamRole>`.
> >
> > The removal has two reasons:
> >  - it is no longer strictly necessary,
> >  - its presence may suggest that that is the preferred (or correct)
> >    way to build/pass a list of `StreamRole`.
> >
> > Signed-off-by: Barnabás Pőcze <pobrn at protonmail.com>
> > ---
> >  include/libcamera/stream.h             | 2 --
> >  src/apps/cam/camera_session.cpp        | 2 +-
> >  src/apps/common/stream_options.cpp     | 4 ++--
> >  src/apps/common/stream_options.h       | 2 +-
> >  src/apps/qcam/main_window.cpp          | 2 +-
> >  src/gstreamer/gstlibcameraprovider.cpp | 5 +++--
> >  src/gstreamer/gstlibcamerasrc.cpp      | 2 +-
> >  src/libcamera/stream.cpp               | 5 -----
> >  8 files changed, 9 insertions(+), 15 deletions(-)
> >
> > diff --git a/include/libcamera/stream.h b/include/libcamera/stream.h
> > index 29235ddf..4e94187d 100644
> > --- a/include/libcamera/stream.h
> > +++ b/include/libcamera/stream.h
> > @@ -69,8 +69,6 @@ enum class StreamRole {
> >         Viewfinder,
> >  };
> >
> > -using StreamRoles = std::vector<StreamRole>;
> > -
> 
> I was curious how we might handle this moving forwards if we need to
> remove things. (I think removing this is the right thing to do, so this
> is just 'how' we remove it)
> 
> I wonder if we should have an include/libcamera/deprecated.h to place
> things like:
> 
> using StreamRoles [[deprecated("Use a span, array or vector directly")]]
>         = std::vector<StreamRole>;
> 
> Perhaps even with a reference to something that makes it clearer what to
> do to migrate with the issue.
> 
> StreamRoles has been in all the examples so far, so I think all apps
> that use libcamera are probably already using this.
> 
> I know we explicitly don't have ABI/API stability - but if we break
> things perhaps it would be helpful to have a system that lets us inform
> the user what they need to do next to fix it again.
> 
> This probably gets quite relevant to how we handle things with:
> https://patchwork.libcamera.org/project/libcamera/list/?series=3877 so
> any thoughts on that series are welcome!

Maybe it could be kept in the same header file? Otherwise users will still
encounter a compiler error and have to investigate what happened, no?


> [...]


Regards,
Barnabás Pőcze