[PATCH v1] Documentation: guides: application-developer: Fix variable shadowing

[Kieran Bingham]

Quoting Barnabás Pőcze (2025-01-30 10:37:22)
> 2025. január 30., csütörtök 10:04 keltezéssel, Kieran Bingham <kieran.bingham at ideasonboard.com> írta:
> 
> > Quoting Barnabás Pőcze (2025-01-30 07:47:15)
> > > The mentioned commit mistakenly introduced a new variable for storing
> > > the camera instead of just assigining to the global variable defined
> > > earlier in the tutorial. Fix that by making it an assignment.
> > >
> > > Bug: https://bugs.libcamera.org/show_bug.cgi?id=252
> > > Fixes: e77a2751100e38 ("treewide: Query list of cameras just once")
> > > Signed-off-by: Barnabás Pőcze <pobrn at protonmail.com>
> > > ---
> > >  Documentation/guides/application-developer.rst | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/Documentation/guides/application-developer.rst b/Documentation/guides/application-developer.rst
> > > index 67f5bd7e7..297586a1c 100644
> > > --- a/Documentation/guides/application-developer.rst
> > > +++ b/Documentation/guides/application-developer.rst
> > > @@ -128,7 +128,7 @@ available.
> > >
> > >     std::string cameraId = cameras[0]->id();
> > >
> > > -   auto camera = cm->get(cameraId);
> > > +   camera = cm->get(cameraId);
> > 
> > I always thought we should be providing a request->camera() helper to
> > return the associated camera with a request to make this easier for
> > applciations but it didn't seem to get any traction when I posted this:
> > 
> >  https://patchwork.libcamera.org/patch/9328/
> 
> I see the camera pointer has been moved to `Request::Private`, but I think
> this still seems like a good idea. Although I have no idea what the mentioned
> plans with `Request` were.

I don't know what the resistance context was either, but I still think
it seems like a useful way to access the camera in the async delivery
especially as the camera is already stored /in/ the request and is
guaranteed to be correctly associated.

Maybe it's worth refreshing the patch to see.

--
Kieran

> 
> Regards,
> Barnabás Pőcze
> 
> > 
> > So for this patch indeed this stops the aliased variable.
> > 
> > 
> > Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > 
> > 
> > >     /*
> > >      * Note that `camera` may not compare equal to `cameras[0]`.
> > >      * In fact, it might simply be a `nullptr`, as the particular
> > > --
> > > 2.48.1
> > >
> > >
> >