[libcamera-devel] [RFC PATCH 0/6] Remove using namespace in header files

[Laurent Pinchart]

Hi Hiro,

On Tue, Oct 05, 2021 at 04:31:08PM +0900, Hirokazu Honda wrote:
> According to Google C++ style guide, using-directives (i.e.
> "using namespace foo") should not be used. However, libcamera has
> been using the scheme in many files. Removing using-directives
> entirely in the code definitely needs the dicussion.

Indeed, that would need discussions :-) Part of the discussion would
likely touch the namespace name, libcamera is fairly long.

> This patch series resolves the porblem of using using-directives
> in header file, which I expect I can handily get the agreement
> from developers. Using-directives in a header file is propagated
> to all the files including the header file. This pollutes
> namespace severely.

Overall it looks fine to me, although I'm not sure it's such a big deal.
Yes, using directives are propagated, which is a bad idea in general,
but the header files below are all internal the the component they
relate to. The risk of namespace polution is thus more theoretical than
practical.

This being said, we're already using this policy in the HAL headers, and
I don't object extending it to all headers. I'll side with the majority.

> [1] https://google.github.io/styleguide/cppguide.html#Namespaces
> 
> Hirokazu Honda (6):
>   ipa: raspberrypi: agc: Remove using namespace in agc.hpp
>   cam: Remove using namespace in stream_options.h
>   qcam: Remove using namespace in header files
>   v4l2: Remove using namespace in header files
>   lc-compliance: Remove using namespace in header files
>   test: Remove using namespace in header files
> 
>  src/cam/stream_options.h                      |  8 ++--
>  src/ipa/raspberrypi/controller/rpi/agc.cpp    |  7 ++++
>  src/ipa/raspberrypi/controller/rpi/agc.hpp    |  6 +--
>  src/lc-compliance/environment.cpp             |  2 +-
>  src/lc-compliance/environment.h               |  8 ++--
>  src/qcam/dng_writer.h                         | 10 ++---
>  src/qcam/main.cpp                             |  2 +-
>  src/qcam/main_window.h                        | 40 +++++++++----------
>  src/v4l2/v4l2_camera.h                        | 37 +++++++++--------
>  src/v4l2/v4l2_camera_proxy.h                  | 15 ++++---
>  src/v4l2/v4l2_compat_manager.h                |  4 +-
>  test/camera/camera_reconfigure.cpp            |  1 +
>  test/camera/capture.cpp                       |  1 +
>  test/camera/configuration_default.cpp         |  1 +
>  test/camera/configuration_set.cpp             |  1 +
>  test/camera/statemachine.cpp                  |  1 +
>  test/gstreamer/gstreamer_test.h               |  2 -
>  test/libtest/buffer_source.cpp                |  2 +
>  test/libtest/buffer_source.h                  | 10 ++---
>  test/libtest/camera_test.h                    |  6 +--
>  test/mapped-buffer.cpp                        |  1 +
>  test/media_device/media_device_test.h         |  6 +--
>  test/serialization/serialization_test.h       | 10 ++---
>  test/v4l2_subdevice/v4l2_subdevice_test.h     |  8 ++--
>  test/v4l2_videodevice/buffer_sharing.cpp      |  2 +
>  test/v4l2_videodevice/capture_async.cpp       |  2 +
>  test/v4l2_videodevice/v4l2_videodevice_test.h | 14 +++----
>  27 files changed, 100 insertions(+), 107 deletions(-)

-- 
Regards,

Laurent Pinchart