[libcamera-devel] [PATCH v3 0/7] Delete Copy-Move-Assign

[Kieran Bingham]

Here's a series which has been niggling me on my task list since the
topic came up which highlighted that the non-copyability of the
FrameBufferAllocator had been incorrectly implemented.

We previously discussed providing a non-copyable class which could be inherited
or the addition of a macro.

I've chosen to go down the macro route, because I think its clearer,
easier to customise, and doesn't extend the inheritance (and thus
increase the size) of classes.

Along the way, the following tasks have occured:

 - Classes which delete their copy constructor and copy assignment
   operator, have had those replaced by LIBCAMERA_DISABLE_COPY_AND_MOVE.
   Where the existing copy/assignment deletion occured in public:, the
   LIBCAMERA_DISABLE_COPY_AND_MOVE addition has been placed in private: so
   that Doxygen does not complain. (and it should have the same effect)

 - The Buffer class deletes all of the copy, and move constructor and
   assignment operators, so this has been kept. But as the only class
   which goes this far, it seems to stand out on its own. I have simply
   converted to the new usage, I didn't want to change any functionality
   here.

 - Media objects deleted only their copy construtor. I believe this to
   be an oversight, as if the copy constructor is deleted, then the copy
   assignment operator should also be deleted. Therefore I see this macro
   as a win here.

 - MappedBuffer : This did not delete it's copy constructor, and I
   believe it should have - so I've added it. I have not done a thorough
   search of the tree to find other instances that should also delete
   anything yet though.

I'm sure that more classes could be tightened up with the addition of
these restrictions where necessary, or perhaps other variants might crop
up. I'm not sure yet, but this can get the ball rolling in that case.


Since the first v1 posting of this series, DELETE_COPY_MOVE_AND_ASSIGN
is renamed to LIBCAMERA_DISABLE_COPY_AND_MOVE (using disable instead of
deleted), and 'assign' has been removed from the macro names.

The extensible class was also merged during this time, so it is first
renamed to be a generic class.h and these macros are added there.

V3 brings in cleanups, added documentation examples, and removes the semi-colon
from all usages throughout the series.

Kieran Bingham (7):
  libcamera: Move extensible to class
  libcamera: class: Provide move and copy disablers
  libcamera: buffer: Utilise LIBCAMERA_DISABLE_COPY_AND_MOVE
  libcamera: media_object: Utilise LIBCAMERA_DISABLE_COPY_AND_MOVE
  libcamera: controls: Utilise LIBCAMERA_DISABLE_COPY_AND_MOVE
  libcamera: Utilise LIBCAMERA_DISABLE_COPY
  libcamera: MappedBuffer: Disable copy and assignment

 include/libcamera/buffer.h                    | 10 ++-
 include/libcamera/camera.h                    |  7 +-
 include/libcamera/camera_manager.h            |  6 +-
 include/libcamera/{extensible.h => class.h}   | 26 +++++--
 include/libcamera/controls.h                  |  7 +-
 include/libcamera/framebuffer_allocator.h     |  7 +-
 include/libcamera/internal/buffer.h           |  4 ++
 .../libcamera/internal/byte_stream_buffer.h   |  4 +-
 include/libcamera/internal/camera_sensor.h    |  6 +-
 include/libcamera/internal/file.h             |  6 +-
 include/libcamera/internal/log.h              |  6 +-
 include/libcamera/internal/media_object.h     | 11 ++-
 include/libcamera/internal/pipeline_handler.h |  4 +-
 include/libcamera/internal/v4l2_subdevice.h   |  5 +-
 include/libcamera/internal/v4l2_videodevice.h |  6 +-
 include/libcamera/meson.build                 |  2 +-
 include/libcamera/request.h                   |  5 +-
 src/libcamera/{extensible.cpp => class.cpp}   | 68 +++++++++++++++++--
 src/libcamera/meson.build                     |  2 +-
 19 files changed, 141 insertions(+), 51 deletions(-)
 rename include/libcamera/{extensible.h => class.h} (66%)
 rename src/libcamera/{extensible.cpp => class.cpp} (77%)

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2.25.1