Add CMake option to install pip metadata when Python bindings are installed just by CMake #21611
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…talled just by CMake
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For what regard documentation, this is a packager-oriented option, so I do not know where is the best place where to document this. |
| endif() | ||
| file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/METADATA "") | ||
| file(APPEND ${CMAKE_CURRENT_BINARY_DIR}/METADATA "Metadata-Version: 2.1${NEW_LINE}") | ||
| file(APPEND ${CMAKE_CURRENT_BINARY_DIR}/METADATA "Name: opencv-python${NEW_LINE}") |
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opencv-python
It is just a name of the package from dedicated repository: https://github.com/opencv/opencv-python
It is not an entity of this upstream repository. Perhaps we should not have it here.
Moreover there are several conflicting subpackages from "opencv-python", like headless or contrib variants.
Ubuntu's python3-opencv package also doesn't know anything about opencv-python names:
- 18.04: https://packages.ubuntu.com/bionic/amd64/python3-opencv/filelist
- 20.04: https://packages.ubuntu.com/focal/amd64/python3-opencv/filelist
/METADATA
Modern Python uses PKG-INFO: https://www.python.org/dev/peps/pep-0314/
Not sure about "conda".
Examples:
- https://packages.ubuntu.com/bionic/amd64/python-numpy/filelist
- https://packages.ubuntu.com/bionic/amd64/python3-numpy/filelist
tries to install a Python library that depends on
opencv-python
Are there another ways to mask package installation in pip?
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opencv-pythonIt is just a name of the package from dedicated repository: https://github.com/opencv/opencv-python
It is not an entity of this upstream repository. Perhaps we should not have it here.Moreover there are several conflicting subpackages from "opencv-python", like headless or contrib variants.
Ubuntu's python3-opencv package also doesn't know anything about opencv-python names:
Ack, I see why you may not want CMake's upstream to enter in this details that are mostly related to distributions (and mixing two different distribution, the base apt/conda system and pip).
Modern Python uses PKG-INFO: https://www.python.org/dev/peps/pep-0314/
I am not an expert, I got the METADATA info from official Python documentation (and from PyPI's opencv-python installations):
- https://packaging.python.org/specifications/recording-installed-packages/
- https://packaging.python.org/en/latest/specifications/core-metadata/#core-metadata
From a quick search, it seems that it was introduced by the following PEPs that amend/complete pep-0314:
tries to install a Python library that depends on
opencv-pythonAre there another ways to mask package installation in pip?
That I am aware of, just passing to pip the --no-deps, that however do not install any dependency at and needs to be specified manually by users.
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@traversaro Thank you for information!
I have looked a bit on this specification: https://www.python.org/dev/peps/pep-0345/
There is a field to declare package name aliases (which wold work for us): Provides-Dist
E.g. we could have package name opencv and define known package aliases with names: opencv-python, opencv-python-headless.
But, looks like installation tools don't care about this field: https://stackoverflow.com/questions/61603438/do-any-tools-support-provides-dist-metadata-for-python-packages-if-not-why
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I am a random dude, who would like this feature to be implemented.
Regarding the package name, how about just making the OPENCV_PYTHON_PIP_METADATA_INSTALL option accept a String instead of a boolean and use that name everywhere opencv_python/opencv-python currently appears (with appropriate _/- translations)? This way, downstream package distributors could choose the appropriate name themselves?
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Just a curiosity, what is the use case for you for using this feature?
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I use ArchLinux and I normally prefer to install my python packages through pacman/AUR. The official python-opencv arch package builds and installs opencv from source (including the python bindings). This leads to the problems described by @traversaro, where pip doesn't know, that opencv is already installed. Currently, I roll my own PKGBUILD that installs the appropriate dist-info alongside the system-wide opencv package, but this is obviously inconvenient.
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What is current status of this PR? It should help to make our build visible to pip as |
When OpenCV's Python bindings are installed only via CMake by enabling the appropriate CMake option, the
opencv-pythonpackage is not listed bypip list.This is not problematic until a user tries to install a Python library that depends on
opencv-pythonviapip install .. In that case, the Pythonopencv-pythonpackage already available in the system is ignored, and the PyPI version ofopencv-pythonis installed itself.This PR adds the CMake logic to generate the necessary
METADATAandINSTALLERPython files so that even when just installed via cmake, theopencv-pythonpython package can be listed bypip list.This logic is disabled by default, but can be enabled by the option
OPENCV_PYTHON_PIP_METADATA_INSTALL, to avoid conflicts with existing installation script of Python bindings in https://github.com/opencv/opencv-python that generate these metadata files viasetup.py.This PR originated from conda-forge/opencv-feedstock#299 and has been validated in conda-forge/opencv-feedstock#300, but it can be useful for all downstream packagers of OpenCV's python bindings. For example, Debian's
python3-opencvis affected by the same problem.Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
Patch to opencv_extra has the same branch name.