Python module: replace config.py files by config.ini #16008
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…ATH_RELATIVE_CONFIGCMAKE when not needed The variable OpenCV_PYTHON_INSTALL_PATH_RELATIVE_CONFIGCMAKE is set in the if(IS_ABSOLUTE ...), but it is not used anywhere afterwards. A variable of the same name is defined and used in the else() clause of the same condition, but it is only used within that else() clause. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
The cv2 Python modules currently reads at runtime some bits of configuration from config.py and config-X.Y.py files, by executing them using execfile() or similar inside the Python interpreter. Unfortunately, this requires having the .py files themselves available, which may not be the case on embedded systems where only the byte-compiled .pyc files are present (the .pyc files are already byte-compiled, and in order to be space-efficient, .py files are not installed on some embedded systems). Due to the lack of .py files, importing the cv2 Python module fails. Since this configuration mechanism is a bit unusual, and also requires separate handling for Python 2 and Python 3, this commit replaces it by using two .ini files, which are generated with the same information as the .py files, but parsed using the standard ConfigParser module of Python. config.ini looks like this: [python] binpath = /usr/lib while config-3.8.ini looks like this: [python] extensionpath = /usr/lib/python3.8/site-packages/cv2/python-3.8 If multiple paths are present, they are stored colon-separated, and they are split again when the configuration files are parsed. The only change relevant mentioning is that the expansion of LOADER_DIR is now done when the configuration is parsed: if we have an absolute path, we take it as-is, if there is a relative path, we assume it is relative to LOADER_DIR. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
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In Python2 it is named ConfigParser.
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Thanks for you contribution! |
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@tpetazzoni any progress on the patch? |
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@asmorkalov No sorry, not yet, I'll try to get to it. |
Consider disabling OpenCV Python bindings loader in your configuration: Perhaps .ini files will not work for us. In the future we want to detect Python distributions in runtime, like Anaconda Python, Intel Python distribution, etc. One package + auto detection/configuration through .py files config. Instead of .ini approach you may take a look in direction of changing of importing approach (use some "import" code instead of "execfile") |
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OpenCV team decided to close the PR as expected behavior is reachable with |
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Well, OPENCV_SKIP_PYTHON_LOADER may not be an option: some people do want the Python bindings of OpenCV available on their embedded system. |
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The OpenCV Python module currently installs and reads at runtime a config.py file and a config-X.Y.py file to retrieve some bits of configuration. This is done using the execfile() Python mechanism, which unfortunately only works with .py files, and not with .pyc files.
However, on some embedded systems, only .pyc files are installed: they are already byte-compiled, which optimizes the startup time, and installating both .pyc and .py files doubles the storage space, which is a limited resource on embedded systems.
In addition, loading .py file requires different code between Python 2 and Python 3.
To solve these issues, this pull request replaces the .py files by .ini files, which can trivially be parsed by the standard ConfigParser Python module.