[Buildroot] [PATCH 1/1] package/opencv3: python support needs .py modules

[Arnout Vandecappelle]

On 13/09/2019 22:10, Thomas Petazzoni wrote:
> On Sun, 8 Sep 2019 17:48:46 +0200
> Arnout Vandecappelle <arnout at mind.be> wrote:
> 
>> On 05/09/2019 20:44, Fabrice Fontaine wrote:
>>> Fixes:
>>>  - https://bugs.buildroot.org/show_bug.cgi?id=12171  
>>
>>  To make sure this thread stays readable, I'll repeat the relevant part of the
>> bug report, which should have been part of the commit message:
>>
>> When importing cv2 in python 3.7, the program stops with:
>>
>>   File "usr/lib/python3.7/site-packages/cv2/__init__.py", line 89, in <module>
>>   File "usr/lib/python3.7/site-packages/cv2/__init__.py", line 58, in bootstrap
>>   File "usr/lib/python3.7/site-packages/cv2/__init__.py", line 56, in
>> load_first_config
>> ImportError: OpenCV loader: missing configuration file: ['config.py']. Check
>> OpenCV installation.
>>
>> Since buildroot removed all *.py, leaving the corresponding *.pyc, the above
>> config.py file is not in target.
> 
> It is a bit weird/funky for OpenCV to require a .py file just for this.
> It contains a single variable:
> 
> BINARIES_PATHS = [
>     @CMAKE_PYTHON_BINARIES_PATH@
> ] + BINARIES_PATHS
> 
> And then the code looks like this:
> 
>     def load_first_config(fnames, required=True):
>         for fname in fnames:
>             fpath = os.path.join(LOADER_DIR, fname)
>             if not os.path.exists(fpath):
>                 if DEBUG: print('OpenCV loader: config not found, skip: {}'.format(fpath))
>                 continue
>             if DEBUG: print('OpenCV loader: loading config: {}'.format(fpath))
>             exec_file_wrapper(fpath, g_vars, l_vars)
>             return True
>         if required:
>             raise ImportError('OpenCV loader: missing configuration file: {}. Check OpenCV installation.'.format(fnames))
> 
>     load_first_config(['config.py'], True)
>     load_first_config([
>         'config-{}.{}.py'.format(sys.version_info[0], sys.version_info[1]),
>         'config-{}.py'.format(sys.version_info[0])
>     ], True)
> 
> So all it does is override the BINARIES_PATH array with some additional
> value. I'm sure we can replace this with reading a simple text file
> that does the exact same thing without requiring to compile/exec a .py
> file.

 I agree that this approach is insanely and needlessly complicated. However, do
we really want to produce a pretty large package patch to simplify this, which
is probably not even upstreamable because it would break existing installations
that have overridden config.py?


 Regards,
 Arnout


> 
> Best regards,
> 
> Thomas
>