Merge pull request #19982 from TolyaTalamanov:at/new-python-operation-api

G-API: New python operations API

* Reimplement test using decorators

* Custom python operation API

* Remove wip status

* python: support Python code in bindings (through loader only)

* cleanup, skip tests for Python 2.x (not supported)

* python 2.x can't skip unittest modules

* Clean up

* Clean up

* Fix segfault python3.9

Co-authored-by: Alexander Alekhin <alexander.a.alekhin@gmail.com>

modules/python/package/cv2/__init__.py

@@ -4,6 +4,8 @@ OpenCV Python binary extension loader
 import os
 import sys
 
+__all__ = []
+
 try:
     import numpy
     import numpy.core.multiarray
@@ -13,6 +15,14 @@ except ImportError:
     print('    pip install numpy')
     raise
 
+
+py_code_loader = None
+if sys.version_info[:2] >= (3, 0):
+    try:
+        from . import _extra_py_code as py_code_loader
+    except:
+        pass
+
 # TODO
 # is_x64 = sys.maxsize > 2**32
 
@@ -97,6 +107,11 @@ def bootstrap():
     except:
         pass
 
+    if DEBUG: print('OpenCV loader: binary extension... OK')
+
+    if py_code_loader:
+        py_code_loader.init('cv2')
+
     if DEBUG: print('OpenCV loader: DONE')
 
 bootstrap()