How to load a custom Python module utilizing some program's symbols into that program?

Question

I'm creating a custom Python module for a C application and the Python interpreter that runs in it. I have a problem, was trying with SWIG and now with Cython, and the result is the same:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/root/Dokumenty/app/ext.py", line 15, in <module>
    from _mc import *
ImportError: /root/Dokumenty/app/ext.so: undefined symbol: \
    edit_widget_is_editor

i.e.: an unresolved symbol (↔ a function from the application that's being used in the module's implementation) is being reported during the module import in the embedded interpreter despite the fact that all application's symbols are right there, loaded into it… …aren't they?

How to solve this problem? SWIG on one doc page said to "link whole application" with the Python .so module, however that's IMHO a nonsense — it'll create separate set of symbols (confirmed) basically tearing the module and the app apart…

How to make the loaded .so Python module acknowledge the symbols that are living in the application image?