What is the init function of a dynamic module in python?

Question

I am getting the same error of these other two questions: ImportError: dynamic module does not define init function, but it does and Cython compiled C extension: ImportError: dynamic module does not define init function

But their solutions are not equal, and didn't work for me as well.

I am trying to call functions of a shared library that I have wrote in c, inside my python program.

I compiled my shared lib like this:

gcc -shared -Wl,-soname,playfaircrack.so -o playfaircrack.so -fPIC playfaircrack.c scoreText.o

I created a module, and inside this module I load this lib with:

cracker = ctypes.cdll.LoadLibrary('./playfaircrack.so')

But when I run the code, I get the following error:

Traceback (most recent call last):
  File "playfair.py", line 2, in <module>
    import playfaircrack
ImportError: dynamic module does not define init function (initplayfaircrack)

Which is very strange, because if I run the python interpreteer, and call directly:

cracker = ctypes.cdll.LoadLibrary('./playfaircrack.so')

I can access the functions of my shared lib.

Any ideas how to solve this? Thank you.

Answer 1

Delete the line

import playfaircrack

in playfair.py and it should work.

Alternatively, rename playfaircrack.so to something else or moved it to a different directory. Python gets confused if you have two files with the same module name, i.e. playfaircrack.py and playfaircrack.so in the same directory. Python tries to import playfaircrack.so, which is no valid Python module, before it gets to playfaircrack.py.