Python：从命令行启动的脚本中模块的导入错误

Question

There is a custom module "ETPython" generated by SWIG (consists of ETPython.py and binary _ETPython.so ) and a simple script that invokes this module

sample.py

import ETPython
...

There aren't any problems if the script is run in an IDE (pycharm, internal python's IDLE, squish by froglogic so on). But if I'm trying to launch it in python shell in interactive mode or via terminal using

python3 sample.py

there is an error message like:

  File "<path_to_file>/example.py", line 12, in <module>
    import ETPython
  File "<path_to_file>/ETPython.py", line 15, in <module>
    import _ETPython
ImportError: dlopen(<path_to_file>/_ETPython.so, 2): Symbol not found: _NSLog
  Referenced from: <path_to_file>/_ETPython.so
  Expected in: flat namespace

Searching topics, I found that problem is related to wrong paths. So I added some code:

import os, sys
os.chdir("<path_to_dir>")
sys.path.append('<path_to_dir>')
os.system('export PYTHONPATH=<path_to_dir>:$PYTHONPATH')

This code helped to import the module in python shell in interactive mode but launching in terminal is still failing.

So the question is how to make it to work?

Answer 1

I found solution. The SWIG module was compiled incorrectly. There was option for CMake that suppressed errors for undefined symbols

set(PLATFORM_LIBS "-undefined dynamic_lookup" )

That why the module doesn't contain NSLOG symbol. The module was recompiled with additional

"-framework Foundation"

in swig_link_libraries statement. And now the module is imported correctly