如何整理 python 文件，让导入不报 ImportError:?

Question

This question has been asked a million times. However none of the answers seems to be able to solve my problem.

I have a python module, with some scripts embedded in a c++ project. I have the following folder structure:

mcmpy/
  setup.py
  doc/
  mcm/
    __init__.py
    cpp/
      __init__.py
      kindyn.py
    demos/
      __init__.py
      importer.py

in importer.py I tried, and does not work:

• from mcmpy.mcm.cpp import kindyn
• from mcm.cpp import kindyn
• from.cpp import kindyn
• from..cpp import kindyn

What I want to achieve is to have some scripts in demo folder, and be able to run them from terminal with python3 script_name .py

Answer 1

You need to add a __init__.py file inside mcmpy/

mcmpy/
  __init__.py
  setup.py
  doc/
  mcm/
    __init__.py
    cpp/
      __init__.py
      kindyn.py
    demos/
      __init__.py
      importer.py

And inside the mcmpy folder, you just need to

from mcm.cpp import kindyn

Answer 2

To import with from mcmpy.mcm.cpp import kindyn you will need to install this project - pip install -e <path of mcmpy> .