Python relative imports using setuptools with scripts

Question

I am transitioning to a package-based workflow for a project I've been working on. I want to be able to separate development and production environments and I think setuptools offers this possibility with some degree of ease.

I have a project structured as follows:

modulename/
    setup.py
    modulename/
         file_a.py
         script.py

In script.py, I want to import file_a.py. Currently I do this by doing import file_a.

My setup.py looks like:

from setuptools import setup, find_packages

setup(name='modulename',
  packages = find_packages(),
  package_dir = {'': '../modulename'},
  scripts = ['modulename/script.py'])

Currently, when I run script.py after doing python setup.py install, I get an error message:

SystemError: Parent module '' not loaded, cannot perform relative import

I have tried a variety of permutations of package_dir = ..., most notably package_dir = {'': 'modulename'}, but this throws another error on install, error: package directory 'modulename/modulename' does not exist

I am not sure what I am doing wrong. The documentation online for setuptools is relatively poor in dealing with situations involving relative imports. Can someone point me in the right direction?

Answer 1

The problem is not related with setuptools. Using relative imports inside the module being executed as __main__ does not work out of the box. There are workarounds / hacks, but the most common solutions seems to be moving the script out of the package or using absolute imports in the script file.

Take a look at Relative imports in Python 3 for the full story.