Generic boilerplate code for setting __package__ attribute for relative imports

_.md

Supplement for my answer on Stack Overflow.

Please treat it as a proof of concept rather than an actual solution. It isn't well-suited for use in real-world code.

one_level_example.py

# level = 1

if __name__ == '__main__' and __package__ is None:
    import_parents()

from . import module
from .module.submodule import thing

PEP366_boilerplate.py

import sys, importlib
from pathlib import Path


def import_parents(level=1):
    global __package__
    file = Path(__file__).resolve()
    parent, top = file.parent, file.parents[level]
    
    sys.path.append(str(top))
    try:
        sys.path.remove(str(parent))
    except ValueError: # already removed
        pass

    __package__ = '.'.join(parent.parts[len(top.parts):])
    importlib.import_module(__package__) # won't be needed after that


if __name__ == '__main__' and __package__ is None:
    import_parents(level=...)

three_levels_example.py

# level = 3

if __name__ == '__main__' and __package__ is None:
    import_parents(level=3)

from ... import module
from ...module.submodule import thing

Hi, I really like your solution to this issue. I am wondering: What is the purpose of removing the script's directory from the system path?
sys.path.remove(str(parent))

I have recently posted this question to SO (with no answer yet):
https://stackoverflow.com/questions/49809290/package-modules-path-hinders-python-intra-package-imports