PyInstaller can have unexpected behavior if an `__init__.py ` parses the sys args

Question

I have a package dep, where the dep/__init__.py will parse the sys.argv

# dep/__init__.py
import sys

expected_args = ['--arg']

for arg in sys.argv:
    if arg not in expected_args:
        print(f"Got unexpected arg: {arg}")

my MAIN is

# main.py
import dep
if __name__ == '__main__':
    print("hello world")

If I call pyinstaller main.py, PyInstaller will import all its dependencies and run all __init__.py, this will result in "Got unexpected arg:"

where the args are PyInstaller\isolated\_child.py, 1300(a random number for PyInstaller IO), 1296(a random number for PyInstaller IO)

How to avoid this issue?

Answer 1

When you import a module that has code written in the global scope, the code is run immediately upon import. In order to avoid this, just wrap it in a function.

dep.py

import sys

def check_args():
    expected_args = ['--arg']
    for arg in sys.argv:
        if arg not in expected_args:
            print(f"Got unexpected arg: {arg}")

__main__.py

import dep
if __name__ == '__main__':
    print("hello world")
    dep.check_args()