How to import function from module that uses ArgParser without passing args

Question

Let's say I have two modules:

• a.py:

  import argparse
  
  
  parser = argparse.ArgumentParser()
  parser.add_argument("arg", help="Some argument")
  args = parser.parse_args()
  
  
  def func():
      print('Hello world!')
  

• b.py:

  from a import func
  
  func()
  

When I execute python3.8 '/home/b.py'

I got

usage: b.py [-h] arg
b.py: error: the following arguments are required: arg

...even though func doesn't need to use system arguments to be executed

Is there any way I can import and execute func without passing system arguments to b.py?

Answer 1

You are causing script a.py to run at import time from script b.py. You just need to change it to:

import argparse

if __name__ == '__main__':
    parser = argparse.ArgumentParser()
    parser.add_argument("arg", help="Some argument")
    args = parser.parse_args()


def func():
    print('Hello world!')

Why this works is explained very well here so I won't rehash it! What does if __name__ == "__main__": do?