Calling a python argparse interface from python without Subprocess

Question

Consider the following toy python application, which only have argparse CLI argparse interface.

import argparse

def main():
    parser = argparse.ArgumentParser(description="Printer")
    parser.add_argument("message")
    args = parser.parse_args()
    print(args.message)

if __name__ == "__main__":
    main()

I want to use it from another python script,

• without having to refactor the toy example (because it might be laborious, or maybe I do not have permission to modify it)
• without calling a python Subprocess (because it breaks the call stack, sometimes break pycharm debugger, and make debugging harder in general).

Any way to achieve this ?

Answer 1

you can manipulate the sys.argv list to get your intended behavior.

import argparse

def main():
    parser = argparse.ArgumentParser(description="Printer")
    parser.add_argument("message")
    args = parser.parse_args()
    print(args.message)

if __name__ == "__main__":
    import sys
    sys.argv = [sys.argv[0]]  # remove original arguments except the path
    sys.argv.append('hello')
    main()

hello

make sure to save sys.argv.copy() somewhere to reset it once your function is done.