有没有一种方法可以在 python 中传递 0 命令行 arguments 并且如果传递了特定参数则具有相同的结果？

Question

I am fairly new to Python. I need a piece of code to run when either (i) No command line arguments are passed (ii) A particular command line argument, say "help", is passed

I have tried working with argparse and sys but I can't seem to get both to work.

For the argparse, I tried "default='help'" while adding the argument: parser=add_argument("arg1",default="help")

For the sys.argv, I tried the following code:

if (sys.argv[1] == 'help') or not (len(sys.argv) > 1)

But this just gave me an "Index out of range" error.

Answer 1

import argparse
parser = argparse.ArgumentParser()
parser.add_argument("--arg1", default="help")
args = parser.parse_args()

def help():
    print("I'm here to help, sorta")

if args.arg1 == "help":
    help()

Running this without any command line arguments will output the help message. Running this with python3 program.py --arg1 help (assuming this code is in the file program.py) will also output the help message. Finally, running python3 program.py --arg1 nohelp will not output the help message (not just 'nohelp', but anything other than 'help').