【CLI】`argument parser` explained

1. What is the argument parser

argument parser(used as argparse) is a Python module that provides a mechanism for parsing command-line arguments.
You can specify the arguments your program expects and argparse will automatically generate help and usage messages, handle user input, and parse the command-line arguments into Python variables.

2. Example

・Example Code

import argparse

# Create the parser
parser = argparse.ArgumentParser(description="A simple argument parser example")

# Add arguments
parser.add_argument('--name', type=str, help='Your name')
# parser.add_argument('name', type=str, help='Your name')
parser.add_argument('--age', type=int, default=30, help='Your age', required=True)


# Parse the arguments
args = parser.parse_args()

# Access the arguments
print(f"Hello, {args.name}! You are {args.age} years old.")

・Example CLI

python script.py --name Alice --age 25

・Result

Hello, Alex! You are 20 years old.

As you can see, args can treat all arguments from CLI. It's useful!

2.1 Features

The arguments of add_argument() are here.
・'name'
argument name, required.
・'--name'
argument name, option. Not required.
・type
type restrict of arguments
・default
Default value when user doesn't specify the argument.
・required
The argument became required one even with prefix '--', but it have to specify like python script.py --name Bill. If 'name'(no '--'), you can specify without 'name' like this python script.py Bill.
・help
The message that be shown when python script.py help, like this.

python script.py help
# Output
# usage: script.py [-h] [--name NAME] --age AGE
# script.py: error: the following arguments are required: --age

・choices=['red', 'blue', 'green']
Can restrict arguments to a limited set of choices
・action='store_true'
Running the script with --augment_name sets args.verbose to True

Exclusive Arguments

You can define arguments that cannot be used together using add_mutually_exclusive_group().

group = parser.add_mutually_exclusive_group()
group.add_argument('--verbose', action='store_true')
group.add_argument('--quiet', action='store_true')

3. Summary

This time, I explained about argument parser. It is used in various scene, let you try to use.