Using Python argparse for Command‑Line Argument Parsing

argparse is a core module in Python's standard library that simplifies building command‑line tools by handling argument parsing, automatic help generation, and error handling.

Basic usage : create a parser with import argparse\nparser = argparse.ArgumentParser(description="Program description") , then add arguments. Positional arguments are required and defined with parser.add_argument("input_file", help="Input file path") . Optional arguments use a leading - or -- , e.g., parser.add_argument("-v", "--verbose", action="store_true", help="Enable verbose mode") . Parse with args = parser.parse_args() and access values like args.input_file .

Parameter types and configuration : specify types with type=int (e.g., parser.add_argument("--size", type=int, default=10, help="Size value") ), enforce required options with required=True , and create mutually exclusive groups via group = parser.add_mutually_exclusive_group() followed by group.add_argument("--enable", action="store_true") and group.add_argument("--disable", action="store_true") .

Advanced features : use sub‑parsers for sub‑commands similar to git commit ( subparsers = parser.add_subparsers()\nparser_a = subparsers.add_parser("cmd1", help="Sub‑command 1")\nparser_a.add_argument("--option") ) and define actions like store_true for boolean flags.

Best practices : provide clear help messages for each argument, set sensible default values, and rely on argparse's automatic validation to reduce manual error handling.

Complete example :

import argparse\n\ndef main():\n    parser = argparse.ArgumentParser(description="File processing tool")\n    parser.add_argument("input", help="Input file path")\n    parser.add_argument("-o", "--output", help="Output file path", default="output.txt")\n    parser.add_argument("--size", type=int, default=100, help="Processing size")\n    parser.add_argument("-v", "--verbose", action="store_true", help="Verbose mode")\n    args = parser.parse_args()\n    if args.verbose:\n        print(f"Processing {args.input}, output to {args.output}")\n\nif __name__ == "__main__":\n    main()\n\n# Run example:\n# python script.py input.txt -o result.txt --size 200 -v

Conclusion : argparse offers flexible command‑line argument parsing suitable for simple scripts to complex tools; by leveraging types, sub‑commands, and mutually exclusive groups, developers can create user‑friendly CLI applications.