Argparse CLI

Introduction

Argparse builds command-line interfaces with argument parsing and help documentation.

Basic Arguments

import argparse

parser = argparse.ArgumentParser(description="My program")
parser.add_argument("name", help="Your name")
parser.add_argument("-a", "--age", type=int, help="Your age")
parser.add_argument("-v", "--verbose", action="store_true")

args = parser.parse_args()
print(f"Hello {args.name}!")

Argument Types

parser.add_argument("-n", "--number", type=int, default=0)
parser.add_argument("-f", "--file", type=argparse.FileType("r"))
parser.add_argument("-c", "--count", choices=["a", "b", "c"])
parser.add_argument("-e", "--exclude", nargs="*")

Subcommands

parser = argparse.ArgumentParser()
subparsers = parser.add_subparsers()

sub = subparsers.add_parser("build")
sub.add_argument("-o", "--output")

clean = subparsers.add_parser("clean")

Practice Problems

1. Create CLI calculator
2. Add argument validation
3. Implement subcommands
4. Format help text
5. Use argument groups