Arg Parser Lessons

A step-by-step learning repo for building command-line interfaces in Python using sys.argv and argparse, ending with two packaged, production-style CLI projects.

Structure

• Lesson1/ — minimal ArgumentParser setup
• Lesson2/ — sys.argv basics + motivation for argparse
• Lesson3/ — core argparse patterns (positional/optional args, flags)
• Lesson4/ — argument groups, metavar, custom validators
• Lesson5/ — advanced patterns (exclusive groups, subcommands, shared options)
• Lesson6/ — robust error handling + 2 deployable projects

Each lesson folder contains a README.md with runnable examples.

Lesson 6 Projects

• Lesson6/text_processor/ — packaged CLI textproc (text transformations)
• Lesson6/todo-manager/ — packaged CLI todo (persistent todo manager)

Getting started

• Install Python (3.x recommended)
• Run scripts from inside each lesson folder, e.g.:

python some_script.py --help

Notes for GitHub

• This repo ignores virtual environments, Python caches, and .env files via .gitignore.
• Example env templates like .env.example are allowed.