Build a Todo CLI

A CLI (Command Line Interface) is the perfect way to learn about file I/O, argument parsing, and data persistence without the complexity of a web UI.

1. The Blueprint (Requirements)

We want to build a tool that lets us:

• add a task
• list all tasks
• done a task (mark as completed)
• remove a task

2. Step-by-Step Implementation

Step 1: Handling Commands

The program should look at the arguments passed in.

Conceptual Logic:

if command == "add":
    add_task(arguments)
elif command == "list":
    show_all_tasks()

Step 2: Persistence

We need a place to store the tasks so they don't disappear when the program closes.

• Option 1: JSON File: Simple, readable, and easy to parse.
• Option 2: SQLite: Better if you have thousands of tasks and need complex searching.

3. Implementation Logic

1. Read: Load the existing JSON file into memory.
2. Modify: Add or remove the task from the list.
3. Write: Save the memory list back to the JSON file.

Key Takeaway

Building a CLI teaches you the core "CRUD" (Create, Read, Update, Delete) cycle that powers almost every software system in the world.