todo_cli.py in Python

A complete CLI todo list persisting to JSON.

"""A tiny todo list that persists to a JSON file."""
import argparse
import json
from pathlib import Path

TODO_FILE = Path("todos.json")


def load_todos():
    if TODO_FILE.exists():
        return json.loads(TODO_FILE.read_text())
    return []


def save_todos(todos):
    TODO_FILE.write_text(json.dumps(todos, indent=2))


def main():
    parser = argparse.ArgumentParser(description="minimal todo list")
    sub = parser.add_subparsers(dest="command", required=True)
    add = sub.add_parser("add")
    add.add_argument("text")
    done = sub.add_parser("done")
    done.add_argument("number", type=int)
    sub.add_parser("list")
    args = parser.parse_args()

    todos = load_todos()
    if args.command == "add":
        todos.append({"text": args.text, "done": False})
        save_todos(todos)
        print(f"added: {args.text}")
    elif args.command == "done":
        todos[args.number - 1]["done"] = True
        save_todos(todos)
        print(f"completed #{args.number}")
    else:
        for i, todo in enumerate(todos, start=1):
            mark = "x" if todo["done"] else " "
            print(f"[{mark}] {i}. {todo['text']}")


if __name__ == "__main__":
    main()

How it works

1. argparse subcommands give it add, done, and list verbs.
2. State round-trips through a JSON file with pathlib.
3. Each command edits the list and saves it back.

Keywords and builtins used here

• def
• elif
• else
• enumerate
• for
• if
• int
• load_todos
• main
• print
• return
• save_todos
• type

The run, in numbers

Lines

45

Characters to type

1039

Tokens

306

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 175 seconds.

Type this snippet

Step 3 of 5 in Encore, step 70 of 72 in Language basics.

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