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Level 0 / Project 11 - Simple Menu Loop

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Concept This project — Quiz Flashcards Diagram Browser

Estimated time: 25 minutes

Focus

  • while loops and command menu flow

Why this project exists

Build a text-based menu that dispatches numbered choices to action functions. You will practise while loops, if/elif dispatch, and processing batch commands from a file -- the pattern behind every CLI tool.

Run (copy/paste)

Use <repo-root> as the folder containing this repository's README.md.

cd <repo-root>/projects/level-0/11-simple-menu-loop
python project.py --input data/sample_input.txt
pytest -q

Expected terminal output

=== Simple Menu ===
  1. Greet
  2. Reverse text
  3. Count characters
  4. Quit

  [1] => Hello, World!
  [2] => nohtyP
  [3] => "programming" has 11 characters

3 commands processed. Output: data/output.json
5 passed

Expected artifacts

  • data/output.json
  • Passing tests
  • Updated notes.md

Checkpoint: Baseline code runs and all tests pass. Commit your work before continuing.

Alter it (required) — Extension

  1. Add a new menu action: "5. Count vowels" that counts vowels in a given string.
  2. Add a --verbose flag that prints the menu before each action in batch mode.
  3. Re-run script and tests.

Break it (required) — Core

  1. Enter choice 99 -- does execute_choice() handle unknown options gracefully?
  2. Enter choice quit in the middle of the batch file -- does run_batch() stop processing?
  3. Enter an action with no argument like just 1 with no name -- what happens?

Fix it (required) — Core

  1. Ensure execute_choice() returns a clear error message for unknown choices.
  2. Handle missing arguments by using a default value (e.g. "World" for greet).
  3. Add a test for the missing-argument edge case.

Checkpoint: All modifications done, tests still pass. Good time to review your changes.

Explain it (teach-back)

  1. Why does run_batch() use a for loop instead of a while loop?
  2. What is the advantage of mapping menu choices to functions in the actions dict?
  3. Why does the menu loop break on "quit" instead of using sys.exit()?
  4. Where would menu-driven interfaces appear in real software (CLI tools, admin consoles, kiosk systems)?

Mastery check

You can move on when you can: - run baseline without docs, - explain one core function line-by-line, - break and recover in one session, - keep tests passing after your change.

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