Python CLI Task Manager

A simple command-line task management app built with core Python — no external dependencies. Built as a Phase 1 capstone project to practice functions, file I/O, error handling, decorators, and generators.

Features

• Add, complete, delete, and list tasks
• Persistent storage using JSON Lines (tasks.jsonl)
• Function call logging via a custom decorator (log.txt)
• Memory-efficient task reading using a generator (reads tasks one line at a time instead of loading the whole file into memory)
• Graceful error handling for invalid input, missing files, and corrupted data

Requirements

• Python 3.10+
• No third-party libraries required (standard library only)

How to Run

python main.py

You'll see a menu:

===== TO-DO MENU =====
1. Add Task
2. Complete Task
3. Delete Task
4. List Tasks
5. View Tasks (Generator)
6. Exit

Enter the number corresponding to the action you want, and follow the prompts.

Project Structure

python-task-manager/
├── screenshots/         # Terminal screenshots for documentation
├── log.txt              # Auto-generated function call logs
├── main.py              # Core application logic
├── README.md
├── requirements.txt      # Dependencies (none needed)
└── tasks.jsonl           # Task storage (JSON Lines format, auto-created)

How It Works

Storage Format

Tasks are stored in tasks.jsonl, where each line is an independent JSON object:

{"id": 1, "title": "Dinner", "completed": false, "created_at": "2026-07-06, 09:23 AM"}

This format allows tasks to be read one line at a time without loading the entire file into memory — see the Generator section below.

Decorator Logging

Every core function (add_task, mark_complete, delete_task, etc.) is wrapped with a @log_call decorator that writes a timestamped entry to log.txt every time the function runs, including the arguments passed.

Generator (Memory-Efficient Reading)

The "View Tasks (Generator)" menu option uses read_tasks_generator(), which reads tasks.jsonl line by line using Python's lazy file iteration and yields each task individually — the full file is never loaded into memory at once. This scales well even with a very large task list.

Error Handling

• Invalid menu choices and non-numeric input are caught and handled
• Missing or corrupted tasks.jsonl is handled gracefully (returns an empty task list instead of crashing)
• Invalid task IDs during complete/delete operations are reported without crashing the app

Example Usage

Enter choice: 1
Task title: Buy groceries
Buy groceries Added

Enter choice: 4

Tasks:
1. Buy groceries [✗]

Enter choice: 2
Task ID: 1
Task marked as completed.

Enter choice: 4

Tasks:
1. Buy groceries [✓]

Screenshots

Main Menu

Adding a Task

Listing Tasks

Marking a Task Complete

Generator View

Author

Noman Rizvi (@ProNomanRizvi)