CHAPTER 20 — Final Project: Your First Complete Python Application

[Leejohnston]

Chapter 20 — Final Project: Your First Complete Python Application
This is your capstone. You’ll build a structured, multi-file Python application with real features, clean organisation, and user interaction — just like real software engineers do.

This final chapter brings all skills together:
• variables 
• loops 
• functions 
• modules 
• classes 
• file handling 
• data persistence 
• input validation 
• project architecture 

By the end, you will have:
A complete, professional-looking Python program.

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20.1 What You’re Building

THE PERSONAL TASK MANAGER

A command-line app where users can:

• add tasks 
• list tasks 
• mark tasks as done 
• delete tasks 
• auto-save everything to a JSON file 
• load tasks when the program starts 
• structured cleanly across multiple files 

It behaves like a real utility tool — small, neat, and genuinely useful.

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20.2 Project Structure

Create a folder:

task_manager/

Inside, create these files:

Code:

task_manager/
    main.py
    tasks.py
    storage.py
    menu.py
    tasks.json

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20.3 The Data Model (tasks.py)

Code:

class Task:
    def __init__(self, text, done=False):
        self.text = text
        self.done = done

    def mark_done(self):
        self.done = True

    def to_dict(self):
        return {"text": self.text, "done": self.done}

    @staticmethod
    def from_dict(data):
        return Task(data["text"], data["done"])

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20.4 File Storage System (storage.py)

Code:

import json
from tasks import Task

FILENAME = "tasks.json"

def load_tasks():
    try:
        with open(FILENAME, "r") as f:
            data = json.load(f)
            return [Task.from_dict(item) for item in data]
    except FileNotFoundError:
        return []

def save_tasks(tasks):
    with open(FILENAME, "w") as f:
        json.dump([t.to_dict() for t in tasks], f, indent=2)

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20.5 The Menu System (menu.py)

Code:

def show_menu():
    print("\n=== TASK MANAGER ===")
    print("1. View tasks")
    print("2. Add task")
    print("3. Complete task")
    print("4. Delete task")
    print("5. Exit")
    return input("> ")

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20.6 Main Program (main.py)

Code:

from tasks import Task
from storage import load_tasks, save_tasks
from menu import show_menu

tasks = load_tasks()

while True:
    choice = show_menu()

    if choice == "1":
        print("\n--- TASK LIST ---")
        if not tasks:
            print("No tasks yet.")
        for i, t in enumerate(tasks):
            status = "✓" if t.done else "✗"
            print(f"{i+1}. [{status}] {t.text}")

    elif choice == "2":
        text = input("Enter new task: ").strip()
        if text:
            tasks.append(Task(text))
            save_tasks(tasks)
            print("Task added.")

    elif choice == "3":
        num = int(input("Mark which task as done? "))
        if 1 <= num <= len(tasks):
            tasks[num-1].mark_done()
            save_tasks(tasks)
            print("Task completed.")

    elif choice == "4":
        num = int(input("Delete which task? "))
        if 1 <= num <= len(tasks):
            tasks.pop(num-1)
            save_tasks(tasks)
            print("Task deleted.")

    elif choice == "5":
        print("Goodbye!")
        break

    else:
        print("Invalid option.")

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20.7 Optional Upgrades

Try adding:

• deadlines 
• categories 
• coloured output 
• priority rankings 
• sorting features 
• search system 
• export tasks to text file 
• encryption (advanced) 

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20.8 Summary — You’ve Built Real Software

In this final project, you:

• wrote multi-file code 
• used classes & objects 
• handled persistent data 
• designed a menu system 
• used JSON for storage 
• built an actual working app 

You now have the skills to:
• write tools 
• build games 
• analyse data 
• automate tasks 
• prepare for GUI & web apps 

You have completed:
Beginner’s Guide to Coding — Python From Zero to Skill 
Your next step is the Intermediate Python course.

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Written and Compiled by Lee Johnston — Founder of The Lumin Archive