Build a Personal Finance Tracker - Day 2: Adding Classes

Level: Beginner

Projects in this week’s series:

This week, we progressively build a finance tracker with Python.

• Day 1: Basic with Functions

• Day 2: Object-Oriented (Today)

• Day 3: With CSV Storage

• Day 4: With GUI

View All Projects This Week

Today’s Project

Yesterday we built our MVP — a working expense tracker using functions. Today we’re learning a crucial real-world skill: refactoring.

As your codebase grows, you need better organization. That’s where Object-Oriented Programming comes in. We’ll transform our function-based tracker into a class-based system, making it more scalable and professional.

This is exactly what happens in real development: you start with working code, then improve the architecture when you need more structure.

👉 TIP: Click the “Project Code Timeline” button at the bottom of this page to view and compare today’s code solution with yesterday’s code and see a web interface that shows how the code has evolved (here is a snapshot):

Today’s Challenge: Refactor with Classes

Today we’re taking the same functionality and organizing it with classes. We’ll create an Expense class to represent individual expenses and an ExpenseTracker class to manage the collection and operations.

Why refactor? Because as we add more features (budgets tomorrow, web interface Thursday), having organized classes will make our code much easier to extend and maintain.

Project Task

Create a class-based expense tracker that:

• Uses an Expense class to represent individual expenses

• Uses an ExpenseTracker class to manage all expenses

• Stores expense data as object attributes

• Implements methods for adding, viewing, and analyzing expenses

• Maintains the same functionality as Day 1 but with better structure

• Demonstrates how classes encapsulate data and behavior together

This project gives you hands-on practice with class creation, object instances, methods, and understanding when and why to refactor code — essential skills for professional development.

Expected Output

Coming Tomorrow

Tomorrow we’ll add CSV storage and budget limits — you’ll see how our class-based design makes adding these features much easier than it would have been with just functions!

View Code Evolution

Compare today’s solution with earlier versions and see how the code evolves.