Introduction to Object-Oriented Programming

Learning Objectives: After this lesson, you'll understand the fundamentals of OOP in Python - classes, objects, attributes, and methods - and learn to build your first Python classes with proper encapsulation.

What is Object-Oriented Programming?

Object-Oriented Programming (OOP) is a programming paradigm that organizes code around objects - entities that contain both data (attributes) and functions (methods) that operate on that data.

Think of objects like real-world entities:

• A car has properties (color, model, speed) and behaviors (start, stop, accelerate)
• A bank account has properties (balance, owner) and behaviors (deposit, withdraw, check_balance)
• A student has properties (name, grades) and behaviors (study, take_exam, calculate_gpa)

Classes and Objects

A class is a blueprint for creating objects. An object is an instance of a class.

Interactive OOP Playground

Now let's visualize how OOP works with an interactive playground! Create objects, call methods, and see how each object maintains its own state:

Class Anatomy

Let's break down the parts of a class:

<OOPInheritanceTree initialClasses={[ { "id": "bankaccount", "name": "BankAccount", "methods": ["init", "deposit", "withdraw", "get_balance"], "attributes": ["owner", "balance"], "level": 0 } ]} />

Instance vs Class Variables

Understanding the difference between instance and class variables:

Methods and Self

The self parameter is crucial in Python classes:

Encapsulation and Privacy

Python uses naming conventions to indicate privacy:

Special Methods (Magic Methods)

Python classes can define special methods that enable built-in operations:

Practical Examples

Example 1: Student Management System

Example 2: Library Management System

Key Takeaways

✅ Classes are blueprints for creating objects with attributes and methods
✅ Objects are instances of classes with their own data
✅ init method initializes new objects (constructor)
✅ self parameter refers to the current instance
✅ Instance variables are unique to each object
✅ Class variables are shared by all instances
✅ Encapsulation uses naming conventions (_protected, __private)
✅ Special methods enable built-in operations (__str__, __len__, etc.)

Next Steps

In the next lesson, we'll learn about error handling and debugging - how to handle errors gracefully with try-except blocks, understand common exceptions, and master debugging techniques to make your code more robust.

Ready to make your code bulletproof? The next lesson will teach you professional error handling techniques!