Section Overview

This section introduces you to the basics of object-oriented programming (OOP) in Python. You’ll learn how to create your own classes to model real-world things and organize your code into objects.

By the end of this section, you should be able to:

• Understand what classes and objects are
• Define a class with attributes and methods
• Create objects (instances) of a class
• Use object properties and call methods

Lesson 1: What is a Class?

A class is like a blueprint for creating objects. It defines attributes (data) and methods (functions) that belong to the objects.

Example:

class Dog:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def bark(self):
        print(f"{self.name} says woof!")

Lesson 2: Creating Objects

You create an object (instance) by calling the class name like a function:

my_dog = Dog("Buddy", 3)
my_dog.bark()

Output:

Buddy says woof!

Lesson 3: The __init__ Method

__init__ is a special method called a constructor. It runs automatically when a new object is created and initializes the object’s attributes.

Lesson 4: Accessing Attributes and Methods

You access attributes and methods using dot notation:

print(my_dog.name)  # Outputs: Buddy print(my_dog.age)   # Outputs: 3
my_dog.bark()       # Calls the bark method 

Quiz: Check Your Understanding

1. What is an object?
Answer: An instance of a class representing a real-world thing.

2. What special method is called when an object is created?
Answer: __init__

3. How do you define a method inside a class?
Answer: By defining a function with def inside the class.

4. What does self represent inside a class method?
Answer: The instance (object) itself.

Practice Exercise: Create a Car Class

Write a class called Car that has:

• Attributes: make, model, and year
• A method display_info() that prints out the car’s details

Then create two Car objects and call display_info() on each.

Starter code:

class Car:
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year

    def display_info(self):
        print(f"{self.year} {self.make} {self.model}")

car1 = Car("Toyota", "Camry", 2020)
car2 = Car("Honda", "Accord", 2018)

car1.display_info()
car2.display_info()