Python Lesson 19: OOP Basics

Object-Oriented Programming (OOP) is a way to organize code around “objects” — things that have data (attributes) and behaviors (methods). It makes large programs easier to manage.

The Core Idea

# In real life, a Dog has:
# Attributes: name, breed, age
# Behaviors: bark, eat, sleep

# In Python, we model this as a Class:
class Dog:
    def __init__(self, name, breed, age):
        self.name = name      # attribute
        self.breed = breed    # attribute
        self.age = age        # attribute
    
    def bark(self):           # method (behavior)
        print(f"{self.name} says: Woof!")
    
    def describe(self):       # method
        print(f"{self.name} is a {self.age}-year-old {self.breed}")

Creating Objects (Instances)

# Create objects from the class
rex = Dog("Rex", "German Shepherd", 3)
bella = Dog("Bella", "Labrador", 5)

# Access attributes
print(rex.name)    # Rex
print(bella.age)   # 5

# Call methods
rex.bark()         # Rex says: Woof!
bella.describe()   # Bella is a 5-year-old Labrador

Key Concepts

# Class — the blueprint/template
# Object (Instance) — built from the blueprint
# Attribute — data stored inside an object (self.name)
# Method — function that belongs to an object
# self — refers to the current object
# __init__ — the constructor, runs when creating an object

# You can have many objects from one class:
dog1 = Dog("Max", "Poodle", 2)
dog2 = Dog("Luna", "Husky", 4)
dog3 = Dog("Charlie", "Beagle", 1)