Introduction to Object-Oriented Programming

Object-Oriented Programming is a way of writing programs by using objects. Think of objects as things in the real world. For example, a car, a dog, or even a smartphone can be objects. Each object has:

• Attributes (things it has): A car has a color, brand, and speed.
• Behaviors (things it does): A car can start, stop, and accelerate.

In Python, we create objects using classes.

Key concepts of OOP

• Class: A blueprint or template for creating objects. For example, the blueprint of a car.
• Object: An instance of a class. For example, your specific car, a red Toyota.
• Attributes: Variables that store information about the object. For example, the car's color is "red".
• Methods: Functions that define behaviors for an object. For example, start() makes the car start.
• Encapsulation: Bundling the data (attributes) and methods inside a class.
• Inheritance: A way to create a new class from an existing class. For example, a "SportsCar" can inherit from a general "Car" class.
• Polymorphism: Objects can share the same method name but behave differently based on their class.

Let's see an example

Imagine we want to create a program to manage pets:

# Define a class
class Dog:
    # Constructor method: Defines how to create a Dog object
    def __init__(self, name, age):
        self.name = name  # Attribute: Dog's name
        self.age = age    # Attribute: Dog's age

    # Method: A behavior of the dog
    def bark(self):
        return f"{self.name} says Woof!"

    def birthday(self):
        self.age += 1
        return f"{self.name} is now {self.age} years old!"

# Create objects (instances of Dog)
dog1 = Dog("Buddy", 3)  # A dog named Buddy, 3 years old
dog2 = Dog("Charlie", 5)  # A dog named Charlie, 5 years old

# Access attributes and call methods
print(dog1.name)  # Output: Buddy
print(dog1.bark())  # Output: Buddy says Woof!
print(dog1.birthday())  # Output: Buddy is now 4 years old!

Why use OOP?

• Reusability: Create reusable blueprints (classes) and avoid rewriting code.
• Organization: Bundle data and behaviors together, making your program easier to manage.
• Scalability: Easily add new features by extending classes.