Object-Oriented Programming (OOP)

Since you want the "big picture" of how everything fits together, let's combine the blueprint (Classes) and the philosophy (OOP) into one master topic.

Topic 16: Object-Oriented Programming (OOP) & Classes

In languages like C, you focus on functions (doing things). In Python, you focus on objects (things that have data and can do things). OOP allows you to model real-world entities in your code.

1. The Blueprint: The Class

A Class is a template or blueprint. For example, a "Car" class defines that every car has a color, a brand, and a speed.

2. The Instance: The Object

An Object is a specific car built from that blueprint—like "Arjun’s Red Tesla."

3. Key Components of a Class

• __init__ (The Constructor): A special method that initializes an object's attributes when it is created.

• self: A reference to the current instance of the class. It’s how the object talks to itself.

• Attributes: Variables that belong to the object (e.g., color, name).

• Methods: Functions that belong to the object (e.g., drive(), stop()).

class Smartphone:
    # Constructor: Runs when a new phone is "born"
    def __init__(self, brand, model, battery_level=100):
        self.brand = brand          # Attribute
        self.model = model          # Attribute
        self.battery = battery_level # Attribute

    # Method: A behavior the phone can do
    def make_call(self, number):
        if self.battery > 5:
            print(f"Calling {number} from my {self.model}...")
            self.battery -= 5
        else:
            print("Battery too low!")

# Creating objects (Instances)
my_phone = Smartphone("Apple", "iPhone 15")
your_phone = Smartphone("Samsung", "Galaxy S24", 20)

# Accessing attributes and methods
print(my_phone.brand)        # Output: Apple
your_phone.make_call("911")  # Output: Calling 911 from my Galaxy S24...