Python OOP Fundamentals — Building Code Like a Pro

“Functions are good. Objects are better when things get complex.”

🟡 Why OOP in DSA?

Most DSA problems can be solved with functions and loops. But when problems involve custom data structures (like Linked Lists, Trees, Graphs) — you need Objects & Classes.
OOP (Object-Oriented Programming) helps you model real-world entities in code.

🔹 1. What is Object-Oriented Programming (OOP)?

OOP is a coding style where we structure code around objects — entities that hold data (attributes) and behaviors (methods).

Think of a "Car":

Attributes: color, brand, speed
Methods: accelerate(), brake(), honk()

🔹 2. Class & Object in Python

➤ Define a Class:

class Car:
    # Constructor
    def __init__(self, brand, color):
        self.brand = brand  # attribute
        self.color = color  # attribute

    # Method
    def honk(self):
        print(f"{self.brand} says Beep Beep!")

➤ Create an Object:

my_car = Car("Tesla", "Red")
print(my_car.brand)  # Output: Tesla
print(my_car.color)  # Output: Red

my_car.honk()  # Output: Tesla says Beep Beep!

Breakdown:

class Car: → Blueprint of an object
__init__ → Constructor that initializes object’s data
self → Refers to the current object instance
Attributes like brand and color are tied to self
honk() is a method that belongs to the object

🔹 3. OOP Concepts You Need to Know (For DSA & Life)

➤ Encapsulation (Data hiding with Classes)

Group related data and functions together.

class BankAccount:
    def __init__(self, balance):
        self.__balance = balance  # private attribute

    def deposit(self, amount):
        self.__balance += amount

    def get_balance(self):
        return self.__balance

__balance is private (name mangled)
Access via methods like get_balance()

➤ Inheritance (Reusing Classes)

Child classes inherit properties from parent classes.

class Vehicle:
    def __init__(self, brand):
        self.brand = brand

    def drive(self):
        print(f"{self.brand} is moving...")

class Car(Vehicle):
    def honk(self):
        print(f"{self.brand} says Beep!")

my_car = Car("Toyota")
my_car.drive()  # From parent class
my_car.honk()   # From child class

➤ Polymorphism (Same Method, Different Behaviors)

class Dog:
    def speak(self):
        print("Woof")

class Cat:
    def speak(self):
        print("Meow")

def animal_sound(animal):
    animal.speak()

dog = Dog()
cat = Cat()

animal_sound(dog)  # Output: Woof
animal_sound(cat)  # Output: Meow

➤ Abstraction (Optional, Advanced)

Hiding internal details and showing only essential features.

from abc import ABC, abstractmethod

class Shape(ABC):
    @abstractmethod
    def area(self):
        pass

class Circle(Shape):
    def __init__(self, radius):
        self.radius = radius

    def area(self):
        return 3.14 * self.radius * self.radius

🟢 Day 2 Takeaways:

✅ I can now build custom Data Structures using Classes
✅ I understand how attributes & methods shape objects
✅ I know how to reuse and extend code using inheritance
✅ I’m not scared of OOP jargon anymore.

#DSA #8WeekGrind #Day2 #PythonOOP #LearningInPublic #CodeGrind #DSAFundamentals

DSA: The 8-Week Grind — Day 2