Object Oriented Programming by Using Python

Object-Oriented Programming in Python
Classes, Objects, Inheritance, Polymorphism More
Madhusudhana Rao Baswani
Python Training Series
July 23, 2025

Agenda
1 OOP Basics
2 Core Terminology
3 Classes & Objects
4 Constructors & Methods
5 Encapsulation
6 Inheritance
7 Polymorphism
8 Abstraction
Madhusudhana Rao Baswani (Python Training Series) Object-Oriented Programming in Python July 23, 2025 2 / 17

What is OOP?
Programming style that bundles data & operations
into objects.
Promotes modular, reusable, and maintainable code.
Key pillars: Encapsulation, Inheritance, Polymorphism, and Abstraction.

Why OOP in Python?
Everything in Python is an object — even functions and types.
Easy syntax for defining classes and methods.
Supports dynamic typing and duck typing for flexible design.

Glossary
Class Blueprint for creating objects.
Object Instance of a class containing state & behavior.
Data Member Variable defined in a class (instance or static).
Method Function defined inside a class.
Instance/Static & Local Vars Object-level, class-level, and method-scope variables.

Defining a Class
class Student:
""" Represents a student entity """
school = "Leela High" # static var
def __init__(self , name , marks):
self.name = name # instance vars
self.marks = marks

Instantiating Objects
s1 = Student("Kajal", 90)
s2 = Student("Rohith", 85)
print(s1.name , s1.marks)

Constructor
i nit
Automatically invoked during object creation.
First parameter self points to the current object.
Used to initialize instance variables.

Method Types
Type First Param
Instance Method self (object)
Class Method cls (class)
Static Method none

Example: Class & Static Methods
class MathDemo:
factor = 2 # static variable
@classmethod
def double(cls , x):
return x * cls.factor # uses class var
@staticmethod
def add(x, y):
return x + y

Private Attributes
class Car:
def __init__(self):
self.__maxspeed = 200 # private
def drive(self):
print(self.__maxspeed)
Access via name-mangling: obj._Car__maxspeed

Single Inheritance
class Animal:
def eat(self):
print(’Eating ’)
class Dog(Animal):
def bark(self):
print(’Barking ’)
d = Dog(); d.eat(); d.bark()

Types of Inheritance
Single
Multiple
Multilevel
Hierarchical
Hybrid

Compile-time vs Runtime
Operator Overloading: + works for numbers and strings.
Method Overloading: Not natively supported; emulate with default/args.
Method Overriding: Redefine a parent method in child class.

Operator Overloading Example
class Book:
def __init__(self , pages):
self.pages = pages
def __add__(self , other):
return self.pages + other.pages
print(Book (100) + Book (200)) # 300

Abstract Base Class
from abc import ABC , abstractmethod
class Shape(ABC):
@abstractmethod
def area(self):
pass

Questions?
Thank You!

Object Oriented Programming by Using Python

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