Object Oriented Programming

Object Oriented Programming

  • Python, a popular programming language, offers a powerful feature called object-oriented programming (OOP).

  • This approach allows developers to organize their code in a way that makes it easier to understand and reuse.

  • Central to OOP in Python are classes, which act as blueprints for creating objects with shared characteristics and behaviors.


  • They are abstract and blueprint only. For example, Let's imagine a map of your house before you construct it is class.

  • One class can have many objects like we can make multiple houses with the help of the same map.

      class Classname:
          #your variables and functions


  • When the house is constructed from it then it is considered an object which exists and is real.

  • Similarly, various features of house such as color, furniture, number of rooms, etc are also objects.

      object_name = Classname()

Some examples to create classes and objects :

#creating class
class Number:
    def sum(self):
        return self.a + self.b

obj = Number()
obj.a = 10
obj.b = 10
s = obj.sum()#calling sum() with 
print(s) # Object = 20

Creating a class with constructor(__init__())

class Map:
    #instance method because it is bound to instance of class
    category = 'house_category'
    def __init__(self, color, num_rooms, area):
        #declaring instance variable
        self.color = color
        self.num_rooms = num_rooms
        self.area = area

# Creating different objects for the House class
house1 = Map("Green", 10, 2500)#object1
house2 = Map("Orange", 2, 1000)#object3

print(house1.color) # Output = Green
print(house2.num_rooms) # Output = 2

__init__() constructor

  • __init__ method is the constructor in Python which is automatically called at the time of object creation.

  • __init__ is the instance method because it is bound to the instance of the class.

  • Various variable inside this method is instance variable because it is associated with the object(self)

  • category variable or attributes outside init consctuctor is class variable.

Self keyword

  • self parameter is automatically passed as the first argument whenever the method is called.

  • By convention, it is named self, although you can technically use any valid variable name in its place.

  • self is the object in python.

  • self parameter allows you to access and manipulate the instance's attributes and call other instance methods within the class. For instance, self.attribute_name or self.function_name()