Python Classes And Objects

Python is an Object-Oriented Programming Language which means almost everything in Python are based on the concept of objects that can contain data in the form of fields and properties and code in the form of methods.

Class

A class is a blueprint for creating objects.

Syntax

class <ClassName>:

Create Python Class

The class keyword is used to create a class in Python.

Example

Create a class Dog with a single String type property color with value Brown:

class Dog:
    color = "Brown"
  

Create Python Object

An object in Python, is created from a class.

Example

Create an object of the Dog class:

class Dog:
    color = "Brown"

dog =  Dog()
print(dog.color)
  

Output

The __init__() Function / Class Constructor

The __init__() function is a built-in Python function. Every class in Python has the __init__() function and is executed while creating an object of a class.

The __init__() function is used as a constructor of the class to initialize properties of the class or to perform other operations that needs to be executed while creating an object.

Example

class Customer:
    def __init__(self, firstname, lastname, age):
        self.firstname = firstname
        self.lastname =  lastname
        self.age = age

customer = Customer("Danny", "Charm", 26)
print(customer.firstname)
print(customer.lastname)
print(customer.age)
  

Output

The self Parameter

The self parameter is used to represent the current instance of the class which helps to access properties and methods of the class.

Object Methods

A method is a block of code or function that belongs to an object. Methods can only be called after creating objects.

Create Object Methods

Object methods are created inside the body of a class using the def keyword followed by the method name and parenthesis as shown in the example below:

Example

class Calculator:
    
    def add(self, x, y):
        result = x + y
        return result

    def substract(self, x, y):
        result = x - y
        return result

    def multiply(self, x, y):
        result = x * y
        return result

    def divide(self, x, y):
        result = x / y
        return result

cal = Calculator()
a = cal.add(115,6)
b = cal.substract(190, 100)
c = cal.multiply(5, 5)
d = cal.divide(100, 16)

print("Addition is " + str(a))
print("Substraction is " + str(b))
print("Multiplication is " + str(c))
print("Division is " + str(d))
  

Output