__init__ in Python

April 15, 2021

__init__ in Python 

Whenever we listen class, object or Opps one thing comes to our mind is Constructor if we know basic of c++. In this article, we will discuss __init__ in Python, its usages and many more things. If you are familiar with c++, you might have the idea of constructor, __init__ method is the constructor in python.

Let’s understand the function of __init__ in Python.

features of __init__ in Python
Function of  __init__ 
  • The __init__ method is similar to constructors in c++ and Java.
  • Constructors are used to initialize the object’s state.
  • The task of constructors is to initialize(assign values) to the data members of the class when an object of class is created. 

Synatx: 

class ClassName:
  def __init__( self , variables...):
    ##body

Code #1:

#python Program
#Rishikesh 
class Prepster: 
    def __init__(self, name , userid,password): ##constructor 
        self.name=name  ## assigning values to variables 
        self.userid=userid 
        self.password=password
 
ob1=Prepster(‘rishikesh’,‘Abc’,‘abc@123’) ##object 
print(ob1.name)

Output: 

rishikesh

Let’s understand this code:

  • a prepster  name “rishikesh” is created. While creating a prepster, “rishikesh”, “Userid”, “password” is passed as an argument, this argument will be passed to the __init__ method to initialize the object.
  • The keyword self represents the instance of a class and binds the attributes with the given arguments.
__init__ in Python

Code #2 (init with inheritance):

#python Program
#Rishikesh 

 
class PrepInsta:
    def __init__(self,name):
        self.name=name 
        print(‘You are in Parent class’)
class Prepster(PrepInsta): 
    def __init__(self, name): ##constructor 
        PrepInsta.__init__(self,name) 
        print(‘You are in Child Class’)
        self.name=name  ## assigning values to variables

ob1=Prepster(‘rishikesh’) ##object 

Output:

You are in Parent class
You are in Child Class
  • Here the parent class constructor is called first, but in Python, it is not compulsory that parent class constructor will always be called first. The order in which the __init__ method is called for a parent or a child class can be modified. This can simply be done by calling the parent class constructor after the body of child class constructor.
#python Program
#Rishikesh 

 
class PrepInsta:
    def __init__(self,name):
        self.name=name 
        print(‘You are in Parent class’)
class Prepster(PrepInsta): 
    def __init__(self, name): ##constructor 
         
        print(‘You are in Child Class’)
        self.name=name  ## assigning values to variables 
        PrepInsta.__init__(self,name)

ob1=Prepster(‘rishikesh’) ##object 

Output: 

You are in Child Class
You are in Parent class