Constructor in Python

By Hussain Quadri

In this tutorial, we will learn about Constructor in Python.

In Object-oriented Programming, a special kind of method is used to instantiate an object.
It initializes values to the data members of the class whenever an object is created.
In other languages like C++, and Java the constructor has the same name as the method. However, in Python constructors in Python are independent of the class name and has their own name. The method __init__() is the constructor in Python and is called when an object is created.
The purpose of defining a constructor is, it provides state and uniqueness to the object.
In Python, a constructor is invoked automatically when we create an object.

Syntax of a constructor :

def __init__(self):
  #body

Creating a constructor :
We need to define a method called __init__() inside our class.
This method takes an argument known as self. In addition to it, we can define many parameters.

Example Code:

class Hello:
def __init__(self):
print("Hey, Coder!")
h1=Hello()

Output:

Hey, Coder!

In the example we can see that, constructor is called when the object is created.

Different types of constructor:
There are three types of constructors, they are
1)Parameterized Constructor
This type of constructor has multiple parameters along with self keyword.

Example:

class Hello:
    def __init__(self,name):
    self.name=name

print("hey",self.name)
h1= Hello("JOHN DOE")

Output :

Hey, JOHN DOE

2)Non-parameterized constructor
This type of constructor does not have any other argument, it just has self as an argument.

Example:

class Hello:
    def __init__(self)
    print("Hey, coder")
h1=Hello()

Output: 

Hey, coder

3)Default constructor
When we don’t include the constructor in the class, then it becomes default constructor. It does not do any tasks but initializes the objects .

Example:

class Hello:
    name="John doe"
    def show(self):
        print("My name is ", self.name)
h1= Hello()
h1.show()

Output : 

My name is John doe