Constructor in Python

 

Python Constructor

A constructor is a special method used to initialize instance variable

• Name of constructor must be _ _ init _ _()

 #program to define a constructor

 class Employee_data :
         def __init__(self):
                 print("This is a Python Constructor")

• It is called at object creation time.

 #program to define a constructor

 class Employee_data :
         def __init__(self):
                 print("This is a Python Constructor, called at Object creation Time")

 Emp_data = Employee_data()

 #Output

 This is a Python Constructor, called at Object creation Time

• Constructor is called once for every object.

 #program to define a constructor

 class Employee_data :
         def __init__(self):
                 print("This is a Python Constructor, called at Object creation Time")

 Emp_data_1 = Employee_data()
 Emp_data_2 = Employee_data()

 #Output

 This is a Python Constructor, called at Object creation Time
 This is a Python Constructor, called at Object creation Time

• Constructor takes "self" as a default parameter.

 #program to define a constructor

 class Employee_data :
         def __init__(self):
                 self.a = 10
                 self.b = 5
                 print("This is a Python Constructor, called at Object creation Time")

         def display(self):
                 print("a :", self.a)
                 print("b :", self.b)

 Emp_data = Employee_data()
 Emp_data.display()

 #Output

 This is a Python Constructor, called at Object creation Time
 a : 10
 b : 5

• Constructors are of 2 type

• Default Constructor (Non-Parameterized)

                    It holds common value for every object 

 #program to define a constructor

 class Employee_data :
         def __init__(self):
                 self.name = "Techno Xpresss"
                 self.website = "www.salahtutorials.com"
                 print("This is a Python Constructor, called at Object creation Time")

         def display(self):
                 print("Name :", self.name)
                 print("website :", self.website)

 Emp_data_1 = Employee_data()
 Emp_data_2 = Employee_data()
 Emp_data_1.display()
 Emp_data_2.display()

 #Output

 This is a Python Constructor, called at Object creation Time
 This is a Python Constructor, called at Object creation Time
 Name : Techno Xpresss
 website : www.salahtutorials.com
 Name : Techno Xpresss
website : www.salahtutorials.com

• Parameterized Constructor

                    It holds unique value for every object

 #program to define a constructor

 class Employee_data :
         def __init__(self, name):   # constructor accepts value as parameter
                 self.name = name
                 self.website = "www.salahtutorials.com"
                 print("This is a Python Constructor, called at Object creation Time")

         def display(self):
                 print("Name :", self.name)
                 print("website :", self.website)

 Emp_data_1 = Employee_data("Techno Xpresss")   # passing value to constructor while object creator
 Emp_data_2 = Employee_data("Er M S Dandyan")   # passing value to constructor while object creator
 Emp_data_1.display()
 Emp_data_2.display()

 #Output

 This is a Python Constructor, called at Object creation Time
 This is a Python Constructor, called at Object creation Time
 Name : Techno Xpresss
 website : www.salahtutorials.com
 Name : Er M S Dandyan
 website : www.salahtutorials.com