CONSTRUCTOR IN PYTHON 2022

CONSTRUCTOR:

Constructors logics are executed only when object is created.

Ex-1:

              class Myclass():

                def __init__(self):

                      print(“Hi”)

                def wish (self):

                       print(“Hello”)

              c=Myclass()    #Hi

              c.wish()     #Hello

• If global variables name and local variables name is same then we represent global variable with global ().

Ex-1:

a=100

b=200

class Myclass() :

  def wish (self, name):

    a,b=10,20

    print(a+b)

    print(name)

    print(globals()[‘a’]+globals()[‘b])

c=Myclass()

c.wish(“Purna”)   #30

                  #Purna

                  #300

Ex-2:

class Myclass():

   def __init__(self,a,b):

       self.a=a

       self.b=b

   def add(self)

       print(a+b)

c=Myclass(10,20)

c.add()

C=Myclass(30,40)

c1.add()

                                            ADVANTAGES OF CONSTRUCTOR:

To execute some logics before execution of the method, We can write that logics in constructors.

To initialize instance variables.

Ex-1:

class Myclass() :

 def __init__(self,a,b,c):

   self.a=a

   self.b=b

   self.c=c

 def add(self):

    print(9”name={}/n Id={}/n Salary={}”.format(self.a, self.b, self.c)

c=Myclass(“Purna”,111, 10000)

c.add()

c1=Myclass(“Raju”,222,20000)

c1.add()

Ex-2:

class Myclass():

  @staticmethod

  def wish():

    print(“good morning”)

  def disp(self):

    print(“hello”)

c=Myclass()

c.disp()

Myclass.wish()

• Whenever print the reference variable, controller internally calls underscore undersore(__) str method.
• Pointer contains address of another variable.

Ex-1:

class Myclass();

  def wish():

     print(“hello”)

c=Myclass()

c.wish()

print(c )

Ex-2:

class  Myclass():

    def __str__(self):

         return”Purna”

c=Myclass()

print( c)

Ex-3:

class Myclass():

   def __str__(self)

          print(“hello”)

          return “Hai”

c=Myclass()

print( c) 

• Write a program to print employee details using reference variable.

class Myclass():

   def __init__(self,a,b,c):

        self.a=a

        self.b=b

         self.c=c

    def __str__(self):

          return “name={}/n  id={}/n Saalary={}” .fomat(self.a,self.b,self.c)

c=Myclass(“Purna”,111,40000)

print(c)

c1=Myclass(“Hari”,222,20000)

print(c1)

Ex-1:

class Myclass():

     def __del__(self):

          print(“destroy”)

c=Myclass()

del c

Ex-2:

class Myclass():

   def __del__(self):

      print(“destroy”)

c=Myclass()

c1=Myclass()

del c

del c1

• If one object with multiple references whenever reference count zero then only del method will be executed.

Ex-3:

class Myclass():

   def __del__(self):

       print(“destroy”)

c=Myclass()

c1=c

c2=c

del c