Instance Variable in Python

 

Python Class Instance Variable

• Variables defined inside a Class Method with "self" as a keyword.

Example :

 #program to define instance variable

 class Team :
     team_name = "INDIA"                #static Variable

     def assign_team_member(self):
         self.cricket_team = 11         # instance variable, defined with keyword self
         self.kabaddi_team = 7          # instance variable, defined with keyword self

• They get memory at object creation time, not at class loading time. so without creating object, instance variables can not be called.

Example : 

 #program 

 class Team :
     team_name = "INDIA"

     def assign_team_member(self):
         self.cricket_team = 11
         self.kabaddi_team = 7

     def display_team_member(self,):
         print("\nno of players in cricket team :", self.cricket_team)
         print("\nno of players in kabaddi team :", self.kabaddi_team)

 print("Team_name : ", Team.team_name)                # calling static variable with class name
 print("assigning value", Team.assign_team_member())  # calling method without creating object

 #Output

 Team_name :  INDIA
 Traceback (most recent call last):
   File "C:/Self_Practice_Er_M_S_Dandyan/Python/Pycharm/xml/main.py", line 15, in <module>
     print("assigning value", Team.assign_team_member())
 TypeError: assign_team_member() missing 1 required positional argument: 'self'

• To call instance variable, we use Object.

Example : 

 #program
  
 class Team :
     team_name = "INDIA"                    # static Variable, will load at class loading time

     def assign_team_member(self):
         self.cricket_team = 11             # Instance variable, will load at object creation time
         self.kabaddi_team = 7              # Instance variable

     def display_team_member(self,):
         print("\nno of players in cricket team :", self.cricket_team)
         print("\nno of players in kabaddi team :", self.kabaddi_team)

 print("Team_name ; ", Team.team_name)

 team_details = Team()
 team_details.assign_team_member()
 team_details.display_team_member()

 #output

 Team_name ;  INDIA

 no of players in cricket team : 11

 no of players in kabaddi team : 7

• They hold unique value for individual Object

Example :

 #program

 class Employee_data :
     company_name = "AETies"

     def assign_employee_data(self, name, id, salary):
         self.emp_name = name
         self.emp_id = id
         self.emp_salary = salary

     def display_employee_data(self,):
         print("\nname :", self.emp_name, end="\t")
         print("id :", self.emp_id, end="\t")
         print("salary :", self.emp_salary, end="\t")
         print("Company : ", Employee_data.company_name)

 emp_1 = Employee_data()
 emp_2 = Employee_data()

 emp_1.assign_employee_data("Techno Xpresss", 101, 25.876)
 emp_2.assign_employee_data("Er M S Dandyan", 102, 28.786)

 emp_1.display_employee_data()
 emp_2.display_employee_data()

 #Output

 name : Techno Xpresss  id : 101   salary : 25.876    Company :  AETies

 name : Er M S Dandyan  id : 102   salary : 28.786    Company :  AETies