OOPs Concepts in nutshell

Features of OOP

  • Abstraction : Act of hiding unnecessary information and showing relevant informaion.

    Real life example

      [Watching TV and setup procedures are in TV manual. How TV internally works is part of data abstraction.]

  • Encapsulation : Wrapping up of data and operations in single unit.

    Real life example

      [Consider an ATM machine , it has both money (data) and ATM services (functions) integarted to ATM machine.]

  • Inheritance : Act of inheriting features from parent class.

    Real life example

      [Grand parents -> Parents -> us -> our children 😃 ]

  • Polymorphism : Process of representing one form in multiple forms

    Real life example

      [Consider behaiviour of a person : mother/father to their childern , wife/husband to their spouse , daughter/son to their parents , employee to a company , customer to a shopkeeper ,etc. At the end , its just a person]

  • Object : Instance of class . It is a bundle of data and behaiviour

  • Class : Its a blueprint of creating objects

Simple Class and Object implementation in Python

class Startrek:
    shipname="StarShip Enterprise"
    
    # __init__ is a constructor which initializes the value | self is an instance - it can be named anything
    def __init__(self,name,dept,rank):
        self.name = name
        self.dept = dept
        self.rank = rank
    
    # method to print the data 
    def printfeatures(self):
        return f"Name - {self.name} | Dept - {self.dept} | Rank - {self.rank}"

# initiatizing objects to class Startrek
emp1=Startrek("Picard","Starship","Captain")
emp2=Startrek("Will Ryker","Starship","1st Officer")
emp3=Startrek("Daenna Troi","Starship","Counselor")
emp4=Startrek("Worf","Security","Lieutenant")
emp5=Startrek("La Forge","Engineering","Lieutenant")
emp6=Startrek("Data","Engineering","Commander")
emp7=Startrek("Crusher","Medical","Chief Medical officer")

# call the menthod from the class
print(emp1.printfeatures())
print(emp2.printfeatures())
print(emp3.printfeatures())
print(emp4.printfeatures())
print(emp5.printfeatures())
print(emp6.printfeatures())
print(emp7.printfeatures())


>>
Name - Picard | Dept - Starship | Rank - Captain
Name - Will Ryker | Dept - Starship | Rank - 1st Officer
Name - Daenna Troi | Dept - Starship | Rank - Counselor
Name - Worf | Dept - Security | Rank - Lieutenant
Name - La Forge | Dept - Engineering | Rank - Lieutenant
Name - Data | Dept - Engineering | Rank - Commander
Name - Crusher | Dept - Medical | Rank - Chief Medical officer

Example 2 : 1st Replace and then reverse the list

class Numset:
    
    def replt(self,numarr,pos,value):
        numarr[pos] = value
        #print(numarr)
        rnumarr = self.revrs(numarr)
        return rnumarr
    
    def revrs(self,numarr):
        numarr.reverse()
        return numarr
    
numarr = [1,2,3,4,5,6,7,8,9]

num1=Numset()
print ("list before replace and reverse : ", numarr)
lst = num1.replt(numarr,2,10)
print ("list after replace and reverse : ", lst)

>>>
list before replace and reverse :  [1, 2, 3, 4, 5, 6, 7, 8, 9]
list after replace and reverse :  [9, 8, 7, 6, 5, 4, 10, 2, 1]

Inheritance in Python


class Starship: 
       
    # Constructor 
    def __init__(self, name): 
        self.name = name 
   
    # To get name 
    def getName(self): 
        return self.name 
   
    # To check if this person is working in Starship
    def isWorking(self): 
        return False
   
   
# Inherited or Subclass (Note Starship in bracket) 
class Employee(Starship): 
   
    def isWorking(self): 
        return True
    
emp = Starship("Romulan")  # An Object of Starship 
print(emp.getName(), emp.isWorking()) 
   
emp = Employee("Picard") # An Object of Employee 
print(emp.getName(), emp.isWorking()) 


>>
Romulan False
Picard True