OOPs in Python in Hindi (Part -14)

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        OBJECT ORIENTED PROGRAMMING

Python ek object oriented programming language hai, iska mtlb ye hai ki Python mai hr ek chiz object hai. Dekho Oops kafi confusing ho skta hai agar ap longo ko oops kafi gande tarike se padhya gya hai , mai is post ke jariye ap longo ko oops ko bahut assan shabdo mai samjhane ki pori koshish krunga. 

Aayiye oops padhne se pehle kuch terms clear kr lete hai , taki ap longo ko ise padhne mai koi muskil na ho.

Class and object

Class ek design ya blueprint hai. Object ek real thing hai.

Aayiye ise example ki madad se aur clear krte hai jaise Animal ek class hai aur cat , dog , tiger etc ye sb object hai, Animal ek real chiz nhi hai lekin object ek real chiz hai

Ek example aur lete hai jaise bhot longo ke pass iPhone 11 hoga lekin ye design sirf ek baar hi kiya jata hai to ek class ke pass kai object ho skte hai.

Aayiye object ko aur deep se samjhte hai

Jaise...

mylist = [ 3,5,6,7]

to hm yaha kahenge ki mylist ek object hai class list ka , lekin ye jo list class hai ye built in class hai, hm yaha khud ki class bana skte hai jise hm user-defined class kahenge.

Object kya hai ?

Object ek real chiz hai, object ke pass attribute aur behaviour hota hai, attribute is like how we look , what we wear ,basically ise variables kahte hai behaviour hamare action ko define krta hai like walking , talking , sleeping etc. ise hm methods kah skte hai.

Function inside a class is called method

                                                         

User defined class

Class ko create krne ke liye hme class keyword ka use krna padta hai

Example:

---------------------------------------------------------------------------------

#creating a  class

class Computer:

    def config(self):

        print("i5 , 16gb , 1TB")

#creating an object

com1= Computer()

#Calling an object

Computer.config(com1)

Ouptut:

i5 , 16gb , 1TB

#class ko hm create krte hai class keyword ki madad se

#config yaha ek method hai

#com1 name ka hmne ek object create kiya hai

#Aur fir hmne ise call kiya hai , call krte samay hm kr kya rahe hai ki hmne self(argument) mai com1 name ka parameter pass kiya hai

#Self keyword ki madad se hm kisi bhi python class ke attributes aur method ko acess kr skte hai

#It is good programming practice to start the class name with capital letter

#Another way of calling an object

com1.config()

Output:

i5,16gb 1tb

------------------------------------------------------------- 

# Another way of doing this same program

class computer:

    def config(self):

        print("i5,16gb 1tb")

com1 = computer()

com1.config()

Output:

i5,16gb 1tb

------------------------------------------------------------------------------------

                    __init__ Method

init stand for intialization , init method ka use hota hai variable ko intialize krne ke liye , init method ki speciality ye hai ki ise hme call nhi krna padta hai ye automatically call ho jati hai object create krte samay.

Let's take an example

------------------------------------------------------------

 class grow:
    def __init__(self):
        print("in init")
    def config(self):
        print("hello")

com1 = grow()
com1.config()

Output:

in init
hello

#To ap dekh skte hai ki init method ko hame call nhi krna padta , ye automatically call ho jati hai object create krte samay, ye java ke constructor se kafi similar hai.
-----------------------------------------------------------
class Computer:
    def __init__(self, cpu, ram):
        self.cpu = cpu #intializing the value 
        self.ram = ram
    def config(self):
        print(self.cpu , self.ram)

com1 = Computer('i5' ,16)
com2 = Computer('Ryzen 3' ,8)
com1.config()
com2.config()

#Output:
i5 16
Ryzen 3 8

# Self parameter basically hr method ka first parameter hota hai, Self name jruri nhi hai hm koi bhi name use kr skte hai lekin most commanly self use hota hai becoz it increase the code readability
#Self ka use basically variable ko access krne krne ke liye hota hai jo ki us particular class ko belong krte hai.
----------------------------------------------------------
class BadmintonPlayer():
     def __init__(self,aName,aRacket,aShuttle):
        print('I m in Constr...')
        self.name = aName
        self.racket = aRacket
        self.shuttle = aShuttle


sindhu = BadmintonPlayer('Sindhu','Yonex','Yonex')

Output:
I m in Constr...
--------------------------------------------------------------------------------------
class Person():
    def __init__(self,aName):
        print('I m in Constructor')
        self.name = aName
    def eat(self):
        print('Idly')
    def play(self):
        print('Badminton')

        print('or Cricket')
    def exercise(self):
        print('Jogging')

p1 = Person('Sai')

p1.eat()
p1.play()
p1.exercise()
p1.name

Output:
I m in Constructor
Idly
Badminton
or Cricket
Jogging
'Sai'

#p1.name , basically yaha hm attribute ko acess krne ki koshish kr rahe hai isliye hmne yaha parenthesis() nhi lagaya

# har method ki first parameter mai hmne self isliye likha hai kyoki hm us self mai P1 parameter pass kr rahe hai jo ki hamara object hai

#Agar ap self parameter nhi likhoge to at the time of calling ap ko error milegi
---------------------------------------------------------------------------------


 class CricketPlayer():
    def __init__(self,anAge,aName):
        self.name = aName
        self.age = anAge
        self.awards = list()

sachin = CricketPlayer('Sachin','46')


sachin.awards.append("Bharat ratn")
sachin.awards

Output:

['Bharat ratn']


#Nice one
----------------------------------------------------------
class CricketPlayer():
    def __init__(self,anAge,aName):
        self.name = aName
        self.age = anAge
        self.awards = list()
        self.jerseys = ('White','Blue')
        self.jerseyNums = {'White': 10,'Blue':10}
        self.records = set(['Highest Score','Num of Matches'])

sachin = CricketPlayer('Sachin','46')
sachin.records


Output:

{'Highest Score', 'Num of Matches'}
---------------------------------------------------------

class Person():
    instName = 'SaiIT' #class variable
    def __init__(self,pwd,aName):
        self.psswrd = pwd   #instance variable
        self.name = aName   #instance variable

p1 = Person('Password','Sai')
p2 = Person('P2','Shreyas')
p1.instName


Output:
'SaiIT'


#Yaha hmne class variable ko access kiya hai
-------------------------------------------------------------------------------------

class CricketPlayer():
    countryName = 'India'
    def __init__(lavanya,aName, aBat, aBall):
        lavanya.name = aName
        lavanya.bat = aBat
        lavanya.ball = aBall
jo = CricketPlayer('ram' ,'guru', 'guru')

jo.name


Output:

'ram'

# To ap dekh skte hai hm self ki jagah kuch bhi use kr skte hai , hmne yaha lavanya use kiya lekin mostly self use hota hai kyoki ye code readability ko badha deta hai.
---------------------------------------------------------

Public , Protected and Private attribute


Public attributes ko hm inside the class or outside the class kahi bhi access kr skte hai

Syntax:

name = "rishabh"

Protected attribute ko hm within a class access kr skte 
hai aur sub class mai bhi access kr skte hai

Syntax:

_name = "rishabh"


Private attribute ko hm sirf within a class access kr skte hai.

Syntax:

__name = "rishabh"


Example:

--------------------------------------------------------
class Person:
    

    def __init__(self):
        self.__passwd = 'I am Private'
        self._petName = 'I am Protected'
        self.name = 'I am Public'

ob = Person()
ob.name

Output:
'I am Public'


ob._petName

Output:
'I am Protected'



ob.__passwd

Output:

error


#Error, becoz private variable ko outside the class access nhi kr skte


--------------------------------------------------------

                Private method

Private method ko hm outside the class access nhi kr skte or na hi hm ise sub class mai access kr skte hai.

Example:

---------------------------------------------------------

class Bank:
    def __deposit(self):
        print('Deposited Money.')
    def __withdraw(self):
        print('Withdrawal Done.')

hdfc = Bank()
hdfc.__deposit()

Output:

error

#Error , becoz outside the class access nhi kr skte 

----------------------------------------------------------

                  Static method


Static method basically ek simple function hai jisme self argument use nhi hota


Example:

---------------------------------------------

class Person:
    @staticmethod
    def study(): 
        print('DS')

Person.study()

Output:

DS


#Ise hm class ke through bhi call kr skte hai is liye ise ham static method or class method bhi kahte hai.
-----------------------------------------------------


Pillar of OOPs 

1.Encapsulation


2.Inheritance




                       Encapsulation

Encapsulation ki madad se hm kisi bhi object ke component ke accessibility ko restrict kr skte hai, aisa hm getter or setter method ki help se krte hai, aur agar dusro shabdo mai kahe to the process of getting the getter and setter method is called encapsulation.

Aaiye ise example ki madad se aur clear kre 

---------------------------------------------------------- 

class Person():
    def __init__(self,pwd,aName):
        self.__psswrd = pwd

        self.name = aName
    def getPsswrd(self):
        return self.__psswrd

p1 = Person('Passbhrth','Sai')

p1.getPsswrd()


Output:

'Passbhrth'


#Ap dekh skte hai ki sbse pahle hm Password ko private kr de rahe hai , fir hm ek method ka use kr rahe hai us private variable ko access krne ke liye , so basically this process is called encapsulation.
-------------------------------------------------------



class Person():
    def __init__(self,pwd,aName):
        self.__psswrd = pwd
        self.name = aName
    def getPsswrd(self,aUsrName):
        if(aUsrName=='Sai'):
            return self.__psswrd
        else:
            return 'None'
    def setPswrd(self,newPswrd):
        self.__psswrd = newPswrd

p1 = Person('Passbhrth','Sai')



p1.__psswrd

Ouput:
error

p1.getPsswrd('Sai')

Output:
'Passbhrth'

p1.setPswrd('Rishabh')
p1.getPsswrd('Sai')

Output:

'Rishabh'


#Is process ko hm encapsulation kahte hai , the process of using getter and setter method is called encapsulation

----------------------------------------------------------

                 Inheritance

Inheritance kya hai aur iski jrurt kyo padi, aaiye example ki madad se samjhte hai ki inheritance ki jrurt kyo padi


-----------------------------------------------------------
#without inheritance


class SportsPlayer():
    def __init__(self,playerName,playerAge):
        self.name = playerName
        self.age = playerAge

class BadmintonPlayer():

    def __init__(self,playerName,playerAge,racquetName,shuttleName):
        self.name = playerName
        self.age = playerAge
        self.racquet = racquetName
        self.shuttle = shuttleName


class CricketPlayer():
    def __init__(self,playerName,playerAge,batName,ballName):
        self.name = playerName
        self.age = playerAge
        self.bat = batName
        self.ball = ballName



sai = SportsPlayer('Sai',34)
sindhu = BadmintonPlayer('Sindhu',16,'Yonex','Yonex')
sachin = CricketPlayer('Sachin',18,'MRF','MRF')


To ap yaha dekh skte hai ki sari classes mai name aur age common hai , hm baar - baar name aur age ko repeat kr rahe hai , hm inhe repeat krne ke bajaye inhe inherit kr skte hai,aur is process ko inheritance kahte hai, aur isliye hme inheritance ki jrurt padi
to SportsPlayer ko hm super class kahenge aur BadmintonPlayer or CricketPlayer ko hm derived class kahenge kyoki derived class super class ki property ko inherit krti hai.
-------------------------------------------------
# with inheritance

class SportsPlayer():
    def __init__(self,playerName,playerAge):
        self.name = playerName
        self.age = playerAge



class BadmintonPlayer(SportsPlayer):
    def __init__(self,playerName,playerAge,racquetName,shuttleName):
        SportsPlayer.__init__(self,playerName,playerAge)
        self.racquet = racquetName
        self.shuttle = shuttleName

sindhu = BadmintonPlayer('Sindhu',24,'Yonex','Yonex')


class CricketPlayer(SportsPlayer):
    def __init__(self,playerName,playerAge,batName,ballName):
        SportsPlayer.__init__(self,playerName,playerAge)
        self.bat = batName
        self.ball = ballName

------------------------------------------------------------------------------------------

Inheritance ki madad se hm code ko doobara re-use kr skte
 hai aur aur ye program ki  complexity ko kam kr deta hai.