Objects

Objects:

Object is an instance of class
Each Object has an unique ID.
We have to store ID into Object Reference.
It is a variable in which we can store ID of an
It will create a new object of specified class and will return ID of object which we can assign into reference variable.

Syntax:

Object-Reference = ClassName()

Member Access Operator

Members of an object can be access by using member access operator.

Syntax:

ObjectName.memberName

Access Modifiers

Classical object-oriented languages, such as C++ and Java, control the access to class resources by public, private and protected keywords
Python doesn't have any mechanism that effectively restricts access to any instance variable or method.
Python prescribes a convention of prefixing the name of the variable/method with single or double underscore to emulate the behavior of protected and private access specifiers.
Python provide 3 access modifiers
- Public
- Protected
- Private

Public Access Modifiers

All members in a Python class are public by default. Any member can be accessed from outside the class environment

#Example

class employee:
  def __init__(self,name,sal):
    self.name=name
    self.salary=sal

emp=employee("Amit Jain",2000)
print(emp.salary)
emp.salary=3000
print(emp.salary)

2000
3000

Protected Access Modifiers

Python's convention to make an instance variable protected is to add a prefix _ (single underscore) to it. This effectively prevents it to be accessed, unless it is from within a sub-class.
In fact, this doesn't prevent instance variables from accessing or modifying the instance.

#Example

class employee:
  def __init__(self,name,sal):
    self._name=name
    self._salary=sal

emp=employee("Amit Jain",2000)
print(emp._salary)
emp._salary=3000
print(emp._salary)

2000
3000

Private Access Modifiers

Similarly, a double underscore __ prefixed to a variable makes it private. It gives a strong suggestion not to touch it from outside the class. Any attempt to do so will result in an AttributeError
In fact, this doesn't prevent instance variables from accessing or modifying the instance.

#Example

class employee:
  def __init__(self,name,sal):
    self.__name=name
    self.__salary=sal

emp=employee("Amit Jain",2000)
print(emp.__salary)
emp.__salary=3000
print(emp.__salary)

AttributeError: 
'employee' object 
has no attribute 
'__salary'

#Program to create 2 box type of objects a and b of size 2 x 3 x 4 and 4 x 5 x 3. display volume of both boxes.

Data members

Length
Breadth
Height

Member Functions

setdimension(x,y,z)
volume()

class Box :
  def setDimension(self,x,y,z):
    self.L = x
    self.B = y
    self.H = z 
  def volume(self):
    v = self.L*self.B*self.H
    print("Volume is",v) 

a = Box()
b = Box()
a.setDimension(2,3,4)
b.setDimension(4,5,3)
a.volume()
b.volume()

Volume is 24
Volume is 60

#Program to create 2 rectangles a and b of size 5 x 7 and 10 x 20 . Display area, perimeter of a and area of b.

Data members

Length
Breadth

Member Functions

setDimension(x,y)
Area()
Perimeter()

class Rectangle :
  def setDimension(self,x,y):
    self.length = x
    self.breadth = y
  def area(self):
    a=self.length*self.breadth
    print("Area is ",a)
  def perimeter(self):
    p=2*(self.length+self.breadth )
    print("Perimeter is ",p)
  
a = Rectangle()
b = Rectangle()
a.setDimension(5,7)
b.setDimension(10,20)
a.area()
a.perimeter()

Area is 35
Perimeter is 24
Area is 200

#WAP to create 2 circle type of objects a, b of radius 5 and 2. Display area of a. Display area and circumference of b.

Data members

radius

Member Functions

setRadius(n)
Area()
circumference()

class circle :
  def setradius(this,n):
    this.R = n
  def area(this):
    a =3.14*this.R**2
    print("Area is ",a)
  def circumference(this):
    c =2*3.14*this.R
    print("Circumference is ",c)

a = circle()
b = circle()
a.setradius(5)
b.setradius(2)
a.area()
b.area()
b.circumference()

Area is 78.5
Area is 12.56
Circumference is 12.5

#WAP to create 2 Worker type of objects : a ( name=Raja , wages=500 , wdays=5 ) b ( name=Gaja , wages=400, wdays=8 ) Showdata and payment of both workers as well as total payment. .

Data members

name
wages
wdays

Member Functions

setData(n,w,d)
showdata()
payment()

class worker:
  def setData(self,n,w,d):
    self.name=n
    self.wages=w
    self.wdays=d
  def showData(self):
    print("Name is ",self.name)
    print("Wages is ",self.wages)
    print("Wdays is ",self.wdays)
  def payment(self):
    p=self.wages*self.wdays
    print("Payment is ",p)

a=worker()
b=worker()
a.setData("Raja",500,5)
b.setData("Gaja",400,8)
a.showData()
a.payment()
b.showData()
b.payment()

Name is Raja 
Wages is 500
Wdays are 5
Payment is 2500
Name is Gaja
Wages is 400
Wdays are 8
Payment is 3200

#WAP to create 2 set type of objects : a = { 2 , 5 , 3 } b = { 6 , 10 , 4 } Display sum both sets as well as mean of b.

Data members

Member Functions

setData(x,y,z)
sum()
mean()

class Set:
  def setData(self,x,y,z):
    self.n1=x
    self.n2=y
    self.n3=z 
  def sum(self):
    s=self.n1+self.n2+self.n3
    print("sum is ",s) 
  def mean(self):
    s=self.n1+self.n2+self.n3
    m=s/3
    print("Mean is ",m) 

a=Set()
b=Set()
a.setData(2,5,3)
b.setData(6,10,4)
a.sum() 
b.sum()
b.mean()

Sum is 10
Sum is 20
Mean is 6.6666667

CCITcoder

Introduction to Python

Conditional statements

Iterative statements

Functions

OOPs

Collection

Module and Exception

DateBase

Inherintance

GUI

Introduction to Python

Conditional statements

Iterative statements

Functions

OOPs

Collection

Module and Exception

DateBase

Inherintance

GUI

Objects

Objects:

Member Access Operator

Access Modifiers

Public Access Modifiers

Protected Access Modifiers

Private Access Modifiers