9-_Object_Oriented_Programming_Using_Python.pdf

Object Oriented
Programming Using
Python
1

1. Introduction to Object Oriented Programming in Python
2. Difference between object and procedural oriented
programming
3. What are Classes and Objects?
4. Object-Oriented Programming methodologies:
• Inheritance
• Polymorphism
• Encapsulation
• Abstraction
2
Index

3
1. Introduction to Object Oriented
Programming in Python
Object Oriented Programming is a way of
computer programming using the idea of
“objects” to represents data and methods. It is
also, an approach used for creating neat and
reusable code instead of a redundant one.

2. Difference between Object-Oriented and
Procedural Oriented Programming
Object-Oriented Programming (OOP)
Procedural-Oriented Programming
(Pop)
It is a bottom-up approach It is a top-down approach
Program is divided into objects Program is divided into functions
Makes use of Access modifiers
‘public’, private’, protected’
Doesn’t use Access modifiers
It is more secure It is less secure
Object can move freely within member
functions
Data can move freely from function to
function within programs
It supports inheritance It does not support inheritance

5
class class1(): // class 1 is the name of the class
A class is a collection of objects or you can say it is a
blueprint of objects defining the common attributes and
behavior. Now the question arises, how do you do that?
Class is defined under a “Class” Keyword.
Example:
3. What are Classes and Objects?

6
class employee():
def __init__(self,name,age,id,salary): //creating a function
self.name = name // self is an instance of a class
self.age = age
self.salary = salary
self.id = id
emp1 = employee("harshit",22,1000,1234) //creating objects
emp2 = employee("arjun",23,2000,2234)
print(emp1.__dict__)//Prints dictionary
Creating an Object and Class in python:
Example:

7
❑ Inheritance
❑ Polymorphism
❑ Encapsulation
❑ Abstraction
4. Object-Oriented Programming
methodologies:

Inheritance:
Ever heard of this dialogue from relatives “you look exactly
like your father/mother” the reason behind this is called
‘inheritance’. From the Programming aspect, It generally
means “inheriting or transfer of characteristics from parent to
child class without any modification”. The new class is called
the derived/child class and the one from which it is derived is
called a parent/base class.

Single Inheritance:
Single level inheritance enables a derived class to inherit
characteristics from a single parent class.

class employee1()://This is a parent class
def __init__(self, name, age, salary):
self.name = name
self.age = age
class childemployee(employee1)://This is a child class
def __init__(self, name, age, salary,id):
self.name = name
self.age = age
self.id = id
emp1 = employee1('harshit',22,1000)
print(emp1.age)
Example:
Output: 22

Multilevel Inheritance:
Multi-level inheritance enables a derived class to inherit properties from an
immediate parent class which in turn inherits properties from his parent
class.
class employee()://Super class
def __init__(self,name,age,salary):
self.name = name
self.age = age
class childemployee1(employee)://First child class
self.name = name
self.age = age
Example:

class childemployee2(childemployee1)://Second child class
self.name = name
self.age = age
emp1 = employee('harshit',22,1000)
emp2 = childemployee1('arjun',23,2000)
print(emp1.age)
print(emp2.age)
Output: 22,23

Hierarchical Inheritance:
Hierarchical level inheritance enables more than one derived
class to inherit properties from a parent class.
class employee():
def __init__(self, name, age, salary): //Hierarchical Inheritance
self.name = name
self.age = age
Example:

class childemployee1(employee):
self.name = name
self.age = age
self.name = name
self.age = age
emp1 = employee('harshit',22,1000)
emp2 = employee('arjun',23,2000)

Multiple Inheritance:
Multiple level inheritance enables one derived class to inherit
properties from more than one base class.
class employee1(): //Parent class
self.name = name
self.age = age
Example:

class employee2(): //Parent class
def __init__(self,name,age,salary,id):
self.name = name
self.age = age
self.id = id
class childemployee(employee1,employee2):
def __init__(self, name, age, salary,id):
self.name = name
self.age = age
self.id = id
emp1 = employee1('harshit',22,1000)
emp2 = employee2('arjun',23,2000,1234)

Polymorphism:
You all must have used GPS for navigating the route, Isn’t it
amazing how many different routes you come across for the
same destination depending on the traffic, from a
programming point of view this is called ‘polymorphism’. It is
one such OOP methodology where one task can be performed
in several different ways. To put it in simple words, it is a
property of an object which allows it to take multiple forms.

20
Polymorphism is of two types:
❑ Compile-time Polymorphism
❑ Run-time Polymorphism

21
Compile-time Polymorphism:
A compile-time polymorphism also called as static
polymorphism which gets resolved during the compilation
time of the program. One common example is “method
overloading”

22
class employee1():
def name(self):
print("Harshit is his name")
def salary(self):
print("3000 is his salary")
def age(self):
print("22 is his age")
class employee2():
def name(self):
print("Rahul is his name")
def salary(self):
print("4000 is his salary")
def age(self):
print("23 is his age")
Example:

23
def func(obj)://Method Overloading
obj.name()
obj.salary()
obj.age()
obj_emp1 = employee1()
obj_emp2 = employee2()
func(obj_emp1)
func(obj_emp2)
Output:
Harshit is his name
3000 is his salary
22 is his age
Rahul is his name
4000 is his salary
23 is his age

24
Run-time Polymorphism:
A run-time Polymorphism is also, called as dynamic
polymorphism where it gets resolved into the run time. One
common example of Run-time polymorphism is “method
overriding”.

25
class employee():
def __init__(self,name,age,id,salary):
self.name = name
self.age = age
self.id = id
def earn(self):
pass
def earn(self): //Run-time polymorphism
print("no money")
Example:

26
def earn(self):
print("has money")
c = childemployee1
c.earn(employee)
d = childemployee2
d.earn(employee)
Output: no money, has money

27
Abstraction:
Suppose you booked a movie ticket from bookmyshow using
net banking or any other process. You don’t know the
procedure of how the pin is generated or how the verification
is done. This is called ‘abstraction’ from the programming
aspect, it basically means you only show the implementation
details of a particular process and hide the details from the
user.

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