how object oriented programming works in Python.

1. WEBINAR ON PYTHON
- Jyoti Shukla (SME)

2. AGENDA
 Object-Oriented Programming in Python
 Numpy
 Pandas

3. BACKGROUND
 Procedure Oriented Programming
 OOPS concept
 Features of OOP
 Class
 Object
 Encapsulation
 Inheritance
 Polymorphism
 Abstraction

4. PROCEDURE ORIENTED PROGRAMMING
 Procedural programming uses a list of instructions
to perform computations step by step.
 It works on sequential instructions divided into small
parts called functions or procedures.
 It is not easy to maintain the codes when the project
becomes lengthy.
 Testing consumes a lot of time for enterprise
projects.
 Procedural languages do not provide a proper way
for data hiding, so it becomes less secure.

5. OBJECT-ORIENTED PROGRAMMING (OOP)
 Object-oriented programming (OOP) is a
programming paradigm based on the concept of
"objects", which can contain data member and
code.
 Data member is in the form of fields (often known as
attributes or properties), and Code, is in the form of
methods (relate it to behaviors or functions).

6. FEATURES OF OOPS
OOP
Object
Class
Encapsula
tion
Data
Abstractio
n
Inheritanc
e
Polymorp
hism

7. WHAT IS CLASS..?
 A class can be defined as a template/ blueprint that
describes the state and behavior of an object of its
type.
 A class contain fields and methods to describe the
state and behaviour of an object respectively.
Methods are the members of a class that alter the
state of an object by performing business logics.

8. REPRESENTATION OF A CLASS

9. CLASS DEFINITION

10. WHAT IS OBJECT?
 Objects are the basic run-time real entities in an object-
oriented system.
 They may represent a person, a place, a bank account,
a table of data or any item that the program must
handle.
 An object has two characteristics: Attributes & Behavior.
 Classes are just a logical representation whereas
Objects are physical representation.
 Objects upon initialization are loaded in memory.
 Syntax: reference variable=classname()
 For Example: s1 = Student()

11. VARIABLES IN CLASSES
Data/Fields/Attributes/Properties can be represented
by a variable. A variable by its definition means
something that can be changed.
Types of variable.
• instance (scope: object)
• static (scope: class)
• local(scope: method)

12. INSTANCE VARIABLES
 An instance variable of an object is a piece of
information attached to an instance (object).
 Instance variables are defined inside the instance
method and constructor by using "self" keyword.
 Example: studentId, firstname, lastname etc.
 An object can usually have many instance
variables, of many different types.
 Each object is given its own private space(Memory)
to hold its instance variable.
 Assigning a new value to an instance variable of
one object does not affect the instance variables of
any other object.

13. METHOD IN CLASSES
Types of Methods:
 instance Method
 class method
 static method

14. INSTANCE METHODS
 When we define objects, we usually have an idea of
what we want to do with them.
 I'm dealing with Person objects in an employee
database... I should be able to ask each Person
object their name, weight, and age.
 An action that involves a single object is usually
implemented as a special kind of
function/subroutine attached to that object's class,
called an instance method (or, more commonly, just
a method).

15. __INIT__() METHOD
 The __init__() method is the constructor and is
always called when an object is created.
 Constructor is a special type of method which is
used to initialize the instance variables of the class.
 Syntax of constructor declaration.
def __init__(self):
#body of constructor
 This method can take any number of
arguments. However, the first argument "self" in the
definition is special.

16. SELF
 The first argument of instance method and
constructor is a reference to the current instance of
the class.
 Similar to the keyword "this" in Java, C++ etc.
 You do not give a value for this parameter(self)
when you call the method, Python will provide it
automatically.

17. ENCAPSULATION
 Encapsulation is used to restrict access to methods
and variables. In encapsulation, code and data are
wrapped together within a single unit from being
modified by accident.
 It can be achieved by: private members of class
 __variable
 __method
 Access to this data is typically only achieved
through special methods: Getters and Setters By
using solely get() and set() methods

18. PRIVATE DATA
 Variable names starting with two underscore
characters cannot be accessed from outside of the
class. At least not directly, but they can be
accessed through public members of class.
class Encapsulation(object):
def __init__(self, a, b, c):
self.public = a
self.__private=b

19. EXAMPLE

20. INHERITANCE
 Inheritance is the capability of one class to derive or
inherit the properties from some another class.
 Benefits of inheritance are:
 It represents real-world relationships well.
 It provides reusability of a code. We don’t have to write
the same code again and again. Also, it allows us to add
more features to a class without modifying it.
 It is transitive in nature, which means that if class B
inherits from another class A, then all the subclasses of
B would automatically inherit from class A.
Syntax:
class derivedclass(base class):

21. TYPES OF INHERITANCE
1. Single inheritance
2. Multiple inheritance
3. Multilevel Inheritance
4. Hybrid Inheritance
5. Hierarchical Inheritance

22. SINGLE INHERITANCE
When a child class inherits from only one
parent class, it is called as single
inheritance.

23. MULTIPLE INHERITANCE
 When a child class inherits from multiple parent
classes.
 Python supports multiple inheritance. We specify
all parent classes as comma separated list in
bracket.

24. MULTILEVEL INHERITANCE
Multi-level inheritance is achieved when a derived
class inherits another derived class.

25. HYBRID INHERITANCE
 This form combines more than one form of
inheritance. Basically, it is a blend of more than one
type of inheritance

26. POLYMORPHISM
 Polymorphism is ability to use a common interface
for multiple forms (data types).
 It refers to the use of a single type entity (method,
operator or object) to represent different types in
different scenarios.

27. POLYMORPHISM CONTD.
We can implement polymorphism by
 Overloading
operator
method
constructor
 Overriding
method
constructor

28. POLYMORPHISM CONTD.
 Method Overloading, a way to create multiple
methods with the same name but different
arguments.
 It is achieved by passing different number
of arguments or by passing different types of
arguments.

29. POLYMORPHISM CONTD.
 Method Overriding: It allows us to change the
implementation of function in the child class which
is defined in the parent class.
 Following conditions must be met for overriding
a function:
Inheritance should be implemented. Method overriding
cannot be done within a class. We need to derive a child
class from a parent class.
The function that is redefined in the child class should
have the same definition/ signature as in the parent
class i.e. same number of parameters.

30. DATA ABSTRACTION
 It is the process of hiding the real implementation of an
application from the user and emphasizing only on
usage of it.
 E.g. when you use mobile, we need not know how
pressing a key changes the volume level. We just need
to know that pressing up button increases the volume
and the down button reduces the volume.
Why Do We Need Abstraction?
Through the process of abstraction, a programmer can
hide all the irrelevant data/process of an application in
order to reduce complexity, provide security and
increase the efficiency.

31. DATA ABSTRACTION CONTD.
Abstract class
 Abstract class are the classes which contain one or
more abstract method.
Abstract Method
 Abstract Methods are the methods which only
have declaration and no definition.

32. IMPLEMENTATION

33. Thank You