Object Oriented Programming in Python

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OBJECT ORIENTED PROGRAMMING
WITH PYTHON

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LET’S DISCUSS
 Why OOPs
 Classes & Objects
 Inheritance
 Revisiting Types & Exceptions
 Polymorphism
 Operator Overloading
 Method Overriding
 Quick Quiz

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THE CURRENT SCENARIO
Let’s store employee data
Why OOPs
# Ask for the name of the employee
name = input("Enter the name of the employee: ")
# Ask for the age of the employee
age = input("Enter the age of the employee: ")
# Print the collected information
print(f"Employee Name: {name}")
print(f"Employee Age: {age}")

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LET’S IMPROVE IT
# Function to input employee data (name and age)
def input_employee_data():
name = input("Enter the name of the employee: ")
age = input("Enter the age of the employee: ")
return name, age
# Function to print employee information
def print_employee_info(name, age):
print(f"Employee Name: {name}")
print(f"Employee Age: {age}")
name, age = input_employee_data()
print_employee_info(name, age)
# Ask for the name of the employee
name = input("Enter the name of the employee: ")
# Ask for the age of the employee
age = input("Enter the age of the employee: ")
# Print the collected information
print(f"Employee Name: {name}")
print(f"Employee Age: {age}")
Why OOPs

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IS THAT GOOD ENOUGH?
# Function to input employee data (name and age)
def input_employee_data():
name = input("Enter the name of the employee: ")
age = input("Enter the age of the employee: ")
return name, age
# Function to print employee information
def print_employee_info(name, age):
print(f"Employee Name: {name}")
print(f"Employee Age: {age}")
name, age = input_employee_data()
print_employee_info(name, age)
Why OOPs
class Employee:
def input_employee_data(self):
self.name = input("Enter the name of the employee: ")
self.age = input("Enter the age of the employee: ")
def print_employee_info(self):
print(f"Employee Name: {self.name}")
print(f"Employee Age: {self.age}")
# Create an instance of the Employee class
employee = Employee()
# Input employee data using the class method
employee.input_employee_data()
# Print employee information using the class method
employee.print_employee_info()

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PARADIGMS OF PROGRAMMING
# Ask for the name of the employee
name = input("Enter the name : ")
# Ask for the age of the employee
age = input("Enter the age of the employee: ")
# Print the collected information
print(f"Employee Name: {name}")
print(f"Employee Age: {age}")
# Function to input employee data (name and age)
def input_employee_data():
name = input("Enter the name of the employee: ")
age = input("Enter the age of the employee: ")
return name, age
# Function to print employee information
def print_employee_info(name, age):
print(f"Employee Name: {name}")
print(f"Employee Age: {age}")
name, age = input_employee_data()
print_employee_info(name, age)
class Employee:
def input_employee_data(self):
self.name = input("Enter the name of the employee: ")
self.age = input("Enter the age of the employee: ")
def print_employee_info(self):
print(f"Employee Name: {self.name}")
print(f"Employee Age: {self.age}")
# Create an instance of the Employee class
employee = Employee()
# Input employee data using the class method
employee.input_employee_data()
# Print employee information using the class method
employee.print_employee_info()
Procedural Functional Object Oriented

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CLASSES
Classes are used to create our
own type of data and give them
names.
Classes are “Blueprints”

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OBJECTS
Any time you
create a class and
you utilize that
“blueprint” to
create “object”.

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CLASSES AND OBJECTS IN ACTION

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CLASSES AND OBJECTS IN ACTION
class Employee:
def input_employee_data(self):
self.name = input("Enter the name of the employee: ")
self.age = input("Enter the age of the employee: ")
def print_employee_info(self):
print(f"Employee Name: {self.name}")
print(f"Employee Age: {self.age}")
# Create an instance of the Employee class
employee1 = Employee()
# Create another instance of the Employee
class
employee2 = Employee()
# Yet another instance of the Employee class
employee3 = Employee()

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ANATOMY OF A CLASS
class Employee:
...
Class is a
Blueprint

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METHODS IN CLASS
# Create an instance of the Employee class
employee = Employee()
# Input employee data using the class method
employee.input_employee_data()
class Employee:
def input_employee_data(self):
self.name = input("Enter the name of the employee: ")
self.age = input("Enter the age of the employee: ")

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WHAT IS “self”
class Employee:
def input_employee_data(self):
self.name = input("Enter the name of the employee: ")
self.age = input("Enter the age of the employee: ")
self refers to the current object that was just created.

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ATTRIBUTES
class Employee:
def input_employee_data(self):
self.name = input("Enter the name of the employee: ")
self.age = input("Enter the age of the employee: ")

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SET ATTRIBUTES WHILE CREATING THE OBJECT
class Employee:
def input_employee_data(self):
self.name = input("Enter the name of the employee: ")
self.age = input("Enter the age of the employee: ")
# Driver Code
# Create an instance of the Employee class
employee = Employee()
# Input employee data using the class method
employee.input_employee_data()
class Employee:
def __init__(self, name, age):
self.name = name
self.age = age
# Driver Code
name = input("Enter the name of the employee: ")
age = input("Enter the age of the employee: ")
# Create an instance of the Employee class
employee = Employee(name, age)
# Print the employee data
print("Employee Name:", employee.name)
print("Employee Age:", employee.age)

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LET’S VISUALISE __init__()
class Employee:
def __init__(self, name, age):
self.name = name
self.age = age
self.name
self.age
name
age
# Create an instance
employee = Employee(name, age)

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WHERE ARE THESE EMPLOYEE WORKING?
class Employee:
org = 'CompanyName'
def input_employee_data(self):
self.name = input("Enter the name of the employee: ")
self.age = input("Enter the age of the employee: ")
def print_employee_info(self):
print(f"Employee Name: {self.name}")
print(f"Employee Age: {self.age}")
emp = Employee()
print(emp.org)
Class Variables

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WHAT ABOUT CODE REUSABILITY?

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INHERITENCE
class Human:
...
class Employee:
...
class Human:
...
class Employee(Human):
...
Inheritance enables us
to create a class that
“inherits” methods,
variables, and attributes
from another class.

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INHERITENCE IN ACTION
class Human:
def __init__(self, height):
self.height = height
class Employee(Human):
def __init__(self, height, name, age):
super().__init__(height)
self.name = name
self.age = age

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YOU ARE ALREADY USING CLASSES
https://docs.python.org/3/library/stdtypes.html#str
surprise

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EXCEPTIONS
BaseException
+-- KeyboardInterrupt
+-- Exception
+-- ArithmeticError
| +-- ZeroDivisionError
+-- AssertionError
+-- AttributeError
+-- EOFError
+-- ImportError
| +-- ModuleNotFoundError
+-- LookupError
| +-- KeyError
+-- NameError
+-- SyntaxError
| +-- IndentationError
+-- ValueError
...

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POLYMORPHISM
 Poly – many
 Morph - shapes

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OPERATOR OVERLOADING
 Some operators such as
+ and - can be
“overloaded” such that
they can have more
abilities beyond simple
arithmetic.
class MyNumber:
def __init__(self, num=0):
self.num = num
def __add__(self, other):
return self.num * other.num

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HOW IT WORKED?
 We override the __add__ method
 https://docs.python.org/3/reference/datamod
el.html?highlight=__add__#object.__add__

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METHOD OVERRIDING
class Human:
def __init__(self, name, age):
self.name = name
self.age = age
def introduce(self):
print(f"Hello, I am {self.name} and I am {self.age} years old.")
class Employee(Human):
def __init__(self, name, age, employee_id):
super().__init__(name, age)
self.employee_id = employee_id
# Method overriding
def introduce(self):
print(f"Hello, I am {self.name}, an employee with ID {self.employee_id}.")

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QUIZ TIME

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THANKS