Python OOPS

Object Oriented Programming Style

Agenda

  • What is OOPS ?

  • Classes

  • Objects

  • Real life example

What is OOPS?

Object Oriented Programming Style (OOPS) is a programming style that deals with classes & objects.

The main aim of object-oriented programming is to implement real-world entities, for example, object, classes, abstraction, inheritance, polymorphism, etc.

A class is a blueprint for the object.

What is a class ?

What is an object ?

What is a class ?

An object is an entity that has a state and some behaviour.

Car

Car

Blueprint

Blueprint

Blueprint

Factory

Blueprint

Factory

Blueprint

Blueprint

Blueprint

Properties:

Blueprint

Properties:

- Model name

Blueprint

Properties:

- Model name

- Color

Blueprint

Properties:

- Model name

- Color

- Price

Blueprint

Properties:

- Model name

- Color

- Price

 

Functionalities:

 

Blueprint

Properties:

- Model name

- Color

- Price

 

Functionalities:

- Drive

Blueprint

Properties:

- Model name

- Color

- Price

 

Functionalities:

- Drive

- Lock/Unlock

Properties:

- Model name

- Color

- Price

 

Functionalities:

- Drive

- Lock/Unlock

Properties:

- Model name

- Color

- Price

 

Functionalities:

- Drive

- Lock/Unlock

class Car:
    # body

Properties:

- Model name

- Color

- Price

 

Functionalities:

- Drive

- Lock/Unlock

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

Properties:

- Model name

- Color

- Price

 

Functionalities:

- Drive

- Lock/Unlock

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

Properties:

- Model name

- Color

- Price

 

Functionalities:

- Drive

- Lock/Unlock

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

Ignore the 'self' keyword for now. We'll cover it later.

Properties:

- Model name

- Color

- Price

 

Functionalities:

- Drive

- Lock/Unlock

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")

Ignore the 'self' keyword for now. We'll cover it later.

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")

Blueprint

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")

Blueprint

# Main part of the program

Blueprint

# Main part of the program
c1 = Car()
class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")

Blueprint

c1

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")

# Main part of the program
c1 = Car()

Blueprint

c1

c2

# Main part of the program
c1 = Car()
c2 = Car()
class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")

Blueprint

# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black

c1

c2

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")

Blueprint

# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

c1

c2

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

Properties

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

Data members

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

drive()

lock()

unlock()

Data members

Functions

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

model:

color:

price:

Hatchback

Black

100000

c1

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

model:

color:

price:

Hatchback

Black

100000

c1

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

model:

color:

price:

Hatchback

Black

100000

c1

c2

model:

color:

price:

Hatchback

Black

100000

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

model:

color:

price:

Hatchback

Black

100000

c1

c2

model:

color:

price:

Hatchback

Black

100000

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

model:

color:

price:

Hatchback

Black

100000

c1

c2

model:

color:

price:

Hatchback

Black

100000

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

model:

color:

price:

Hatchback

Black

100000

c1

c2

model:

color:

price:

Hatchback

Black

100000

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

c2.color = "Red"
print(c2.color)    # Red

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

model:

color:

price:

Hatchback

Black

100000

c1

c2

model:

color:

price:

Hatchback

Red

100000

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

c2.color = "Red"
print(c2.color)    # Red

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

model:

color:

price:

Hatchback

Black

100000

c1

c2

model:

color:

price:

Hatchback

Red

100000

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

c2.color = "Red"
print(c2.color)    # Red

c2.fuel = "CNG"

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

model:

color:

price:

Hatchback

Black

100000

c1

c2

model:

color:

price:

fuel:

Hatchback

Red

100000

CNG

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

c2.color = "Red"
print(c2.color)    # Red

c2.fuel = "CNG"

class Car

model

color

price

drive()

lock()

unlock()

Data members

Class methods

model:

color:

price:

Hatchback

Black

100000

c1

c2

model:

color:

price:

fuel:

Hatchback

Red

100000

CNG

class Car:
    model = "Hatchback"
    color = "Black"
    price = 100000

    def drive(self):
        print("Zoom zoom zoom")

    def lock(self):
        print("Car is now locked")

    def unlock(self):
        print("Car is now unlocked")


# Main part of the program
c1 = Car()
c2 = Car()

print(c1.color)     # Black
print(c1.model)     # Hatchback
print(c1.price)     # 100000

c2.color = "Red"
print(c2.color)    # Red

c2.fuel = "CNG"
print(c2.fuel)      # CNG
  • The first argument of a method of a class is generally referred as 'self'.
  • self refers to the calling object.
  • This argument is passed implicitly by the Python interpreter and need not be mentioned while calling.

self keyword

class ComplexNumber:
    real = 0
    imaginary = 0

    def print(self):
        print("{} + {}i".format(self.real, self.imaginary))


# 5 + 3i
x = ComplexNumber()
x.real = 5
x.imaginary = 3
x.print()

Example: Complex Numbers

Write a class to store and perform operations on complex numbers.

  • __init__() is a special method inside a class that allows us to define the properties/attributes while creating it.
  • It is a special method that is called/invoked automatically when the object is created. The user need not call it.
  • It is similar to "Constructors" in C++ and Java.

__init__() method

Everything is an Object

In Python, pretty much everything is an object, whether it is a number, a function or even modules.

a = 5

print(type(a))   # <class 'int'>

b = "May the Force be with you"
c = 63.29

def hello():
    print("Hello world")
    
    
print(type(b))	     # <class 'str'>
print(type(c))	     # <class 'float'>	
print(type(hello))   # <class 'function'>

Extra Reading Material

https://www.scaler.com/topics/oops-concepts-in-python/

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