OOPs Reading Material

 

1. What is OOPs?

Object-Oriented Programming is a way of approaching, designing and developing software, so that the components of the software and the interactions between them resemble real-life objects and their interactions.

Proper usage of OOPs concepts helps us build well-organized systems that are easy to use and extend.

2. What are the advantages of OOPs?

The advantages of OOPs:

• Easier way to analyse and solve bugs
• Reusability of code through inheritance
• Effective problem solving
• Elimination of code redundancy

3. What are the principles of OOPs?

The principles of OOPs involve,

• Abstraction
• Encapsulation
• Inheritance
• Polymorphism

Abstraction in python is defined as a process of handling complexity by hiding unnecessary information from the user. This is one of the core concepts of object-oriented programming (OOP) languages.

Polymorphism is an OOPs concept. The word polymorphism means having many forms. It refers to the use of a single type entity (method, operator, or object) to represent different types in different scenarios

4. What are Classes?

A

class

is a prototype from which objects are created. Classes can be used to bundle related attributes and methods. An instance of a

class

is an Object.

Code

1

2

3

4

5

6

7

8

class Mobile:

def __init__(self, model, storage):

self.model = model

self.storage = storage

obj = Mobile("iPhone 12 Pro", "128GB")

print(obj.model)

PYTHON

Output

iPhone 12 Pro

5. What is 

__init__

 / 

constructor

 in Python?

The

__init__

is a special method used to initialize values to attributes.

Code

1

2

3

4

5

6

7

8

9

class Mobile:

def __init__(self, model, camera):

self.model = model

self.camera = camera

def make_call(self, number):

print("calling..{}".format(number))

mobile = Mobile("Nikon", "D850")

mobile.make_call("12345")

PYTHON

In the above example, the

model

and

camera

attributes are initialized with the values that are passed to the

__init__

method.

6. What is 

self

 in OOPs?

In Python, the

self

is the first parameter of methods that represents the instance of the class. Therefore, to call attributes and methods of a class, the programmer need to use

self

within the class.

self

is not a keyword and has no special meaning in Python. Writing this parameter as self is a convention. We can use other names but it is highly discouraged.

Code

1

2

3

4

5

6

7

8

9

10

11

12

13

14

class Dog:

def __init__(self, name, age):

self.name = name

self.age = age

def info(self):

print("My name is {}".format(self.name))

def make_sound(self):

print("Bow Wow")

dog1 = Dog('Rex', 2)

dog1.info()

PYTHON

Collapse

Output

My name is Rex

7. What are class methods?

Methods which need access to class attributes but not instance attributes are marked as class methods. For class methods, we send

cls

as a parameter indicating we are passing the class.

Code

1

2

3

4

5

6

7

8

9

class Cart:

flat_discount = 0

min_bill = 100

@classmethod

def update_flat_discount(cls, new_flat_discount):

cls.flat_discount = new_flat_discount

Cart.update_flat_discount(25)

print(Cart.flat_discount)

PYTHON

Output

25

@classmethod

decorator marks the method below it as a class method.

8. What is Inheritance?

Inheritance is a mechanism by which a class inherits attributes and methods from another class.

The class whose attributes and methods are inherited is known as the Super/Base/Parent Class. And the class that inherits the attributes and methods from the parent class is the Sub/Derived/Child Class.

9. Write an example program to show Inheritance?

Code

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

class Product:

def __init__(self, name, price, deal_price, ratings):

self.name = name

self.price = price

self.deal_price = deal_price

self.ratings = ratings

self.you_save = price - deal_price

def display_product_details(self):

print("Product: {}".format(self.name))

print("Price: {}".format(self.price))

print("Deal Price: {}".format(self.deal_price))

print("You Saved: {}".format(self.you_save))

print("Ratings: {}".format(self.ratings))

class ElectronicItem(Product):

def set_warranty(self, warranty_in_months):

self.warranty_in_months = warranty_in_months

def get_warranty(self):

return self.warranty_in_months

e = ElectronicItem("TV", 45000, 40000, 3.5)

e.display_product_details()

PYTHON

Collapse

Output

Product: TV

Price: 45000

Deal Price: 40000

You Saved: 5000

Ratings: 3.5

In the above example, the child class ElectronicItem inherits all the attributes and methods from the parent class Product.

10. What are the types of Inheritance?

There are 5 types of Inheritance in Python:

1. Single Inheritance
2. Multiple Inheritance
3. Multilevel Inheritance
4. Hierarchical Inheritance
5. Hybrid Inheritance

Single Inheritance:

When a Child class inherits attributes and methods from a single Parent class, it is called Single Inheritance.

Multiple Inheritance:

When a Child class inherits attributes and methods from more than one Parent class, it is called Multiple Inheritance.

Multilevel Inheritance:

When a Child class inherits attributes and methods from another Child class, it is called Multilevel Inheritance.

Hierarchical Inheritance:

When more than one Child class inherits attributes and methods from a single Parent class, it is called Hierarchical Inheritance.

Hybrid Inheritance:

Any combination of more than one type of inheritance is called Hybrid Inheritance.

11. What is Encapsulation?

While modelling objects with object-oriented programming, we bundle related information together to clearly separate information of different objects.

The bundling of related attributes and methods together is called Encapsulation.

Classes can be used to bundle related attributes and methods.

12. What is Method Overriding?

Method Overriding is an OOPs concept related to Inheritance. When a child class method overrides the parent class method of the same name, parameters and return type, it is known as Method Overriding.

Method Overriding allows us to change the implementation of a function in the child class that is defined in the parent class.

Code

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

class Product:

def __init__(self, name, price, deal_price, rating):

self.name = name

self.price = price

self.deal_price = deal_price

self.rating = rating

self.you_save = price - deal_price

def display_product_details(self):

print("Product: {}".format(self.name))

print("Price: {}".format(self.price))

print("Deal Price: {}".format(self.deal_price))

print("You Saved: {}".format(self.you_save))

print("Rating: {}".format(self.rating))

def get_deal_price(self):

return self.deal_price

class ElectronicItem(Product):

def display_product_details(self):

super().display_product_details()

print("Warranty {} months".format(self.warranty_in_months))

def set_warranty(self, warranty_in_months):

self.warranty_in_months = warranty_in_months

def get_warranty(self):

return self.warranty_in_months

e = ElectronicItem("Laptop",45000, 40000,3.5)

e.set_warranty(10)

e.display_product_details()

PYTHON

Collapse

Output

Product: Laptop

Price: 45000

Deal Price: 40000

You Saved: 5000

Rating: 3.5

Warranty 10 months

In the above example, the

display_product_details()

method in the ElectronicItem class overrides the

display_product_details()

method of the Product class.