7. Object Oriented Programing

OOP Concepts

**

Object	- Entity that contains data and procedures
Encapsulation	- Combining data and procedure into a single object
Data Hiding	- Object’s data attributes are hidden from code outside the object and access is restricted to the object’s methods - Advantages - Protects from accidental corruption - Outside code does not need to know internal structure of the object
Class	- Code that specifies the data attributes and methods of a particular type of object
Instance	- An object created from a class
Inheritance	- Creates an ‘is a’ relationship between classes - The subclass Inherits attributes and methods of the superclass

**
Class: code that specifies the data attributes and methods of a particular type of object
Object: entity that contains data and procedures
Encapsulation: combining data and procedure into a single object
Data hiding: object’s data attributes are hidden from code outside and access is restricted to the object’s methods
- protects from accidental corruption
- outside code does not need to know the internal strucutre of the object

Get - returns an attribute
set - changes an attribute

Instance: an object created from a class

Inheritance: allows a new class to acquire the attributes and methods of an existing class.

Polymorphism: an object can take different forms. It allows different classes to have methods with the same name but different implementations.

 
class 25S6D: 
 
def __init__(self, size): 
	self.size = size 
	self.names = [‘refreshed’] * size 
 
def output(self): 
	for i in range(self.size): 
		print(self.names[i])
 
# attributes: names and self

Object: entity that contains data and procedures

Advantages of OOP

• Provides a clear structure to programs
• Makes code easier to maintain, reuse, and debug
• Helps keep your code DRY (Don’t Repeat Yourself)
• Allows you to build reusable applications with less code

Class	Objects
Fruit	Apple, Banana, Mango
Car	Volvo, Audi, Toyota

import random
# The Coin class simulates a coin that can be flipped.
class Coin:
# initializes the sideup data attribute with 'Heads'.
def __init__(self):
self.sideup = 'Heads'
# The toss method generates a random number in the range of 0
# to 1. If the number is 0, then sideup is set to 'Heads'.
# Otherwise, sideup is set to 'Tails'.
def toss(self):
if random.randint(0, 1) == 0:
self.sideup = 'Heads'
else:
self.sideup = 'Tails'
# The get_sideup method returns the value referenced by sideup
def get_sideup(self):
 return self.sideup

The init() Method

All classes have a built-in method called __init__(), which is always executed when the class is being initiated.

The __init__() method is used to assign values to object properties, or to perform operations that are necessary when the object is being created.

Without the __init__() method, you would need to set properties manually for each object
Using __init__() makes it easier to create objects with initial values
__init__ runs automatically whenever you create a new object.

Self Parameter

The self parameter is a reference to the current instance of the class.
self means “this particular object”.

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
 
    def greet(self):
        print("Hello, my name is " + self.name)
 
p1 = Person("Emil", 25)
p1.greet()

can access anything using self

class Car:  
  def __init__(self, brand, model, year):  
    self.brand = brand  
    self.model = model  
    self.year = year  
  
  def display_info(self):  
    print(f"{self.year} {self.brand} {self.model}")  
  
car1 = Car("Toyota", "Corolla", 2020)  
car1.display_info()