13.object oriented

Object Oriented

In python, Programmers can create their own objects that have methods and attributes.

In general, Object Oriented programming allows us to create a code that is repeatable and organized.

Class is like an object constructor or a "blueprint" for creating objects.

Create a Class

class myclass:  
  x = 10 

We can use class myclass to create objects

Create a Object

Creating the object o1 and print the value of x

o1 = myclass()
print(o1.x)

Result:
10

The __init__() function

In order to understand the meaning of classes and how objects can be created using classes, we need to understand the built-in __init__() function.

__init__ is the constructor of the class. This will be called automatically, when we create object of the class.

All classes will have __init__() function, which will be executed when the class is being initiated. This __init__() function assign properties of a class to the object.

Example

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age

p1 = Person("Bhavya", 29)

print(p1.name)
print(p1.age)

Result:
Bhavya
29

The __init__() function is called automatically every time the class is being used to create a new object.

The self parameter is a reference to the current instance of the class, and is used to access variables that belong to the class.

Class Object Attribute

Generally, Attribute is the characteristic of an object. We can specify some characteristics or properties that will be same for any objects of that particular class.

Class Object Attribute

class Circle():

# Class object attribute
pi = 3.14

def __init__(self, radius=1):
    self.radius = radius
    self.area = self.pi * radius ** 2

Object Methods

Objects can also have methods. Methods in objects are functions that belong to that particular object.

Create a method in the class person

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age

  def myfunc(self):
    print("Hello my name is " + self.name)

p1 = Person("Bhavya", 29)
p1.myfunc()

Result:
Hello my name is Bhavya

Modify Object Properties

We can always modify the object properties.

Modifying the age of the person from 29 to 30

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age

p1 = Person("Bhavya", 29)
p1.age = 30

print(p1.age)

Result:
30

Delete Object properties

We can delete properties of a particular object.

Deleting the age of person p1

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age

p1 = Person("Bhavya", 29)
del p1.age

print(p1.age)

Delete an Object

To delete an object we use del keyword

Deleting the person p1

del p1