Python Classes and Objects

Logically group data (attributes) and functions(methods)
Class is like a design template
Easy to reuse
Easy to build upon (Upgrade or add more details i.e. attributes or methods)

Example: Employees would have specific attributes and methods. In an employee class, individual employee objects are called an instance of a class.

Class Creation

class employee:
Pass

Object Creation

employee1 = employee()
employee2 = employee()

Both employees are the object of the class and have a separate memory
2 employee instance created for employee class.
Note: Employee class doesn’t have any attribute or methods at this stage

For the above employee class let us create attributes and methods

Incorrect Method:

employee1.name = ‘Raj’
employee1.age = 28

employee1.name = ‘Alex’
employee1.age = 26

Define the attributes when defining the class and not when creating instances.
or
Inherit the parent class and add new attributes in the child class.

Correct Method:

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

employee1= employee(‘Raj’, 28)
employee2 = employee(‘Alex’, 26)

Add methods to Class

Note: self automatically takes the object name.

def return_employee(self):
return ‘{}{}’.format(self.name, self.age)

print(employee1.return_employee())
print(employee2.return_employee())

call the class method using class name

print(employee.return_employee(employee1)
print(employee.return_employee(employee2)

Note – Each method inside the class can automatically take instance as 1st argument