Classes and Objects

Everything in Python is an object, which means everything we create in Python has functions/methods or attributes or both attached to an object. This is because everything in Python comes from a class.

Class is a building block (blueprint) of the object. The class is created using the keyword class. A class is a code template for creating objects.

Class Creation

For example, we want to create a blueprint for a car. A car has the following attributes (properties):

• Type of color

• Type of fuel

Cars also have some actions or functions. Those actions are called methods in a class. A method is just a function inside of a class.

• Type of car

• Capacity of car

The class is created using the keyword class as below:

class Car:
    
    # defining constructor
    def __init__(self, color, fuel):
        self.color = color
        self.fuel = fuel

A class is a blueprint for how something should be defined. It doesn’t actually contain any data. All class definitions start with the class keyword, which is followed by the name of the class and a colon. Any code that is indented below the class definition is considered part of the class’s body.

Note

Python class names are written in CapitalizedWords: MyClass or My_Class

Object/instance

Class is a blueprint, an instance is an object that is built from a class and contains data. An instance of the Car class is not a blueprint anymore as below:

# Create an object of the class
mike_car = Car("Red", "Petrol")
# Calling the objects
print(f"Color Type: {mike_car.color}")
print(f"Fule Type: {mike_car.fuel}")

Color Type: Red
Fule Type: Petrol

Instance Methods

Instance methods are functions that are defined inside a class and can only be called from an instance of that class, an instance method’s first parameter is always self.

class Car:
    
    # defining constructor
    def __init__(self, color, fuel):
        self.color = color
        self.fuel = fuel

    # defining class methods 
    def type(self):
        description = f"Car has {self.color} color and fule type is {self.fuel}."
        return description 

# Create an object of the class
mike_car = Car("Red", "Petrol")
# Call methods of the objects
print(mike_car.type())

Car has Red color and fule type is Petrol.

Add some more methods:

class Car:
    
    def __init__(self, color, fuel):
        self.color = color
        self.fuel = fuel

    def owner(self, name):
        self.name = name
        return f"Car owner name is {self.name}"
    
    def type(self):
        description = f"and has {self.color} color, fule type is {self.fuel}"
        return description

    def capacity(self, num):
        self.num = num
        return f"and capacity is: {self.num}"

mike = Car("Red", "Petrol")
car_owner = mike.owner("'Mike'")
car_type = mike.type()
car_cap = mike.capacity(3)

car_description = f"{car_owner} {car_type} {car_cap}"
print(car_description)

Car owner name is 'Mike' and has Red color, fule type is Petrol and capacity is: 3

The topic of OOP is huge, there is a lot more to Python objects and OOP and can’t cover at all.