How To Use Classes In Python

In this tutorial, you will learn about classes in Python, its concepts, its creation, and how to use them effectively. The concept of classes allows programmers to use object-oriented programming, which provides a way of organizing code to make it more reusable, readable, and efficient.

Step 1: Understand Object-Oriented Programming Concepts

Before diving into classes, it’s important to understand a few concepts behind object-oriented programming:

  1. Objects: Everything in Python is an object, which is an instance of a class or a container that has attributes and behaviors (methods). For example, a list is an object that has attributes like length and behaviors like append and pop.
  2. Classes: A class is a blueprint or template for creating objects. It defines the attributes and behaviors common to all the objects of that class.
  3. Inheritance: Classes can inherit attributes and behaviors from another class, which is called the parent class. The inherited class is then called a child class.

Here’s a simple example to help visualize this concept. If we have a class called “Car,” it may have attributes like “color” and “speed,” and behaviors like “accelerate” and “brake.” We can then create objects of that class, like “BMW,” “Mercedes,” and “Toyota,” which inherit those attributes and behaviors from the “Car” class.

Step 2: Create a Class in Python

To create a class, use the keyword class followed by the class name and a colon. Then, define the attributes and methods within the class body. For example:

1
2
3
4
5
class MyClass:
    x = 5
 
    def print_hello(self):
        print("Hello!")

In this example, we created a class called MyClass with an attribute x and a method called print_hello. The self parameter in the method definition refers to the instance of the class on which the method is called. It is important to include it as the first parameter for every method in a class.

Step 3: Create Objects of the Class

To create objects of the class, call the class as if it were a function. Here’s how to create an object of the MyClass class:

1
2
3
obj1 = MyClass()
print(obj1.x)
obj1.print_hello()
 
5
Hello!

In this example, we created an object obj1 of the MyClass class. We can then access its attributes and methods using the dot notation (obj1.x and obj1.print_hello()).

Step 4: Understand the __init__ Method

The __init__ method is a special method in classes that are automatically called when an object is created. It is used to initialize the object’s attributes. Here’s an example of how to use the __init__ method:

1
2
3
4
5
6
7
8
class Car:
    def __init__(self, brand, model, year):
        self.brand = brand
        self.model = model
        self.year = year
 
    def age(self):
        return 2021 - self.year

In this example, we have a Car class with an __init__ method. When we create a new object of the Car class, we pass the brand, model, and year as arguments to the __init__ method.

1
2
my_car = Car("Toyota", "Corolla", 2015)
print(my_car.age())
 
6

Here, we created a my_car object of the Car class and passed the required arguments to the __init__ method. Then, we called the age method to calculate the age of the car.

Full Code:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
class MyClass:
    x = 5
 
    def print_hello(self):
        print("Hello!")
 
obj1 = MyClass()
print(obj1.x)
obj1.print_hello()
 
class Car:
    def __init__(self, brand, model, year):
        self.brand = brand
        self.model = model
        self.year = year
 
    def age(self):
        return 2021 - self.year
 
my_car = Car("Toyota", "Corolla", 2015)
print(my_car.age())

Output:

5
Hello!
6

Conclusion:

In this tutorial, you learned about classes in Python, their creation, and usage, along with concepts like __init__ method and object-oriented programming.

Understanding and using classes effectively will help you create more organized, reusable, and efficient code.

As you advance in your programming journey, you can further explore concepts like inheritance, polymorphism, and encapsulation, which are key aspects of object-oriented programming.