What is Classes in Python? [A Simple Explanation and Why Use Classes?]

In simple language, classes in Python can be thought of as blueprints or templates for creating objects. Let me break it down:

1. Blueprint: Imagine you want to build a house. Before you start building, you usually have a blueprint or a plan that shows you how the house should look, with rooms, doors, and windows. In Python, a class is like that blueprint; it defines how an object should be structured and what it can do.
2. Template: Think of a class as a template for creating objects. Let’s say you have a class called Car. This class defines what a car is, its features (like wheels, engine, colour), and what actions it can perform (like start, stop, accelerate). When you create an object from this class, you create a car based on the template.
3. Objects: Objects are instances of a class. Going back to the Car example, if you create a car called “MyCar” using the Car class, “MyCar” is an object. It’s a real thing you can use, like driving your car.

Here’s a simple Python class example:

class Car:
    def __init__(self, make, model):
        self.make = make
        self.model = model
        self.speed = 0

    def start(self):
        print(f"The {self.make} {self.model} is starting.")

    def accelerate(self, mph):
        self.speed += mph
        print(f"The car is now going {self.speed} mph.")

    def stop(self):
        self.speed = 0
        print("The car has stopped.")

In this example, Car is a class. You can create multiple car objects based on this class, like this:

my_car = Car("Toyota", "Camry")
my_car.start()
my_car.accelerate(30)
my_car.stop()

So, classes in Python help you define the structure and behaviour of objects, making your code organized and reusable. It’s like creating custom data types with their characteristics and abilities.

Why use Python Classes instead of functions?

Classes and functions serve different purposes in programming, and the choice between using one or the other depends on the specific problem you are trying to solve and the design of your program. Here are some reasons why you might choose to use classes instead of functions:

1. Organizing Related Data and Functions: Classes allow you to bundle data (attributes) and the functions (methods) that operate on that data together into a single unit. This makes your code more organized, modular, and easier to understand, especially when dealing with complex systems.
2. Encapsulation: Classes can hide the internal details of how data and functions work together. This is known as encapsulation, and it helps you manage complexity. You can define an interface (public methods) that allows users of the class to interact with its data while keeping the implementation details hidden.
3. Reusability: Once you create a class, you can create multiple instances (objects) of that class. This promotes code reusability, as you can use the same class to create different objects with their unique data and behaviour.
4. Inheritance: Classes support inheritance, which means you can create new classes (subclasses) that inherit attributes and methods from existing classes (superclasses). This promotes code reuse and allows you to model real-world relationships effectively.
5. State Management: Classes can maintain state over time. For example, an object can represent a bank account with attributes like balance and account holder’s name. You can perform operations on this account; its state (balance) will change accordingly.
6. Polymorphism: Classes and inheritance enable polymorphism, which means you can write code that consistently works with objects of different classes. This is crucial for writing flexible and extensible code.
7. Object-Oriented Modeling: In some cases, using classes aligns well with the real-world problem you’re trying to model. For instance, if you’re building a zoo simulation, you might have classes for animals, enclosures, and zookeepers, each with its own data and behaviour.
8. Namespace Management: Classes help manage namespaces. Variables and functions inside a class are scoped to that class, reducing the risk of naming conflicts with other parts of your code.

While classes offer many advantages, it’s important to note that functions are more appropriate in some situations. Functions are excellent for standalone tasks, short-lived operations, and operations that don’t require maintaining state or complex relationships between data.

In practice, Python often uses a combination of classes and functions, and the choice between them depends on your program’s specific needs and design goals.