Class Methods and Static Methods

As we continue to grow and improve the Chirpy project, we’ve encountered a new challenge. While we’ve made great progress with instance methods and class attributes, we need to handle tasks that apply to the entire class rather than individual instances.

• How can we create a guest user with a random username each time without manually supplying one every time?

• Or, how do we check if a chirp meets the character limit in a reusable and efficient manner?

Simply relying on instance methods and class attributes isn’t enough in these cases. We can’t manually handle tasks like generating guest users or validating content length whenever we need them. We need methods that act on the class, not just individual objects. This is where class methods and static methods come into play!

These methods help us manage and interact with data that applies to the class, not just individual instances. They make our code more efficient and reusable, enabling us to centralize and automate certain tasks.

In object-oriented programming (OOP), both class and static methods allow us to organize code within a class more powerfully. But they are used for different purposes. Let’s break them down, especially in the context of Chirpy.

Class methods (@classmethod)

Class methods are used when you need to operate on the class itself rather than individual class instances. They allow us to modify the state of the class, and this change will apply to all instances of the class.

• They’re bound to the class (not the instance).

• They can modify the class state (which affects all instances).

• They have access to the class via the cls argument, similar to how instance methods use self to refer to the instance.

Syntax

To declare a method as a class method, use the @classmethod decorator. This method will automatically receive the class as the first argument (cls), which is conventionally used to refer to the class (you can use other names, but cls is the convention).

Here’s the syntax: