Understanding @staticmethod, @classmethod, and Instance Methods in Python

Hi Pythonistas!

When working with classes in Python, you might have come across instance methods, class methods, and static methods. These three types of methods have different behaviors and use cases. Let’s break them down in the simplest way possible!

1. Instance Methods (Normal Methods)
These are the most common methods in Python classes. They:
✅ Operate on an instance of the class
✅ Can access and modify instance attributes
✅ Receive self as the first argument

code

class Car:
    def __init__(self, brand):
        self.brand = brand  # Instance attribute

    def show_brand(self):  # Instance method
        return f"This car is a {self.brand}"

my_car = Car("Tesla")
print(my_car.show_brand()) 

Output

This car is a Tesla

Here, show_brand() is an instance method because it uses self to access the instance attribute brand.

2. Class Methods (@classmethod)
✅ Work on the class itself, not on an instance
✅ Can modify class-level attributes
✅ Receive cls (class) as the first argument instead of self

class Car:
    manufacturer = "Unknown"  # Class attribute

    @classmethod
    def set_manufacturer(cls, name):
        cls.manufacturer = name  # Modifies class-level attribute

Car.set_manufacturer("Toyota")
print(Car.manufacturer)  # Output: Toyota

Output

Toyota

Here, set_manufacturer() is a class method that changes the manufacturer for all instances of Car.

✅ Best Use Case: When you need to modify or access class-level attributes instead of instance attributes.

3. Static Methods (@staticmethod)
✅ Behave like regular functions, but live inside a class
✅ Don’t need access to self (instance) or cls (class)
✅ Can be used when the method does not modify instance or class data

code

class Car:
    @staticmethod
    def general_info():
        return "Cars have wheels and an engine."

print(Car.general_info())  # Output: Cars have wheels and an engine.

Output

Cars have wheels and an engine.

Here, general_info() doesn’t need access to instance or class attributes, making it a static method.

✅ Best Use Case: When a function logically belongs to a class but doesn’t depend on instance or class attributes.

Comparison Table

Feature	Instance Method	Class Method	Static Method
Access self?	✅ Yes (Instance attributes)	❌ No	❌ No
Access cls?	❌ No	✅ Yes (Class attributes)	❌ No
Modifies instance attributes?	✅ Yes	❌ No	❌ No
Modifies class attributes?	❌ No	✅ Yes	❌ No
Works without instance?	❌ No	✅ Yes	✅ Yes

When to Use What?
Use an instance method when you need to work with an object’s attributes.
Use a class method when you need to modify class attributes.
Use a static method when you need a helper function inside a class, but it doesn’t depend on any class or instance attributes.

Hope this makes it easy to understand!, Please share your suggestions at afsal@parseltongue.co.in