Methods in Python Instance, Class, and Static

In Python, methods are functions included within the definition of a class.

There are three types of methods, which differ in how they are defined and what they have access to:

Instance Methods

Instance methods are methods that act on the instances of a class. They have access to the attributes of those instances through the self parameter.

They are the most common methods in Python and are defined within a class using def.

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def greet(self):
        return f"Hello, I'm {self.name} and I'm {self.age} years old."

# Creating an instance of Person
person1 = Person("Luis", 30)

# Calling the instance method
print(person1.greet())  # Output: Hello, I'm Luis and I'm 30 years old.

Class Methods

Class methods are methods that act on the class itself (instead of individual instances of the class).

They are defined using the @classmethod decorator and have access to the class through the cls parameter.

class Car:
    discount = 0.1  # 10% discount for all cars

    def __init__(self, brand, model, price):
        self.brand = brand
        self.model = model
        self.price = price

    @classmethod
    def apply_discount(cls, price):
        return price * (1 - cls.discount)

# Using the class method
final_price = Car.apply_discount(30000)
print(f"Final price with discount: ${final_price}")  # Output: Final price with discount: $27000.0

Static Methods

Static methods are methods that relate to the class but do not require access to its attributes.

They are defined using the @staticmethod decorator, and do not depend on the instance (self) or the class (cls).

class Utilities:
    @staticmethod
    def add(a, b):
        return a + b

# Using the static method
result = Utilities.add(3, 5)
print(f"Result of the addition: {result}")  # Output: Result of the addition: 8