Python
Decorators

Python Decorators

A decorator is a function that wraps another function to extend its behavior without modifying it directly.

Basic pattern

def my_decorator(func):
    def wrapper(*args, **kwargs):
        print("Before")
        result = func(*args, **kwargs)
        print("After")
        return result
    return wrapper
 
@my_decorator
def say_hello():
    print("Hello!")
 
say_hello()
# Before
# Hello!
# After

With arguments

def repeat(n):
    def decorator(func):
        def wrapper(*args, **kwargs):
            for _ in range(n):
                func(*args, **kwargs)
        return wrapper
    return decorator
 
@repeat(3)
def greet():
    print("Hi")

Key insight

@my_decorator is just syntactic sugar for say_hello = my_decorator(say_hello).

OverviewOverview