Decorator - Python

The Decorator pattern dynamically adds responsibility to an object without modifying its structure. It provides a flexible alternative to subclassing for extending functionality. In this Python example, we define a base function say_hello and then create decorator functions add_greeting and make_it_loud that wrap the original function, adding new behavior (a greeting prefix and uppercase conversion, respectively). The @decorator_name syntax is Python’s syntactic sugar for applying a decorator, making the code concise and readable. This approach aligns with Python’s emphasis on first-class functions and dynamic programming.

def add_greeting(func):
    """Adds a greeting prefix to the function's output."""
    def wrapper(*args, **kwargs):
        return "Hello, " + func(*args, **kwargs)
    return wrapper

def make_it_loud(func):
    """Converts the function's output to uppercase."""
    def wrapper(*args, **kwargs):
        return func(*args, **kwargs).upper()
    return wrapper

@add_greeting
@make_it_loud
def say_hello(name):
    """A simple function that returns a greeting."""
    return f"hello {name}"

if __name__ == "__main__":
    print(say_hello("world"))  # Output: HELLO, WORLD