Python decorator? - can someone please explain this?

Question

Apologies this is a very broad question.

The code below is a fragment of something found on the web. The key thing I am interested in is the line beginning @protect

Answer 1

A decorator is a function that takes a function as its only parameter and returns a function. This is helpful to “wrap” functionality with the same code over and over again.

We use @func_name to specify a decorator to be applied on another function.

Following example adds a welcome message to the string returned by fun(). Takes fun() as parameter and returns welcome().

def decorate_message(fun):

    # Nested function
    def addWelcome(site_name):
        return "Welcome to " + fun(site_name)

    # Decorator returns a function
    return addWelcome

@decorate_message
def site(site_name):
    return site_name;

print site("StackOverflow")

Out[0]: "Welcome to StackOverflow"

Decorators can also be useful to attach data (or add attribute) to functions.

A decorator function to attach data to func

def attach_data(func):
       func.data = 3
       return func

@attach_data
def add (x, y):
       return x + y

print(add(2, 3))
# 5    
print(add.data)
# 3