Is there anything python function decorators can do that I can't do with first class functions?

Question

I'm trying to understand Python function decorators, but so far I don't see any case where a function decorator can do something I couldn't do using first class functions.

As an example, the logger decorator is often given as a simple example of a useful function decorator:

def logger(f):
    def new_f():
        print("Calling %s" % f.__name__)
        return f()
return new_f

This decorator is then classically used together with a function we want to log, as so:

@logger
def fun1():
    [do something]

However, for the same result we could just define func1 and wrap it with logger:

def fun2():
    [do something]
def logged_fun2():
    return logger(fun2)()

Calling logged_fun2 is analogue to calling fun1. In addition, when we wrap fun2 with logger we can still call the original fun2 without logging if we wish to.

Are there things I can do with decorators that I can't do using first class functions? Or is it better to look at decorators as a form of syntactic sugar for wrapping functions?

Answer 1

Decorator syntax:

@deco
def f(...):
    ...

is defined as exactly equivalent to the following syntax:

def f(...):
    ...
f = deco(f)

So no, there's nothing decorators can do that first-class functions can't. Decorators are first-class functions.