How to strip decorators from a function in Python

Question

Let's say I have the following:

def with_connection(f):
    def decorated(*args, **kwargs):
        f(get_connection(...), *args, **kwargs)
    return decorated

@with_connection
def spam(connection):
    # Do something

I want to test the spam function without going through the hassle of setting up a connection (or whatever the decorator is doing).

Given spam, how do I strip the decorator from it and get the underlying "undecorated" function?

Answer 1

In the general case, you can't, because

@with_connection
def spam(connection):
    # Do something

is equivalent to

def spam(connection):
    # Do something

spam = with_connection(spam)

which means that the "original" spam might not even exist anymore. A (not too pretty) hack would be this:

def with_connection(f):
    def decorated(*args, **kwargs):
        f(get_connection(...), *args, **kwargs)
    decorated._original = f
    return decorated

@with_connection
def spam(connection):
    # Do something

spam._original(testcon) # calls the undecorated function