TIL: Undecorating a functools.wraps decorated function

In the Python standard library there is a function in the functools library that allows decorated functions to carry forward their original docstring. Executing it is rather easy:

from functools import wraps
def kerpow(f):
    """Prints the string KERPOW!"""
    @wraps(f)
    def wrapper(*args, **kwds):
        print(f'KERPOW {f.__name__}!')
        return f(*args, **kwds)
    return wrapper

Let's try it out.

@kerpow
def adder(a,b):
    """Adds the arguments together"""
    return a+b

Let's call the function. What we should get in addition to the sum of the values passed is the printed value of "KERPOW" plus the name of the function.

adder(1,2)

As mentioned, the functools.wraps decorator preserves the docstring:

adder.__doc__

As you can see, functools.wraps is an easy addition to any decorator that makes keeping documentation valid trivial to do.

However, what if we want to use the adder function without printing "KERPOW adder!" to the terminal? In other words, can we remove the decorator?

Fortunately, because we used functools.wraps we can do just that. You see, what functools.wraps does is add a __wrapped__ attribute to the wrapped function. If we want to restore the function to the original we do this:

adder_1 = adder.__wrapped__

Now if we call adder, we won't see "KERPOW adder!" any longer going to the terminal.

adder_1(2, 3)

Postscript

In a follow-up discussion about this TIL I learned that functools.wraps is syntactical sugar for the functools.update_wrapper() function.

mo.md(
    r"""

    """
)

import marimo as mo