How do I create a "signature-changing" decorator with decorator.py? about decorator HOT 4 CLOSED

from inspect import signature, Parameter
from makefun import wraps, add_signature_parameters

def mydec(func):
    """
    A decorator to add 2 keyword arguments to the decorated function.

    :param func:
    :return:
    """
    # add parameters to the wrapped function signature
    func_sig = signature(func)
    new_kw_param = Parameter('new_kw', kind=Parameter.POSITIONAL_OR_KEYWORD, default=None)
    another_new_kw_param = Parameter('another_new_kw', kind=Parameter.POSITIONAL_OR_KEYWORD, default=None)
    new_sig = add_signature_parameters(func_sig, last=(new_kw_param, another_new_kw_param))

    # create the new function with modified signature
    @wraps(func, new_sig=new_sig)
    def new_func(*args, **kwargs):
        new_kw = kwargs.pop('new_kw')
        another_new_kw = kwargs.pop('another_new_kw')
        if new_kw:
            print(new_kw)

        return func(*args, **kwargs)

    # return the new function
    return new_func


# ------ Test
@mydec
def foo(a):
    return a + 1

assert foo(1) == 2
assert foo(1, new_kw='bar') == 2  # prints 'bar'
print(help(foo))                  # new signature

from inspect import signature, Parameter
from decopatch import function_decorator, DECORATED
from makefun import wraps, add_signature_parameters

@function_decorator
def mydec(func=DECORATED, msg_to_print="hello"):
    """
    A decorator to add 2 keyword arguments to the decorated function.

    :param msg_to_print: the message to print
    :return:
    """
    # add parameters to the wrapped function signature
    func_sig = signature(func)
    new_kw_param = Parameter('new_kw', kind=Parameter.POSITIONAL_OR_KEYWORD, default=None)
    another_new_kw_param = Parameter('another_new_kw', kind=Parameter.POSITIONAL_OR_KEYWORD, default=None)
    new_sig = add_signature_parameters(func_sig, last=(new_kw_param, another_new_kw_param))

    # create the new function with modified signature
    @wraps(func, new_sig=new_sig)
    def new_func(*args, **kwargs):
        new_kw = kwargs.pop('new_kw')
        another_new_kw = kwargs.pop('another_new_kw')
        if new_kw:
            print("%s %s" % (msg_to_print, new_kw))

        return func(*args, **kwargs)

    # return the new function
    return new_func

# ------ Test
@mydec          # no parenthesis ! default behaviour
def foo(a):
    return a + 1

assert foo(1) == 2
assert foo(1, new_kw='bar') == 2  # prints 'hello bar'

@mydec(msg_to_print="oops")
def foo2(a):
    return a + 2

assert foo2(1) == 3
assert foo2(1, new_kw='bar') == 3  # prints 'oops bar'