import functools

d = dict()
s = set()


def register(function):
    global d

    d[function.__name__] = function

    return function


def depends_on(lst, function=None):
    global d

    if not function:
        return functools.partial(depends_on, lst)

    @functools.wraps(function)
    def inner(*args, **kwargs):
        global s
        if inner in s:
            raise Exception("Detected cycle dependencies")
        s.add(inner)

        for function_name in lst:
            # globals()[function_name]()
            d[function_name]()

        s.remove(inner)

        return function(*args, **kwargs)

    d[function.__name__] = inner
    return inner