Python class decorator arguments

@Cache(max_hits=100, timeout=50) calls __init__(max_hits=100, timeout=50), so you aren’t satisfying the function argument.

You could implement your decorator via a wrapper method that detected whether a function was present. If it finds a function, it can return the Cache object. Otherwise, it can return a wrapper function that will be used as the decorator.

class _Cache(object):
    def __init__(self, function, max_hits=10, timeout=5):
        self.function = function
        self.max_hits = max_hits
        self.timeout = timeout
        self.cache = {}

    def __call__(self, *args):
        # Here the code returning the correct thing.

# wrap _Cache to allow for deferred calling
def Cache(function=None, max_hits=10, timeout=5):
    if function:
        return _Cache(function)
    else:
        def wrapper(function):
            return _Cache(function, max_hits, timeout)

        return wrapper

@Cache
def double(x):
    return x * 2

@Cache(max_hits=100, timeout=50)
def double(x):
    return x * 2