Python decorators

cache.py

def cache(f):
    '''Memorizes the return value for a function regardless arguments beyond the first one.'''
    class cache:
        UNSET = 'unset'
        def __init__(self, f):
            self.f = f
            self.ret = cache.UNSET
        def __call__(self, *args, **kwargs):
            if self.ret == cache.UNSET:
                self.ret = self.f(*args, **kwargs)
            return self.ret
    return cache(f)

count.py

def count(f):
    '''Count and pass as argument the number of times the function was called.'''
    class counter:
        def __init__(self, f):
            self.f = f
            self.c = 0
        def __call__(self, *args, **kwargs):
            ret = self.f(*args, **dict(kwargs, count=self.c))
            self.c = self.c + 1
            return ret
    return counter(f)

memoize.py

def memoize(f):
    '''Memorizes the return value for a function for given arguments.'''
    class memodict(dict):
        def __init__(self, f):
            self.f = f
        def __call__(self, *args):
            return self[args]
        def __missing__(self, key):
            ret = self[key] = self.f(*key)
            return ret
    return memodict(f)