我没有尝试弄清实现的机制，而是
memoized从PythonDecoratorLibrary获取了decorator类，并将其修改为add
reset。结果如下：我使用的技巧是
reset在装饰后的函数本身中添加一个callable属性。
class memoized2(object): """Decorator that caches a function's return value each time it is called. If called later with the same arguments, the cached value is returned, and not re-evaluated. """ def __init__(self, func): self.func = func self.cache = {} def __call__(self, *args): try: return self.cache[args] except KeyError: value = self.func(*args) self.cache[args] = value return value except TypeError: # uncachable -- for instance, passing a list as an argument. # Better to not cache than to blow up entirely. return self.func(*args) def __repr__(self): """Return the function's docstring.""" return self.func.__doc__ def __get__(self, obj, objtype): """Support instance methods.""" fn = functools.partial(self.__call__, obj) fn.reset = self._reset return fn def _reset(self): self.cache = {} class my_class: @memoized2 def my_func(self, val): print "in my_func" time.sleep(2) return val c = my_class() print "should take time" print c.my_func(55) print print "should be instant" print c.my_func(55) print c.my_func.reset() print "should take time" print c.my_func(55)
