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addreset。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)
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