import time

import hashlib

import pickle

cache = {}

def is_obsolete(entry, duration):

return time.time() - entry['time'] > duration

def compute_key(function, args, kw):

key = pickle.dumps((function.__name__, args, kw))

# returns the pickle representation of an object as a byte object

# instead of writing it on a file

# creates a key from the "frozen" key generated in the last step

return hashlib.sha1(key).hexdigest()

def memoize(duration=10):

def _memoize(function):

def __memoize(*args, **kw):

key = compute_key(function, args, kw)

# do we have the value on cache?

if key in cache and not is_obsolete(cache[key], duration):

print('we already have the value')

return cache[key]['value']

# if we didn't

print('calculating...')

result = function(*args, **kw)

# storing the result

cache[key] = {'value': result, 'time': time.time()}

return result

return __memoize

return _memoize