[Python]使用Decorator设计Cache

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直接上源码：

#!/usr/bin/env python# -*- coding: utf-8 -*-"""Created on 4/20/16@author: Jiezhi.G@gmail.comMy Blog: jiezhi.github.ioReference: <Expert Python Programming> Chapter 2--Decorators_Proxy Page.53"""import timeimport hashlibimport picklecache = {}def is_obsolete(entry, duration):    return time.time() - entry['time'] > durationdef compute_key(function, args, kw):    key = pickle.dumps((function.func_name, args, kw))    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 it already?            if key in cache and not is_obsolete(cache[key], duration):                print 'we got a winner'                return cache[key]['value']            # computing            result = function(*args, **kw)            # storing the result            cache[key] = {'value': result, 'time': time.time()}            return result        return __memoize    return _memoize@memoize()def very_very_very_complex_stuff(a, b):    return a + bif __name__ == '__main__':    print very_very_very_complex_stuff(2, 2)    print cache    print very_very_very_complex_stuff(2, 2)

运行后可以看到结果：

4{'dedfca39c250ca2047c5d66a13c5df2e9ac90181': {'value': 4, 'time': 1461155366.249486}}we got a winner4

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