使用裝飾器爲Python函數做緩存

寫了個函數作爲裝飾器爲Fibonacci數列做緩存，做了一下性能比較。

#!/usr/bin/python
# coding: UTF-8

import datetime
now = datetime.datetime.now
from functools import wraps

def cache(func):
    caches = {}
    @wraps(func)
    def wrap(*args):
        if args not in caches:
            caches[args] = func(*args)
        return caches[args]
    return wrap

def fib(num):
    if num < 2:
        return 1
    return fib(num-1) + fib(num-2)

fib_with_cache = cache(fib)

start = now()
for i in range(10):
    fib(30)
end = now()
print "Fib without cache costs: %r" % (end - start)

start = now()
for i in range(10):
    fib_with_cache(30)
end = now()
print "Fib with cache costs: %r" % (end - start)

輸出結果：

Fib without cache costs: datetime.timedelta(0, 6, 219000)
Fib with cache costs: datetime.timedelta(0, 0, 672000)