使用装饰器为Python函数做缓存

写了个函数作为装饰器为Fibonacci数列做缓存，做了一下性能比较。

#!/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)

输出结果：

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

Fib with cache costs: datetime.timedelta(0, 0, 672000)