# python设计模式–装饰器模式

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def fibonacci(n):
assert(n >= 0), 'n must be >= 0'
return n if n in (0, 1) else fibonacci(n-1) + fibonacci(n-2)
if __name__ == '__main__':
from timeit import Timer
t = Timer('fibonacci(8)', 'from __main__ import fibonacci')
print(t.timeit())

# coding: utf-8

import functools

def memoize(fn):
known = dict()

@functools.wraps(fn)
def memoizer(*args):
if args not in known:
known[args] = fn(*args)
return known[args]

return memoizer

@memoize
def nsum(n):
'''返回前n个数字的和'''
assert(n >= 0), 'n must be >= 0'
return 0 if n == 0 else n + nsum(n-1)

@memoize
def fibonacci(n):
'''返回斐波那契数列的第n个数'''
assert(n >= 0), 'n must be >= 0'
return n if n in (0, 1) else fibonacci(n-1) + fibonacci(n-2)

if __name__ == '__main__':
from timeit import Timer
measure = [{'exec': 'fibonacci(100)', 'import': 'fibonacci',
'func': fibonacci}, {'exec': 'nsum(200)', 'import': 'nsum',
'func': nsum}]
for m in measure:
t = Timer('{}'.format(m['exec']), 'from __main__ import \
{}'.format(m['import']))
print('name: {}, doc: {}, executing: {}, time: \
{}'.format(m['func'].__name__, m['func'].__doc__,
m['exec'], t.timeit()))