当我们相对一个对象添加新功能的时候,无非就是下面这三种方法:
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
:param n:
:return:
'''
assert (n >= 0), 'n must be >=0'
return 0 if n == 0 else n + nsum(n - 1)
@memoize
def fibonacci(n):
'''
返回斐波那契额数列的第N个数
:param n:
:return:
'''
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(100)', '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()))