《精通Python设计模式》学习结构型之装饰器模式

这只是实现了Python的装饰器模式。

其实，python的原生的装饰器的应用比这个要强，要广的。

'''



known = {0:0, 1:1}

def fibonacci(n):
    assert(n >= 0), 'n must be >= 0'
    if n in known:
        return known[n]
    res = fibonacci(n-1) + fibonacci(n-2)
    known[n] = res
    return res

if __name__ == '__main__':
    from timeit import Timer
    t = Timer('fibonacci(100)', 'from __main__ import fibonacci')
    print(t.timeit())

'''
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 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}]
    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()))