python实现装饰器模式

"""
修饰器模式
"""
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):
    assert n >= 0, 'n must be >= 0'
    return n if n in (0, 1) else fibonacci(n - 1) + fibonacci(n - 2)


@memoize
def nsum(n):
    assert n >= 0, 'n must be >= 0'
    return 0 if n == 0 else n + nsum(n - 1)


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()))