yield_from

python3.3 新加的yield from 语句

1.yield from

def my_chain(*args, **kwargs):
    for my_iterable in args:
        yield from my_iterable
        # yield from  相当于下面的:
        # for value in my_iterable:
        #     yield value

2.yield from 会把值循环遍历　

def g1(iterable):
    yield iterable


def g2(iterable):
    yield from iterable


for value in g1(range(5)):
    print(value)
for value in g2(range(5)):
    print(value)

# 结果
range(0, 5)
0
1
2
3
4

2.yield from 主动处理StopIteration异常

final_result = {}

def sales_sum(pro_name):
    total = 0
    nums = []
    while True:
        x = yield
        print(pro_name + "销量: ", x)
        if not x:
            break
        total += x
        nums.append(x)
    return total, nums


def middle(key):
    while True:
        final_result[key] = yield from sales_sum(key)
        print(key + "销量统计完成！！.")


def main():
    data_sets = {
        "bobby牌面膜": [1200, 1500, 3000],
        "bobby牌手机": [28, 55, 98, 108],
        "bobby牌大衣": [280, 560, 778, 70],
    }
    for key, data_set in data_sets.items():
        print("start key:", key)
        m = middle(key)
        m.send(None)  # 预激middle协程
        for value in data_set:
            m.send(value)  # 给协程传递每一组的值
        m.send(None)
    print("final_result:", final_result)


if __name__ == '__main__':
    main()


def sales_sum(pro_name):
    total = 0
    nums = []
    while True:
        x = yield
        print(pro_name + "销量: ", x)
        if not x:
            break
        total += x
        nums.append(x)
    return total, nums


if __name__ == "__main__":
    my_gen = sales_sum("bobby牌手机")
    my_gen.send(None)
    my_gen.send(1200)
    my_gen.send(1500)
    my_gen.send(3000)
    try:
        my_gen.send(None)
    except StopIteration as e:
        result = e.value
        print(result)