【11.6】生成器进阶--yield from

#!/usr/bin/env python
# -*- coding:utf-8 -*-

final_result = {}


# 子生成器
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


# 委托生成器
def middle(key):
    while True:
        final_result[key] = yield from sales_sum(key)
        print(key+'销量统计完成！！.')


# 调用方
def main():
    data_sets = {
        '小米9': [1200, 1500, 3000],
        '小米8': [28, 55, 98, 108],
        '小米5': [200, 560, 778, 70],
    }
    for key, data_set in data_sets.items():
        print('start key:', key)
        m = middle(key)
        # 预激middle协程
        m.send(None)
        for value in data_set:
            # 给协程传递每一组的值
            m.send(value)
        # 结束
        m.send(None)
    print('final_result:', final_result)


if __name__ == '__main__':
    main()

start key: 小米9
小米9销量:  1200
小米9销量:  1500
小米9销量:  3000
小米9销量:  None
小米9销量统计完成！！.
start key: 小米8
小米8销量:  28
小米8销量:  55
小米8销量:  98
小米8销量:  108
小米8销量:  None
小米8销量统计完成！！.
start key: 小米5
小米5销量:  200
小米5销量:  560
小米5销量:  778
小米5销量:  70
小米5销量:  None
小米5销量统计完成！！.
final_result: {'小米9': (5700, [1200, 1500, 3000]), '小米8': (289, [28, 55, 98, 108]), '小米5': (1608, [200, 560, 778, 70])}

yield from最主要的用法

# main调用方、g1（委托生成器）、gen 子生成器
# yield from会在调用方与子生成器之间建立一个双向通道
def g1(gen):
    yield from gen


def main():
    g = g1()
    g.send(None)

yield from 处理了StopIteration的异常

yield from 其他用法

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# python3.3新加了yield from语法


from itertools import chain


my_list = [1, 2, 3]
my_dict = {
    'zy1': 'http://projectsedu.com',
    'zy2': 'http://www.imooc.com'
}


# yield from iterable（可迭代对象）
def my_chain(*args, **kwargs):
    for my_iterable in args:
        yield from my_iterable
        # for value in my_iterable:
        #     yield value


for value in my_chain(my_list, my_dict, range(5, 10)):
    print(value)

1
2
3
zy1
zy2
5
6
7
8
9