在 Python 中重构协程

Question

我想通过在其他功能/coroutine中移动其一些代码来重构Coroutine。但是我需要在包含的coroutine中检索其最后一个供稿，而且我不知道如何正确地做到这一点。

这是一个简单的coroutine示例。

def coroutine():
    """Yield a string containing the number sent. If 5 is sent, block for 5 turns."""
    feed = yield 0
    while True:
        if feed == 5:
            for i in range(5, 0, -1):
                feed = yield f"Blocked for {i} turns"
        feed = yield f"Received {feed}"


if __name__ == "__main__":
    my_coroutine = coroutine()
    next(my_coroutine)  # Init the coroutine

    # Print the coroutine results for inputs from 0 to 14
    for j in range(15):
        print(f"{j} -> {my_coroutine.send(j)}")

我期望（并获得）的结果是

0 -> Received 0
1 -> Received 1
2 -> Received 2
3 -> Received 3
4 -> Received 4
5 -> Blocked for 5 turns
6 -> Blocked for 4 turns
7 -> Blocked for 3 turns
8 -> Blocked for 2 turns
9 -> Blocked for 1 turns
10 -> Received 10
11 -> Received 11
12 -> Received 12
13 -> Received 13
14 -> Received 14

，我想通过将可重复使用的零件移至coroutine wait_for_five_turns来改进代码：

def wait_for_five_turns():
    """Block for 5 turns."""
    for i in range(5, 0, -1):
        feed = yield f"Blocked for {i} turns"


def coroutine():
    """Yield a string containing the number sent. If 5 is sent, block for 5 turns."""
    feed = yield 0
    while True:
        if feed == 5:
            yield from wait_for_five_turns()
        # "feed" is not up to date ! And it's logic, but bothersome.
        feed = yield f"Received {feed}"

0 -> Received 0
1 -> Received 1
2 -> Received 2
3 -> Received 3
4 -> Received 4
5 -> Blocked for 5 turns
6 -> Blocked for 4 turns
7 -> Blocked for 3 turns
8 -> Blocked for 2 turns
9 -> Blocked for 1 turns
10 -> Received 5  <----- Not what I want
11 -> Received 11
12 -> Received 12
13 -> Received 13
14 -> Received 14

有没有办法检索正确的feed值？ 还是更好的重构方法？ 祝你今天过得愉快。

Answer 1

也可以从Coroutine返回值。在当前的示例中，这将是：

def wait_for_five_turns():
    """Block for 5 turns."""
    for i in range(5, 0, -1):
        feed = yield f"Blocked for {i} turns"
    return feed


def coroutine():
    """Yield a string containing the number sent. If 5 is sent, block for 5 turns."""
    feed = yield 0
    while True:
        if feed == 5:
            feed = yield from wait_for_five_turns()
        feed = yield f"Received {feed}"

这将打印正确的预期输出：

0 -> Received 0
1 -> Received 1
2 -> Received 2
3 -> Received 3
4 -> Received 4
5 -> Blocked for 5 turns
6 -> Blocked for 4 turns
7 -> Blocked for 3 turns
8 -> Blocked for 2 turns
9 -> Blocked for 1 turns
10 -> Received 10  <-- Yeah.
11 -> Received 11
12 -> Received 12
13 -> Received 13
14 -> Received 14

我使用了错误的类型注释（发电机类型提示的第三个元素），这使我认为Coroutine只能返回。

有关信息，这是这两个功能的类型提示：

def wait_for_five_turns() -> Generator[float, str, float]: ...
def coroutine() -> Generator[float, str, float]: ...