Python: Coroutines StopIteration异常

Question

我正试着用.send()来输入字典。下面是我的代码片段

def coroutine(func):
    def start(*args, **kwargs):
        cr = func(*args, **kwargs)
        next(cr)
        return cr
    return start

@coroutine
def putd(di):

    print("via coroutines adding a key : value to dictionary")

    try:
        item = yield
        for key, value in item.items():
            if key in di:
                print("Key : {0} already exists".format(key))
            else:
                di[key] = value
        print(di)
    except StopIteration :
        print("yield frame got closed")


di = {}
gobj = putd(di)
gobj.send({"plan" : "shuttle"})
gobj.close()

我相信我正在正确地处理exception，但是我还是得到了StopIteration的异常。

scratch.py
Traceback (most recent call last):
via coroutines adding a key : value to dictionary
{'plan': 'shuttle'}
File "scratch.py", line 39, in <module>
    gobj.send({"plan" : "shuttle"})
StopIteration

Process finished with exit code 1

我是没有正确处理这个例外，还是遗漏了什么？ANy非常感谢您的帮助。

Answer 1

你的协同线在第一次发送/屈服后就退出了。这将生成一个StopIteration，并且您不能在协同线本身中处理它，但只能在调用send时处理。从医生那里：

send()方法返回生成器产生的下一个值，如果生成器退出而不产生另一个值，则引发StopIteration。

@coroutine
def putd(di):

    print("via coroutines adding a key : value to dictionary")

    try:
        item = yield
        for key, value in item.items():
            if key in di:
                print("Key : {0} already exists".format(key))
            else:
                di[key] = value
        print(di)
    except StopIteration :
        print("yield frame got closed")
    # here is an implicit  return None  which terminates the coroutine

我想你想要保持协同线存活，接受任意数量的发送，直到一个显式的关

@coroutine
def putd(di):

    print("via coroutines adding a key : value to dictionary")

    try:
        while True:
            item = yield
            for key, value in item.items():
                if key in di: 
                    print("Key : {0} already exists".format(key))
                else:
                    di[key] = value
            print(di)
    except GeneratorExit:
        print("yield frame got closed")

请注意，现在捕获了GeneratorExit异常。