请求示例代码以了解 return 值的协程中 throw() 的 return 值

Question

"Python Essential Reference (Fourth Edition)" 一书在第 106 页谈到 return 协程的 throw() 值，returns 值，即在 yield 语句中同时接收和发射:

我正在尝试编写一个示例代码来查看 throw() 函数在所描述情况下的 return 值是否为 "the value passed to the next yield"。以下是我到目前为止编写的示例代码：

def line_splitter(delimiter=None):
    print("Ready to split")
    result = None
    try:
        while True:
            line = (yield result)
            result = line.split(delimiter)
    except GeneratorExit:
        print("Receiver done")
    except RuntimeError:
        print "RuntimeError captured"

s = line_splitter(",")
s.next()
s.send("A,B,C")
r=s.throw(RuntimeError,"You're hosed!")

问题是，当我运行最后一行在协程中使用 throw() 引发异常时，RuntimeError 被按预期捕获，但也生成了 StopIteration 异常并传播了此异常向外所以我无法得到结果 throw() returns。那么，如何修改我现有的示例代码来验证文中的语句："If you raise an exception in a coroutine using throw(), the value passed to the next yield in the coroutine will be returned as the result of throw()"？非常感谢。

PS: 我正在使用 python 2.7.12

Answer 1

如果你 'run out of yields' 提出 StopIteration。一个简单的（但荒谬的？）解决方法是 yield 异常（或其他任何东西）返回：

def line_splitter(delimiter=None):
    print("Ready to split")
    result = None
    try:
        while True:
            line = yield result
            result = line.split(delimiter)
    except GeneratorExit as exc:
        print("Receiver done")
        yield exc
    except RuntimeError as exc:
        print("RuntimeError captured")
        yield exc

s = line_splitter(",")
next(s)
s.send("A,B,C")
r=s.throw(RuntimeError,"You're hosed!")
print(r)

请求示例代码以了解 return 值的协程中 throw() 的 return 值

Ask for a sample code to understand the return value of throw() in a coroutine which returns values

python

exception-handling

exception

coroutine

python-2.7