运行 python 片段涉及协程时出错

Question

python 的新手。尝试运行来自 https://docs.python.org/3/library/asyncio-task.html 的以下示例程序，但出现错误

$ python coro.py
  File "coro.py", line 3
    async def compute(x, y):
            ^
SyntaxError: invalid syntax

这是 coro.py

中的代码片段

import asyncio

async def compute(x, y):
    print("Compute %s + %s ..." % (x, y))
    await asyncio.sleep(1.0)
    return x + y

async def print_sum(x, y):
    result = await compute(x, y)
    print("%s + %s = %s" % (x, y, result))

loop = asyncio.get_event_loop()
loop.run_until_complete(print_sum(1, 2))
loop.close()

我运行宁 python 2.7.6 在 Ubuntu 14.04.

怀疑我没有asyncio，我尝试安装它（对之前的代码片段没有任何影响），得到了有趣的结果，我真的不知道它是否有效

# pip install asyncio
Downloading/unpacking asyncio
  Downloading asyncio-3.4.3.tar.gz (204kB): 204kB downloaded
  Running setup.py (path:/tmp/pip_build_root/asyncio/setup.py) egg_info for package asyncio

Installing collected packages: asyncio
  Running setup.py install for asyncio
      File "/usr/local/lib/python2.7/dist-packages/asyncio/windows_utils.py", line 83
        def pipe(*, duplex=False, overlapped=(True, True), bufsize=BUFSIZE):
                  ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/windows_events.py", line 45
        def __init__(self, ov, *, loop=None):
                                ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/futures.py", line 143
        def __init__(self, *, loop=None):
                            ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/streams.py", line 39
        def open_connection(host=None, port=None, *,
                                                   ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/base_subprocess.py", line 151
        _, pipe = yield from loop.connect_write_pipe(
                           ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/events.py", line 282
        def getaddrinfo(self, host, port, *, family=0, type=0, proto=0, flags=0):
                                           ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/coroutines.py", line 46
        yield from gen
                 ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/queues.py", line 41
        def __init__(self, maxsize=0, *, loop=None):
                                       ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/base_events.py", line 177
        yield from waiter
                 ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/subprocess.py", line 118
        return (yield from self._transport._wait())
                         ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/tasks.py", line 70
        def __init__(self, coro, *, loop=None):
                                  ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/test_utils.py", line 134
        def _run_test_server(*, address, use_ssl=False, server_cls, server_ssl_cls):
                              ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/unix_events.py", line 188
        yield from waiter
                 ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/locks.py", line 96
        def __init__(self, *, loop=None):
                            ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/selectors.py", line 39
        "{!r}".format(fileobj)) from None
                                   ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/proactor_events.py", line 386
        *, server_side=False, server_hostname=None,
         ^
    SyntaxError: invalid syntax

      File "/usr/local/lib/python2.7/dist-packages/asyncio/selector_events.py", line 57
        def _make_socket_transport(self, sock, protocol, waiter=None, *,
                                                                       ^
    SyntaxError: invalid syntax


Successfully installed asyncio
Cleaning up...

Answer 1

来自https://docs.python.org/3/library/asyncio-task.html：

The async def type of coroutine was added in Python 3.5

--> 你说你正在使用 Python 2.7，那行不通

Answer 2

似乎只在 Python 3、as per this documentation

中支持异步

运行 python 片段涉及协程时出错

Got error while running python snippet involving coroutine

python

python-asyncio