如何使用异步在Python 3.5 /等待？ [英] How to use async/await in Python 3.5?

问题描述

 ＃！的/ usr / bin中/ env的python3
＃ -  *  - 编码：UTF-8  -  *  - 
进口时间异步高清富（）：
  等待time.sleep（1）富（）
 

我不能让这个死简单的例子来运行：

  RuntimeWarning：协程'富'是从来没有期待已久的富（）
 

解决方案

运行协同程序需要的事件循环的。使用 ASYNCIO（）库来创建一个

 进口ASYNCIO循环= asyncio.get_event_loop（）
loop.run_until_complete（富（））
loop.close（）
 

另请参阅的任务和协同程序的的 ASYNCIO 文档。

然而要注意 time.sleep（）是的不的一个awaitable对象。它返回无，所以你以后得到一个例外情况1秒：

 ＆GT;＆GT;＆GT; loop.run_until_complete（富（））
回溯（最近通话最后一个）：
  文件＆LT;＆标准输入GT;，1号线，上述＆lt;＆模块GT;
  文件/Users/mj/Development/Library/buildout.python/parts/opt/lib/python3.5/asyncio/base_events.py，线路342，在run_until_complete
    返回future.result（）
  文件/Users/mj/Development/Library/buildout.python/parts/opt/lib/python3.5/asyncio/futures.py，线路274，在结果
    提高self._exception
  文件/Users/mj/Development/Library/buildout.python/parts/opt/lib/python3.5/asyncio/tasks.py，239线，在_step
    结果= coro.send（值）
  文件＆LT;＆标准输入GT;，2号线，在富
类型错误：对象NoneType不能使用'等待'前pression
 

您应该使用<$c$c>asyncio.sleep()协程来代替：

 异步高清富（）：
    等待asyncio.sleep（1）
 

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import time

async def foo():
  await time.sleep(1)

foo()

I couldn't make this dead simple example to run:

RuntimeWarning: coroutine 'foo' was never awaited foo()

解决方案

Running coroutines requires an event loop. Use the asyncio() library to create one:

import asyncio

loop = asyncio.get_event_loop()
loop.run_until_complete(foo())
loop.close()

Also see the Tasks and Coroutines chapter of the asyncio documentation.

Note however that time.sleep() is not an awaitable object. It returns None so you get an exception after 1 second:

>>> loop.run_until_complete(foo())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/mj/Development/Library/buildout.python/parts/opt/lib/python3.5/asyncio/base_events.py", line 342, in run_until_complete
    return future.result()
  File "/Users/mj/Development/Library/buildout.python/parts/opt/lib/python3.5/asyncio/futures.py", line 274, in result
    raise self._exception
  File "/Users/mj/Development/Library/buildout.python/parts/opt/lib/python3.5/asyncio/tasks.py", line 239, in _step
    result = coro.send(value)
  File "<stdin>", line 2, in foo
TypeError: object NoneType can't be used in 'await' expression

You should use the asyncio.sleep() coroutine instead:

async def foo():
    await asyncio.sleep(1)

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