我有一个使用asyncio
和await
模块的python程序。这是我从中获取的示例程序
here。
import asyncio
import os
import urllib.request
import await
@asyncio.coroutine
def download_coroutine(url):
"""
A coroutine to download the specified url
"""
request = urllib.request.urlopen(url)
filename = os.path.basename(url)
with open(filename, 'wb') as file_handle:
while True:
chunk = request.read(1024)
if not chunk:
break
file_handle.write(chunk)
msg = 'Finished downloading {filename}'.format(filename=filename)
return msg
@asyncio.coroutine
def main(urls):
"""
Creates a group of coroutines and waits for them to finish
"""
coroutines = [download_coroutine(url) for url in urls]
completed, pending = await asyncio.wait(coroutines)
for item in completed:
print(item.result())
if __name__ == '__main__':
urls = ["http://www.irs.gov/pub/irs-pdf/f1040.pdf",
"http://www.irs.gov/pub/irs-pdf/f1040a.pdf",
"http://www.irs.gov/pub/irs-pdf/f1040ez.pdf",
"http://www.irs.gov/pub/irs-pdf/f1040es.pdf",
"http://www.irs.gov/pub/irs-pdf/f1040sb.pdf"]
event_loop = asyncio.get_event_loop()
try:
event_loop.run_until_complete(main(urls))
finally:
event_loop.close()
我正在使用python 3.5.1
。
C:\Anaconda3\python.exe "C:\Users\XXXXXXS\AppData\Roaming\JetBrains\PyCharm Community Edition 2016.1\helpers\pydev\pydevconsole.py" 49950 49951
Python 3.5.1 |Anaconda 2.4.0 (64-bit)| (default, Jun 15 2016, 15:29:36) [MSC v.1900 64 bit (AMD64)]
Type "copyright", "credits" or "license" for more information.
当我尝试运行它时,我收到以下错误。
File "C:/Cubic/playpen/python/concepts/advanced/coroutines.py", line 29
completed, pending = await asyncio.wait(coroutines)
^
SyntaxError: invalid syntax
我同时安装了asyncio和await。
我尝试了同样的事情,但我也没有遇到任何语法错误。
C:\playpen\python>python
Python 3.5.1 |Anaconda 2.4.0 (64-bit)| (default, Jun 15 2016, 15:29:36) [MSC v.1900 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> async def foo():
... await bar
...
答案 0 :(得分:8)
await
在使用SyntaxError
关键字定义的函数内部以外的任何位置使用async
,无论是否使用{{{ 1}}装饰者。
@asyncio.coroutine
答案 1 :(得分:2)
你的文章说:
在Python 3.5中添加了async和await关键字来定义本机协同程序,并在与基于生成器的协同程序进行比较时使它们成为一种独特的类型。如果你想深入了解async和await,你会想看看PEP 492。
这意味着这些kws在Python 3.4中无效。
我现在安装了python 3.5并尝试了python
解释器
foo@foo-host:~$ python3.5
Python 3.5.0+ (default, Oct 11 2015, 09:05:38)
[GCC 5.2.1 20151010] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> async def foo():
... await bar
...
>>>
没有语法错误。
答案 2 :(得分:1)
这里有两个不同的问题。