问题
I am using Python 3.5, which, according to PEP 492 should have access to the async with syntax, yet I get a SyntaxError when I try to use it. What am I doing wrong?
In [14]: sys.version
Out[14]: '3.5.2 (default, Oct 11 2016, 04:59:56) \n[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.38)]'
In [15]: async with aiohttp.ClientSession() as session:
File "<ipython-input-15-9799c5ce74cf>", line 1
async with aiohttp.ClientSession() as session:
^
SyntaxError: invalid syntax
回答1:
You can not use async with without async function. As the docs say:
It is a SyntaxError to use async with outside of an async def function.
But this code will work:
async def some_function():
async with aiohttp.ClientSession() as session:
pass
Or have a look at the example from the docs.
来源：https://stackoverflow.com/questions/42285685/python-3-5-async-with-results-in-syntaxerror-why