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[Python-Dev] PEP 0492 __aenter__ & __aexit__

Brett Cannon brett at python.org
Sun Feb 7 14:07:33 EST 2016 
On Sun, 7 Feb 2016 at 08:17 Daniel Miller <dalanmiller at rethinkdb.com> wrote:

> Awesome, I missed that. Thank you Brett.
>

Welcome!


>
> Am I understanding correctly that if I'd like to avoid `async with await
> EXPR` whatever is returned from EXPR must implement `__await__` as a
> non-coroutine method? Which then I'd just be able to use `async with ...`?
>

Assuming I'm following what you're asking properly, __aenter__ needs to
return an awaitable:
https://docs.python.org/3/reference/datamodel.html?#awaitable-objects. That
is either an object that implements __await__() or a coroutine (which is
basically a generator decorated with types.coroutine).


>
>
>
> 2016-02-06 16:05 GMT-06:00 Brett Cannon <brett at python.org>:
>
>>
>>
>> On Sat, 6 Feb 2016 at 13:50 Daniel Miller <dalanmiller at rethinkdb.com>
>> wrote:
>>
>>> Hi Python-Dev Group,
>>>
>>> I am trying to implement __aenter__ and __aexit__ for the RethinkDB
>>> <https://rethinkdb.com> Python driver. Looking at the PEP I don't see
>>> any definitions as to what the expected parameters that __exit__ are
>>> supposed to take and couldn't find any other similar implementations. Is
>>> there a piece of documentation I should be looking at that I'm missing?
>>>
>>>
>>> https://www.python.org/dev/peps/pep-0492/#asynchronous-context-managers-and-async-with
>>>
>>
>> The arguments to __aexit__ are the same as __exit__ in a normal context
>> manager. See
>> https://docs.python.org/3.5/reference/datamodel.html#object.__aexit__ for
>> the official docs for __aexit__.
>>
>
>
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