newbie developer coming from python 3.4 here.
my naive understanding is only to use the keyword async with when I see that the coroutine is a context manager?
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1hiya, sorry I made you feel this way, I did look at the PEP 492 resource and it was a little terse. I'm kinda new and stupid, just wanted to confirm it. thanks :)laycat– laycat2018-01-21 02:17:45 +00:00Commented Jan 21, 2018 at 2:17
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1Fair enough. While as a stickler for rules I think your question is off topic for this site, as a person that's been in your general situation, I'm really glad you got the explanation you were looking for. I suppose that means that this will be legitimately useful to future visitors of the site, so close vote retracted.Mad Physicist– Mad Physicist2018-01-21 04:41:12 +00:00Commented Jan 21, 2018 at 4:41
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thank you for your understanding! I did a quick search and there doesn't seem to be any comparisons between normal and asynchronous context managers, would be nice if someone could have some code examples :)laycat– laycat2018-01-22 04:28:40 +00:00Commented Jan 22, 2018 at 4:28
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@MadPhysicist hey friend how have you been? I got a notification for "nice question badge" today. thank you again for giving this question a chance (I guess our discussion aged well). hope everything is well with you and your family during this tumultuous covid period. cheers :Playcat– laycat2021-11-02 02:58:30 +00:00Commented Nov 2, 2021 at 2:58
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1I suppose it did age fairly well. Good job on getting the badge. All's well here. Hope it's the same for you.Mad Physicist– Mad Physicist2021-11-02 03:56:00 +00:00Commented Nov 2, 2021 at 3:56
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1 Answer
From PEP 492:
A new statement for asynchronous context managers is proposed:
async with EXPR as VAR: BLOCKwhich is semantically equivalent to:
mgr = (EXPR) aexit = type(mgr).__aexit__ aenter = type(mgr).__aenter__(mgr) VAR = await aenter try: BLOCK except: if not await aexit(mgr, *sys.exc_info()): raise else: await aexit(mgr, None, None, None)
So yes -- it yields into the coroutine returned from the __aenter__ method of the given context manager, runs your block once it returns, then yields into the __aexit__ coroutine.
