23.11.2016, 01:34, Nathaniel Smith kirjoitti:
On Tue, Nov 22, 2016 at 2:22 PM, Alex Grönholm
<alex.gronh...@nextday.fi <mailto:alex.gronh...@nextday.fi>> wrote:
> I'm not sure where asyncio_extras's async generator implementation
assumes
> you're using asyncio. Could you elaborate on that?
If I'm reading it right, it assumes that the only two things that
might be yielded to the coroutine runner are either (a) the special
yield wrapper, or (b) an awaitable object like an asyncio.Future. This
works on asyncio, because that's all the asyncio runner supports, but
it doesn't work with (for example) curio. async_generator (like native
async generators) allows arbitrary objects to be yielded to the
coroutine runner.
You are misreading the code. It is in no way limited to what asyncio
accepts. It doesn't even import asyncio in the asyncyield or generator
modules. The only parts of the library that depend on PEP 3156 event
loops are the ones that involve executors and threads.
> Native async generators don't support "yield from" either, so I
didn't try
> to add that until there's a new PEP that defines its exact semantics.
Yeah, one of the motivations for async_generator has been to figure
out what the semantics for native generators should be :-). The native
async generators in 3.6 use the same implementation trick as
async_generator (not entirely sure if Yury got it from me, or if it's
an independent invention), and the yield from implementation is partly
motivated as a proof of concept / testing ground for hopefully getting
it into 3.7. The yield from semantics are pretty straightforward
though, I think.
> As for
> aclose/asend/athrow support, I will have to look into that.
>
> Could we synchronize the implementations so that they're compatible with
> each other? I would've preferred there to be only a single
implementation
> (asyncio_extras was published first, but admittedly I didn't
advertise it
> that well) but now it'd be best if we work together, wouldn't you agree?
Makes sense to me :-). I think the obvious approach would be for
async_extras to just depend on async_generator, since AFAICT
async_generator is pretty much complete, and like you say, there's not
much point in carrying around two copies of the same thing. But if you
have another suggestion I'd be interested to hear it...
I may consider that at some point, but I'm not yet comfortable with
those extended capabilities. Meanwhile I will add any missing
functionality (asend, athrow etc.) to mine.
One thing I noticed is that there seems to be no way to detect async
generator functions in your implementation. That is something I would
want to have before switching.
-n
>
> 22.11.2016, 22:32, Nathaniel Smith kirjoitti:
>
> On Nov 22, 2016 6:22 AM, "Alex Grönholm" <alex.gronh...@nextday.fi
<mailto:alex.gronh...@nextday.fi>> wrote:
>>
>> Does this library offer any advantages over the same functionality in
>> asyncio_extras?
>
> You would probably know better than me, but last time I looked, the
> generator code in asyncio_extras didn't support asend/athrow/aclose,
didn't
> support yield from, and took shortcuts that assume that you're using
asyncio
> as your coroutine runner. So I believe async_generator is more
complete and
> more correct (in the sense that it sticks strictly to implementing the
> language level semantics for async generators without assuming any
> particular runner).
>
> Of course asyncio_extras has lots of other handy things in it too, while
> async_generator is very strictly focused on just this one thing.
(Well, I
> threw in an implementation of aclosing too, since you can't really
use async
> generators without it, but that's pretty trivial.) It might make
sense for
> asyncio_extras to out-source generator handling to async_generator?
Or not.
>
> -n
>
>
--
Nathaniel J. Smith -- https://vorpus.org
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