[Python-ideas] PEP 525: Asynchronous Generators

[Stefan Behnel]

Yury Selivanov schrieb am 06.08.2016 um 18:39:
> You can implement async generators using async iteration protocol as
> it was defined in PEP 492.
> [...]
> Essentially, because pure Python async generators work fine
> with 'async for' and will continue to do so in 3.6, I think
> there shouldn't be technical problems to add asynchronous
> generators in Cython.

Hmm, I thought that at least interoperability might get in the way. I guess
I'll just have to give it a try...


> 2. It's extremely unlikely that somebody will design a system that
> switches coroutine runners *while async/awaiting a coroutine*.

Yes, I guess so.


> But even in this unlikely use case, you can
> easily stack finalizers following this pattern:
> 
>   old_finalizer = sys.get_asyncgen_finalizer()
>   sys.set_asyncgen_finalizer(my_finalizer)
>   try:
>     # do my thing
>   finally:
>     sys.set_asyncgen_finalizer(old_finalizer)

That only works for synchronous code, though, because if this is done in a
coroutine, it might get suspended within the try block and would leak its
own finalizer into the outer world.

Stefan