[Python-Dev] PEP 550 v4: coroutine policy (original) (raw)

Antoine Pitrou antoine at python.org
Tue Aug 29 16:10:01 EDT 2017

Le 29/08/2017 à 21:59, Yury Selivanov a écrit :

This absolutely needs to be fixed, and the only way (that I know) it can be fixed is to revert the "every coroutine has its own LC" statement (going back to the semantics coroutines had in PEP 550 v2 and v3).

I completely agree with this. What I don't understand is why example #2 can't work the same.

"await bar()" and "await waitfor(bar())" are actually quite different. Let me illustrate with an example:

b1 = bar() # bar() is not running yet await b1 b2 = waitfor(bar()) # bar() was wrapped into a Task and is being running right now await b2 Usually this difference is subtle, but in asyncio it's perfectly fine to never await on b2, just let it run until it completes. If you don't "await b1" -- b1 simply will never run.

Perhaps... But still, why doesn't bar() inherit the LC at the point where it was instantiated (i.e. foo()'s LC in the examples)? The fact that it's later passed to wait_for() shouldn't matter, right? Or should it?

Regards

Antoine.

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