[Python-Dev] PEP 525 (original) (raw)

Yury Selivanov yselivanov.ml at gmail.com
Wed Aug 24 11:17:53 EDT 2016

Hi Rajiv,

On 2016-08-23 10:38 PM, Rajiv Kumar wrote:

Hi Yury,

I was playing with your implementation to gain a better understanding of the operation of asend() and friends. Since I was explicitly trying to "manually" advance the generators, I wasn't using asyncio or other event loop. This meant that the first thing I ran into with my toy code was the RuntimeError ("cannot iterate async generator without finalizer set"). As you have argued elsewhere, in practice the finalizer is likely to be set by the event loop. Since the authors of event loops are likely to know that they should set the finalizer, would it perhaps be acceptable to merely issue a warning instead of an error if the finalizer is not set? That way there isn't an extra hoop to jump through for simple examples. In my case, I just called sys.setasyncgenfinalizer(lambda g: 1) to get around the error and continue playing :) (I realize that's a bad thing to do but it didn't matter for the toy cases)

Yeah, maybe warning would be sufficient. I just find it's highly unlikely that a lot of people would use async generators without a loop/coroutine runner, as it's a very tedious process.

Thank you, Yury

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