[Python-Dev] async/await in Python; v2 (original) (raw)

Wolfgang Langner tds333+pydev at gmail.com
Thu Apr 23 14:27:07 CEST 2015

On Thu, Apr 23, 2015 at 12:35 PM, Paul Sokolovsky <pmiscml at gmail.com> wrote:

Hello,

On Thu, 23 Apr 2015 12🔞51 +0300 Andrew Svetlov <andrew.svetlov at gmail.com> wrote: [] > > 3. > > async with and async for > > Bead idea, we clutter the language even more and it is one more > > thing every newbie could do wrong. > > for x in y: > > result = await f() > > is enough, every 'async' framework lived without it over years. > > async for i in iterable: > pass > > is not equal for > > for fut in iterable: > i = yield from fut But people who used Twisted all their life don't know that! They just know that "async for" is not needed and bad. I don't think it is bad nor not needed, but the syntax is not beautiful and for the 90% not doing async stuff irritating and one more thing to learn and do right/wrong.

I had also a need for async loop. But there are other solutions like channels, not needing a new syntax.

Also possible a function returning futures and yield in the loop with a sentinel.

All this goes the road down to a producer consumer pattern. Nothing more.

I know I'm a bad guy to make such comments, too bad there's a bit of truth in them, or everyone would just call me an a%$&ole right away.

Generally, I already provided feedback (on asyncio list) that asyncio is based not on native Python concepts like a coroutine, but on foreign concurrency concepts like callback or Future, and a coroutine is fitted as a second-class citizen on top of that. I understand why that was done - to not leave out all those twisteds from a shiny new world of asyncio, but sometimes one may wonder if having a clear cut would've helped (compat could then have been added as a clearly separate subpackage, implemented in terms of coroutines). Now people coming from non-coroutine frameworks who were promised compatibility see "bad" things in asyncio (and related areas), and people lured by a promise of native Python framework see bad things too. This has nothing to do with people using twisted or other async frameworks like tornado. I think a coroutine should be first class. But all this should be done in a way a beginner can handle and not design this stuff for experts only. If we do this we scare away new people.

This can be done step by step. No need to hurry.

And finally we have stackless Python but explicit. ;-)

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