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

Antoine Pitrou solipsis at pitrou.net
Thu Apr 23 10:54:43 CEST 2015

Hi,

I agree with most of Wolfgang's points below. As a data point, I haven't used asyncio for anything real (despite having approved the PEP!), but I have some extensive prior experience with Twisted and Tornado :-)

Regards

Antoine.

On Thu, 23 Apr 2015 09:30:30 +0200 Wolfgang Langner <tds333+pydev at gmail.com> wrote:

Hi,

most of the time I am a silent reader but in this discussion I must step in. I use twisted and async stuff a lot over years followed development of asyncio closely. First it is good to do differentiate async coroutines from generators. So everyone can see it and have this in mind and don't mix up booth. It is also easier to explain for new users. Sometimes generators blows their mind and it takes a while to get used to them. Async stuff is even harder. 1. I am fine with using something special instead of "yield" or "yield from" for this. C# "await" is ok. Everything else suggested complicates the language and makes it harder to read. 2. async def f(): is harder to read and something special also it breaks the symmetry in front (def indent). Also every existing tooling must be changed to support it. Same for def async, def f() async: I thing a decorator is enough here @coroutine def f(): is the best solution to mark something as a coroutine.

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. Same for with statement. The main use case suggested was for database stuff and this is also where most are best with defer something to a thread and keep it none async. All together it is very late in the development cycle for 3.5 to incorporate such a big change. Best is to give all this some more time and defer it to 3.6 and some alpha releases to experiment with. Regards, Wolfgang

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