[Python-ideas] Async API

Yury Selivanov yselivanov.ml at gmail.com
Thu Oct 25 21:36:28 CEST 2012

On 2012-10-25, at 3:25 PM, Guido van Rossum <guido at python.org> wrote:
> On Thu, Oct 25, 2012 at 11:39 AM, Yury Selivanov
> <yselivanov.ml at gmail.com> wrote:

>> One idea: the scope of the problem is enormously big.  It may take
>> months/years to synchronize all ideas and thoughts by just communicating
>> ideas over mail list without a concrete thing and subject to discuss.
>> How about you/we create a repository with a draft implementation of
>> scheduler/io loop/coroutines engine and we simply start tweaking an
>> discussing that particular design?  That way people will see where
>> to start the discussion, what's done, and some will even participate?
>> The goal is not to write a production-quality software, but rather to
>> have a common place to discuss/try things/benchmark etc.  I'm not sure,
>> but maybe places like bitbucket, where you can have a wiki, issues, and
>> the actual code is a better place, than a mail-list.
> I am currently working on code. Steve Dower has also said he's going
> to write some code. I'm just not quite ready to show my code (I need
> to do a few more iterations on each component). As long as I can use
> Mercurial I'm happy; bitbucket or Google Code Hosting both work fine
> for me.

OK.  Let's wait until we have a somewhat stable platform to work with.

>> Is it (roughly) how you want it all to look like?  I.e. using 'yield' to
>> send a future/task to the scheduler, and 'yield from' to delegate?
> I think that's the style that Steve Dower prefers. Greg Ewing would
> rather see all public APIs use yield from, and reserve plain yield
> exclusively as an implementation detail of the scheduler. In my own
> experimental code I am using Greg's style and it is working out great.
> My main reason for taking a hard stance on this is that it would
> otherwise be too confusing for users -- should they use yield, yield
> from, or a plain call? I'd like to tell them "if it blocks, use yield
> from".
> BTW, if you haven't read Greg's introduction to this style, here it is
> -- worth reading!
> http://www.cosc.canterbury.ac.nz/greg.ewing/python/tasks/SimpleScheduler.html
>> If I guessed correctly, and that's how you envision it, I have a question:
>> What if you decide to refactor 'Socket.sendall' to be a coroutine?
>> In that case you'd want users to call it 'yield from Socket.sendall', and
>> not 'yield Socket.sendall'.
> That's why using yield from all the way is better!

Yes, that now makes sense!  
I'll definitely take a look at Greg's article.


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