Yarko Tymciurak kirjoitti 09.06.2017 klo 09:19:
On Fri, Jun 9, 2017 at 12:48 AM Nathaniel Smith <n...@pobox.com
<mailto:n...@pobox.com>> wrote:
On Thu, Jun 8, 2017 at 3:32 PM, manuel miranda
<manu.miran...@gmail.com <mailto:manu.miran...@gmail.com>> wrote:
> Hello everyone,
>
> After using asyncio for a while, I'm struggling to find
information about
> how to support both synchronous and asynchronous use cases for
the same
> library.
>
> I.e. imagine you have a package for http requests and you want
to give the
> user the choice to use a synchronous or an asynchronous
interface. Right now
> the approach the community is following is creating separate
libraries one
> for each version. This is far from ideal for several reasons,
some I can
> think of:
>
> - Code duplication, most of the functionality is the same in
both libraries,
> only difference is the sync/async behaviors
> - Some new async libraries lack functionality compared to their sync
> siblings. Others will introduce bugs that the sync version
already solved
> long ago, etc.
> - Different interfaces for the user for the same exact
functionality.
>
> In summary, in some cases it looks like reinventing the wheel.
So now comes
> the question, is there any documentation, guide on what would be
best
> practice supporting this kind of duality?
I would say that this is something that we as a community are still
figuring out. I really like the Sans-IO approach, and it's a really
valuable piece of the solution, but it doesn't solve the whole problem
by itself - you still need to actually do I/O, and this means things
like error handling and timeouts that aren't obviously a natural fit
to the Sans-IO approach, and this means you may still have some tricky
code that can end up duplicated. (Or maybe the Sans-IO approach can be
extended to handle these things too?) There are active discussions
happening in projects like urllib3 [1] and packaging [2] about what
the best strategy to take is. And the options vary a lot depending on
whether you need to support python 2 etc.
If you figure out a good approach I think everyone would be interested
to hear it :-)
Just to leave this breadcrumb here - I've said this before, but not
thought in depth about it a lot, but pretty sure that in something
like Python4, async needs to become "first class citizen," that is
from the inside out, right in the bowels of the repl loop.
Python 4 will be nothing more than the next minor release after 3.9.
Because Guido hates double digit minor versions :)
If async is the default, and synchronous calls just a special case
(e.g. single-task async), then I'd expect two things (at least):
developers would have an easier time, make fewer mistakes in async
programming (the language would handle more), and libraries would be
unified as async & sync would be the same.
Are you suggesting the removal of the "await", "async with" and "async
for" structures? Those were added deliberately so developers can spot
the yield points in a coroutine function. Not having them would give us
something like gevent where you can never tell when your task is going
to be adjourned in favor of another.
Maybe there's something that would make this not make sense, but I'd
be really surprised. Larry's gil removal work intuitively seems an
enabler for this kind of (potential) work...
-y
-n
[1] https://github.com/shazow/urllib3/pull/1068#issuecomment-294422348
[2] Here's the same API implemented three different ways:
Using deferreds: https://github.com/pypa/packaging/pull/87
"traditional" sans-IO: https://github.com/pypa/packaging/pull/88
Using the "effect" library:
https://github.com/dstufft/packaging/pull/1
--
Nathaniel J. Smith -- https://vorpus.org
_______________________________________________
Async-sig mailing list
Async-sig@python.org <mailto:Async-sig@python.org>
https://mail.python.org/mailman/listinfo/async-sig
Code of Conduct: https://www.python.org/psf/codeofconduct/
_______________________________________________
Async-sig mailing list
Async-sig@python.org
https://mail.python.org/mailman/listinfo/async-sig
Code of Conduct: https://www.python.org/psf/codeofconduct/
_______________________________________________
Async-sig mailing list
Async-sig@python.org
https://mail.python.org/mailman/listinfo/async-sig
Code of Conduct: https://www.python.org/psf/codeofconduct/
