[Python-ideas] An async facade? (was Re: [Python-Dev] Socket timeout and completion based sockets)

Guido van Rossum guido at python.org
Fri Nov 30 20:30:34 CET 2012

On Fri, Nov 30, 2012 at 11:27 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> On Fri, 30 Nov 2012 11:04:09 -0800
> Guido van Rossum <guido at python.org> wrote:
>> Futures or callbacks, that's the question...
>> Richard and I have even been considering APIs like this:
>> res = obj.some_call(<args>)
>> if isinstance(res, Future):
>>     res = yield res
>> or
>> res = obj.some_call(<args>)
>> if res is None:
>>     res = yield <magic>
>> where <magic> is some call on the scheduler/eventloop/proactor that
>> pulls the future out of a hat.
>> The idea of the first version is simply to avoid the Future when the
>> result happens to be immediately ready (e.g. when calling readline()
>> on some buffering stream, most of the time the next line is already in
>> the buffer); the point of the second version is that "res is None" is
>> way faster than "isinstance(res, Future)" -- however the magic is a
>> little awkward.
> This premature optimization looks really ugly to me. I'm strongly -1
> on both idioms.

Read my explanation in my response to Steve.

--Guido van Rossum (python.org/~guido)

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