On Thu, Apr 23, 2015 at 3:27 PM, Wolfgang Langner
<tds333+py...@gmail.com> wrote:
>
>
> On Thu, Apr 23, 2015 at 12:35 PM, Paul Sokolovsky <pmis...@gmail.com> wrote:
>>
>> Hello,
>>
>> On Thu, 23 Apr 2015 12:18:51 +0300
>> Andrew Svetlov <andrew.svet...@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.
>
By `channels` do you mean something like `asyncio.Queue`? It requires
that producer and consumer should be separate tasks. Often it works
(with some performance penalty cost) but creating 2 tasks is not
always obvious way to solve problem.
> Also possible a function returning futures and yield in the loop with a
> sentinel.
A proposal looks like guess to avoid `for` loop and use `while` everywhere.
Just compare `while` loop:
it = iter(it)
while True:
try:
i = next(it)
process(i)
except StopIteration:
break
with `for` alternative:
for i in it:
process(i)
>
> All this goes the road down to a producer consumer pattern. Nothing more.
>
I think one of the most convenient consumer-producer pattern
implementation in Python is `for` loop and iterators concept. It's
sometimes too limited but works pretty well in 95% of use cases.
>
--
Thanks,
Andrew Svetlov
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