[Python-ideas] yield from multiple iterables (was Re: The async API of the future: yield-from)

[Guido van Rossum]

On Fri, Oct 19, 2012 at 5:05 AM, Christian Tismer <tismer at stackless.com> wrote:
> On 19.10.12 07:15, Greg Ewing wrote:
>>
>> Christian Tismer wrote:
>>
>>> - generators are able to free the stack, when they yield. But when they
>>>    are active, they use the full stack. At least when I follow the
>>> pattern
>>>    "generator is calling sub-generator".
>>>    A deeply nested recursion is therefore something to avoid. :-(
>>
>>
>> Only if yield-from chains aren't optimised the way they
>> used to be.
>
>
> Does that mean a very deep recursion would be efficient?

TBH, I am not interested in making very deep recursion work at all. If
you need that, you're doing it wrong in my opinion.

> I'm trying to find that change in the hg history right now.
>
> Can you give me a hint how your initial implementation
> works, the initial patch source?
>>
>>
>> ...
>>
>>> But this function that wants to
>>> switch needs to pass the fact that it wants to switch, plus the target
>>> somewhere. As I understood it, I would need to yield that to the
>>> driver function.
>>
>>
>> You understand incorrectly. In my scheduler, the yields
>> don't send or receive values at all. Communicating with the
>> scheduler, for example to tell it to allow another task to
>> run, is done by calling functions. A yield must be done to
>> actually allow a switch, but the yield itself doesn't send
>> any information.
>
>
> I have studied that yesterday already in depth and like that quite much.
> It is probably just the problem that I had with generators from their
> beginning.
>
>
> --
> Christian Tismer             :^)   <mailto:tismer at stackless.com>
> Software Consulting          :     Have a break! Take a ride on Python's
> Karl-Liebknecht-Str. 121     :    *Starship* http://starship.python.net/
> 14482 Potsdam                :     PGP key -> http://pgp.uni-mainz.de
> phone +49 173 24 18 776  fax +49 (30) 700143-0023
> PGP 0x57F3BF04       9064 F4E1 D754 C2FF 1619  305B C09C 5A3B 57F3 BF04
>       whom do you want to sponsor today?   http://www.stackless.com/
>
> _______________________________________________
> Python-ideas mailing list
> Python-ideas at python.org
> http://mail.python.org/mailman/listinfo/python-ideas



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