[Python-ideas] yield from multiple iterables (was Re: The async API of the future: yield-from)
Guido van Rossum
guido at python.org
Fri Oct 19 18:07:24 CEST 2012
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
>>> "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
> Christian Tismer :^) <mailto:tismer at stackless.com>
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