(semi) stackless python

John DeWeese deweese at usc.edu
Thu Dec 20 22:16:41 CET 2001


>  The new generators in Python2.2 implement semi-coroutines, not
> full coroutines:  the limitation is that they always return to
> their caller -- they can't take an arbitrary continuation as
> a return target.
>
>  So you can't do everything you can do in Stackless, or at least,
> you can't do it the same way. I'm not sure what the limitations
> are yet, but you might be surprised with what you CAN do.
>  If all the generator objects yield back to the same 'driver'
> procedure, then you can do a sort of cooperative multithreading.
> In that case, you're executing the generators for their side
> effects -- the value returned by yield may be unimportant except
> perhaps as a status code.
>
> [ See also Tim Peters' post on the performance advantages of
>   generators -- you only parse args once for many generator
>   calls, and you keep and reuse the same stack frame. So I
>   believe you get some of the same benefits of Stackless
>   microthreads. ]
>
> Maybe I can find the time to post an example of what I mean.
> In the mean time, some previous posts on generators might give
> you some ideas.

Thanks, I will do some research on generators. If they are sufficient, I
would be able to stick to the latest python.

  - John





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