Actually, this is Luca's code (the coroutine-based generator).
(I am the guilty party to blame for the naive idea to try to add threads to
it : I had the Goroutine/channel concept of Go in mind and was trying to
emulate it by attempting to combine Luca's generator with threads).
:)
Serge.
On Wed, Jul 13, 2011 at 3:02 PM, Jim Peters <j...@uazu.net> wrote:
> Serge Hulne wrote:
> > Here is a further development of the idea of Luca Bruno about a Vala
> > implementation for Generators:
> >
> > Simulating Go's goroutines and channels in Vala:
> >
> > Basically the idea is to start as many threads as needed (which play the
> > role of Go' goroutines) and to recuperate their output from a "Generator"
> > (which plays the role of the "Go" channel form which the result from a
> given
> > thread can be pulled):
>
> To clarify after all the confusion (partly my fault -- sorry):
>
> - Luco's Generator doesn't need threads, and it doesn't need a main
> loop either, even though it is using 'async'
>
> - The whole thing runs in a single thread
>
> A few thoughts:
>
> - 'async' is really powerful in Vala, but also quite hard to
> understand. (I wish I could find a high-level design document
> explaining async in GIO.)
>
> - Its implementation of coroutines doesn't require another stack, it
> holds its state in a private data structure. When it does a 'yield'
> it returns to the caller, and when it is next given control, it
> resumes the previous point of execution using a switch and 'goto'.
>
> - Probably it could all go a lot faster if less housekeeping was going
> on, but I haven't seen Go's implementation either, so who knows how
> it compares. Anyway, Vala always puts functionality first and
> optimisation second, which suits people who want to get the job done
> now instead of waiting for the ultimate language to arrive, so that
> seems okay.
>
> Attached is a version of Serge's code with all the thread stuff cut
> out, which still works.
>
> Jim
>
> /////////////////////////////////
> using Posix;
>
> abstract class Generator<G> {
> private bool consumed;
> private unowned G value;
> private SourceFunc callback;
>
> public Generator () {
> helper ();
> }
>
> private async void helper () {
> yield generate ();
> consumed = true;
> }
>
> protected abstract async void generate ();
>
> protected async void feed (G value) {
> this.value = value;
> this.callback = feed.callback;
> yield;
> }
>
> public bool next () {
> return !consumed;
> }
>
> public G get () {
> var result = value;
> callback ();
> return result;
> }
>
> public Generator<G> iterator () {
> return this;
> }
> }
>
> class IntGenerator : Generator<int> {
> protected override async void generate () {
> for (int i=0; i < 10; i++) {
> if (i%2 ==0) yield feed (i);
> }
> }
> }
>
> class IntGenerator_1 : Generator<int> {
> protected override async void generate () {
> for (int i=0; i < 10; i++) {
> if (i%2 !=0) yield feed (i);
> }
> }
> }
>
> int main(string[] args) {
>
> var gen = new IntGenerator();
> var gen_1 = new IntGenerator_1();
>
> print("\n\nResults computed in first generator\n");
>
> var i=0;
> foreach (var item in gen) {
> if (i<10) Posix.stdout.printf("%i\n", item);
> i++;
> }
>
> print("\n\nResults computed in the second generator\n\n");
>
> i=0;
> foreach (var item in gen_1) {
> if (i<10) Posix.stdout.printf("%i\n", item);
> i++;
> }
>
> return 0;
> }
>
> /////////////////////////////////
>
> --
> Jim Peters (_)/=\~/_(_) j...@uazu.net
> (_) /=\ ~/_ (_)
> Uazú (_) /=\ ~/_ (_) http://
> in Peru (_) ____ /=\ ____ ~/_ ____ (_) uazu.net
>
_______________________________________________
vala-list mailing list
vala-list@gnome.org
http://mail.gnome.org/mailman/listinfo/vala-list
