Implement async/await using Fiber

[Ali Çehreli via Digitalmars-d-learn]

On 05/19/2016 12:57 PM, Yuxuan Shui wrote:
> I find this difficult because I can't passing data via
> Fiber.yield/Fiber.call pair. e.g. I want something like:
>
> void fiberFunc() {
>     //Add some file descriptor to main loop
>     string y = Fiber.yield();
>     writeln(y);
> }
>
> auto f = new Fiber(&fiberFunc);
> f.call();
> mainloop {
>     if (fd_readable)
>        f.call(fd.rawRead());
> }
>
> I can probably using a derived fiber class and pass the result via class
> members, but that seems clumsy and not very general. Any ideas?
>

You can use a delegate that takes a ref parameter:

import std.stdio;
import core.thread;

void fiberFunc(ref string y) {
     y = "produced_by_fiberFunc";
     Fiber.yield();
}

void main() {
     string data;
     auto f = new Fiber(() => fiberFunc(data));
     f.call();
     writefln("Writing in main: %s", data);
}

Prints:

Writing in main: produced_by_fiberFunc

Also see std.concurrency.Generator. Both methods appear here:

   http://ddili.org/ders/d.en/fibers.html

Ali