Closure/Stack-to-Heap Semantics

[downs]

dsimcha wrote:
> If I write a loop, and want to submit each iteration of that loop to its own
> thread, or to a thread pool or something, how do I get D to copy the current
> stack frame to the heap each time I use the delegate?  For example:
> 
> import std.thread, std.stdio, std.c.time;
> 
> void main() {
>     Thread[] myThreads = new Thread[100];
>     foreach(i; 0..100) {
>         auto T = new Thread({
>             sleep(1);  //Give i time to be incremented to 100.
>             writeln(i);
>             return 0;
>         });
>         T.start;
>         myThreads[i] = T;
>     }
>     foreach(T; myThreads) {
>         T.wait;
>     }
> }
> 
> This program prints out all 100's because by the time each thread is done
> sleeping, i = 100.  How do I make D copy the stack context each time I submit
> a delegate to a thread, in similar fashion to a closure?

This is how I'd do it with tools/1.0:

void main() {
  auto tp = new Threadpool(100);
  auto sem = new Semaphore;
  foreach (i; Range[0..100].endIncl) {
    tp.addTask(i /apply/ (int i) {
      sleep(1);
      writefln(i);
      sem.release;
    });
  }
  foreach (i; Range[0..100].endIncl)
    sem.acquire;
}

 (Untested)