Here is a code:

import std.stdio, std.datetime, std.random, std.range, std.parallelism;


enum long numberOfSlaves = 2;


void myFunc( ref long countvar)
{


 countvar = 500;

  writeln( " value of countvar is  ", countvar);
}


void main()
{
long count1=0, count2=0;
alias typeof(task!(myFunc)(0L)) MyTask ;


//Possibility  1
 	MyTask[numberOfSlaves] tasks;
        tasks[0] = task!(myFunc)(count1);
        taskPool.put(tasks[0]);
	tasks[1] = task!(myFunc)(count2);
        taskPool.put(tasks[1]);
       for (long cc =0; cc < numberOfSlaves; cc++)
       tasks[cc].yieldForce();
//Possibility  2
      //myFunc(count1);
      //myFunc(count2);

   writeln( " value of count1 and count2 are ", count1, " ", count2);
}


Possibility  1: Here, I wanted to pass a value by reference to myFunc, but when I read that value in main function, its value is not changed at all?

Possibility 2: It does what I want.

So, how to properly use the taskPool, so that pass by reference works.

Uncomment/comment Possibility 1 or 2 to see the output.

On 03/01/2013 06:51 PM, Sparsh Mittal wrote:

> Possibility 1: Here, I wanted to pass a value by reference to myFunc,
> but when I read that value in main function, its value is not changed at
> all?

This is a known issue and is documented in the std.parallelism module:

  http://dlang.org/phobos/std_parallelism.html#.Task

"BUGS: Changes to ref and out arguments are not propagated to the
call site, only to args in this struct."

You can pass a pointer:

void myFunc(long *countvar)
{
    *countvar = 500;
    writeln( " value of countvar is  ", *countvar);
}

// ...

    tasks[0] = task!myFunc(&count1);

Ali

Thanks a lot for your reply.