valid uses of shared

[Steven Schveighoffer]

On Sat, 09 Jun 2012 08:31:01 -0400, Mike Wey <mike-wey at example.com> wrote:

> On 06/09/2012 04:01 AM, mta`chrono wrote:
>> Would this be legal?
>>
>> class A
>> {
>>       private static shared int counter; // shared across all instances
>>
>>       this()
>>       {
>>            auto i = ++counter;
>>            pragma(msg, typeof(i)); // prints int
>>       }
>> }
>>
>
> Would it also be legal if the variable wasn't static?

No.

> int opApply(int delegate(ref Pixels) dg)
> {
>      shared(int) progress;
>
>      foreach ( row; taskPool.parallel(iota(extent.y, extent.y +  
> extent.height)) )
>      {
>          int result = dg(Pixels(image, extent.x, row, extent.width, 1));
>
>          if ( result )
>               return result;
>
>          if ( image.monitor !is null )
>          {
>              atomicOp!"+="(progress, 1);
>              image.monitor()("ImageView/" ~ image.filename, progress,  
> extent.height);
>          }
>      }
>      return 0;
> }

AFAIK, if you removed shared from progress, it would work.  I don't think  
std.parallel is as strict as std.concurrency (and for pretty good reason).

I think a better way to mark progress is to make it an atomic integer type  
(like Artur has developed).

-Steve