• workman (13/13) Jan 11 2022 I need a solution to create closures on scope.
• Dennis (2/3) Jan 11 2022 Make sure `doTask` takes a `scope` delegate.
• workman (15/18) Jan 11 2022 Thanks, after add scope into doTask this work.
• workman (3/6) Jan 11 2022 To simple put, If the doTask is execute in other thread, do I
• workman (8/11) Jan 11 2022 To simple the question further:
• bauss (7/19) Jan 12 2022 Let me change your analogy and perhaps it will answer your own
• workman (12/18) Jan 12 2022 Thanks for the example.

workman <workman gmail.com> writes:

I need a solution to create closures on scope.

The closures will access scope vars, but it's lifetime will be 
end before quit the scope.  So it cloud be create on stack like 
value type.


Is there a workaround to made this work ?

```d
{
   int i = 0;
   int err = doTask(()  nogc nothrow scope {
       i++;
   });
}
```

Dennis <dkorpel gmail.com> writes:

On Tuesday, 11 January 2022 at 11:56:39 UTC, workman wrote:
 Is there a workaround to made this work ?

Make sure `doTask` takes a `scope` delegate.

workman <workman gmail.com> writes:

On Tuesday, 11 January 2022 at 13:32:58 UTC, Dennis wrote:
 On Tuesday, 11 January 2022 at 11:56:39 UTC, workman wrote:
 Is there a workaround to made this work ?

 Make sure `doTask` takes a `scope` delegate.

Thanks, after add scope into doTask this work.


One more question:


The delegate in doTask is execute in a nogc nothrow native 
thread,  before goto doTask I yield fiber. when native thread 
work done I call the fiber to continue run it.


The fiber will never be touched before work done callback 
finished. The fiber always destroy after scope exit.

In the native thread I call the delegate closures, the closures 
runtime stack will use native thread stack since there is no 
fiber switch.  (bu it will read/write fiber stack vars), and all 
stack vars will be destroyed after delegate closures scope quit.


After modify fiber stack vars from native thread, then send 
message to D thread, D thread call fiber again,  from there it 
always access the updated fiber stack value?

workman <workman gmail.com> writes:

On Tuesday, 11 January 2022 at 13:32:58 UTC, Dennis wrote:
 On Tuesday, 11 January 2022 at 11:56:39 UTC, workman wrote:
 Is there a workaround to made this work ?

 Make sure `doTask` takes a `scope` delegate.

To simple put, If the doTask is execute in other thread, do I 
need some things like volatile for fiber stack var I?

workman <workman gmail.com> writes:

On Tuesday, 11 January 2022 at 13:32:58 UTC, Dennis wrote:
 On Tuesday, 11 January 2022 at 11:56:39 UTC, workman wrote:
 Is there a workaround to made this work ?

 Make sure `doTask` takes a `scope` delegate.

To simple the question further:

step 1) A thread send the pointer into thread B by message

step 2) Thread B modify pointer value

step 3) Thread B send message to let Thread A know the work is 
done

step 4) Thread A read the pointer and get the value.  (in here 
Thread A always read the value updated by Thread B? )

bauss <jj_1337 live.dk> writes:

On Tuesday, 11 January 2022 at 15:47:58 UTC, workman wrote:
 On Tuesday, 11 January 2022 at 13:32:58 UTC, Dennis wrote:
 On Tuesday, 11 January 2022 at 11:56:39 UTC, workman wrote:
 Is there a workaround to made this work ?

 Make sure `doTask` takes a `scope` delegate.

 To simple the question further:

 step 1) A thread send the pointer into thread B by message

 step 2) Thread B modify pointer value

 step 3) Thread B send message to let Thread A know the work is 
 done

 step 4) Thread A read the pointer and get the value.  (in here 
 Thread A always read the value updated by Thread B? )

Let me change your analogy and perhaps it will answer your own 
question.

step 1) Person A shares a piece of paper with Person B
step 2) Person B writes something on the piece of paper
step 3) Person B gives the piece of paper back to Person A
step 4) Person A reads the piece of paper

workman <workman gmail.com> writes:

On Wednesday, 12 January 2022 at 14:06:53 UTC, bauss wrote:
 Let me change your analogy and perhaps it will answer your own 
 question.

 step 1) Person A shares a piece of paper with Person B
 step 2) Person B writes something on the piece of paper
 step 3) Person B gives the piece of paper back to Person A
 step 4) Person A reads the piece of paper


Thanks for the example.

I am ask here because I think this cloud be the case:


0) thread A set fiber stack var X = 0;
1) thread A send pointer X to thread B
2) thread B read pointer X, modify the X = 1
3) thread B send finish message to thread A
4) thread A read pointer X, but load X from CPU cache L1, so the 
value still be 0


Thread A & B will never try modify X same time,  but cloud 
read/write value from/to CPU cache.

I am not sure if this cloud be the case here.