On Sat, 2011-07-23 at 15:22 +0800, Nor Jaidi Tuah wrote:
> Is there any technical reason why
> reference parameters are not supported for async methods?
> 
> My work around to this is simply to replace
>   async void foo (ref X x)  // cannot compile
> 
> with
>   async void foo (ClosureX cx)
> where Closure is
>   class ClosureX {
>      X x;
>   }
> 
> But why can't the compiler do this for us?
> I must be missing something.
> 
> hand
> Nor Jaidi Tuah

I assume that it is due to scoping:

async void foo (ref int i) {
  yield;
  i = 0;
  yield;
}

int j = 1;
foo.begin (ref j);


j is on the stack but foo will access it outside scope. You can use
pointers and take care about scoping/freeing as compiler cannot do it
for you:

async void foo (int *i) {
  yield;
  *i = 0;
  yield;
}

int j = 1;
foo.begin (&j, (obj, res) => {
    foo.end (res);
    assert (j == 0); // Ok - j still alive
});

Regards

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