On Mon, 2011-06-20 at 17:37 -0700, Jim Nelson wrote:
> With async, the delegate *is* copied, you just don't see it in the
> Vala code. With an async method, when the thread of execution yields,
> the state of the function at that point is stored (copied or ref'd) in
> a context structure. When the thread of execution resumes later, the
> state is pulled back out and the function resumes.
Has that any bearing on the bug I mentioned in
my earlier email?
> I also get segmentation fault trying to pass
> a closure accessing local variables. The closure
> works if it doesn't access local vars.
>
> e.g.,
> var f = etc;
> async_func ( () => { fn (f);} );
>
> will crash trying to access f. Apparently
> the closure isn't properly constructed.
In the following example, the closure bug doesn't
lead to a crash. But it is apparent in the output.
Expected output:
hello
hello
hello
bye
Actual output:
hello
hello
(null)
bye
The code:
public class Foo : Object {
public delegate void DelegateType ();
async void f3 (DelegateType d) {
d ();
}
async void f2 (DelegateType d) {
d ();
yield f3 (d);
d (); // <----- x local to f1 has gone
stdout.printf ("bye\n");
}
void f1 () {
var x = "hello";
f2 (() => {stdout.printf ("%s\n", x);});
}
public static int main(string[] args) {
var foo = new Foo ();
foo.f1 ();
new MainLoop (null, false).run ();
return 0;
}
}
hand
Nor Jaidi Tuah
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