Re: [Vala] Confusing closure behavior

[Wolfgang Mauer <wolfgang mauer kabelmail de>]

C#(Mono) would say

int[]indices={0};
foreach(variinindices)
{
i=999;<-- Error CS1656: Cannot assign to 'i' because it is a 'foreach 
iteration variable' (CS1656)
}


Am 09.04.19 um 11:23 schrieb Nor Jaidi Tuah:
> On Tue, 2019-04-09 at 08:25 +0200, Vivien Kraus wrote:
> > Digging a little deeper, I have some more confusion.  This makes the
> > for-loop and the foreach-loop behave differently.  What do you think
> > of:
> >
> > // capturing the for variable should capture a copy if the variable
> > is
> > // local to the for loop
> >
> > public delegate void Thunk();
> >
> > int main() {
> >        Thunk thunk = () => {};
> >        for (int i = 0; i < 1; i++) {
> >                thunk = () => {
> >                        stderr.printf ("%d = 0, right?\n", i);
> >                };
> >        }
> >        thunk ();
> >        int[] indices = { 0 };
> >        foreach (var i in indices) {
> >                thunk = () => {
> >                        stderr.printf ("%d = 0, right?\n", i);
> >                };
> >        }
> >        thunk ();
> >        return 0;
> > }
> I believe foreach pass the values inside the array.
> e.g.,
>
>     foreach (var i in indices) {
>        i = 999;
>     }
>
> will not change indices[0] at all. A more strict language
> will even forbid that "i = 999".
>
>
> Nice day
> Nor Jaidi Tuah
>
>
>
>
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