On Thu, Jul 18, 2024 at 10:55 AM Lénárd Szolnoki wrote:
>
> Widget foo(int x) {
> for (int i = 0; i < x; ++i) {
> auto w = Widget(i);
> if (w.some_observer()) {
> return w;
> }
> }
> return Widget(-1);
> }


enum Status { Success, Retry, Failure };

Widget foo(int const x)
{
    int i = 0;

    return construct_modify<Widget>(
        i, // passed by reference
        [&](auto &a) -> Status
        {
            if ( i++ >= x ) return Failure;
            if ( a.some_observer() ) return Success;
            return Retry;
         },
         [](void) -> Widget { return Widget(-1); }
     );
}