Invercargill/src/lib/Promotions/Elements.vala

namespace Invercargill {
    public interface Elements : Enumerable<Element>, Sticky<Elements, Element> {

        public virtual Enumerable<T> elements_as<T>() {
            return select_where<T>((e, out r) => e.try_get_as<T>(out r));
        }

        public virtual Enumerable<T> assert_elements_as<T>() {
            return select<T>(e => e.assert_as<T>());
        }

    }

    private class ElementsPromotionImplementation : StickyProxyPromotion<Elements, Element>, Sticky<Elements, Element>, Elements {

        protected override Elements adhere (Enumerable<Element> enumerable) {
            return (Elements)new ElementsPromotionImplementation().wrap(enumerable);
        }

        protected override Elements passthrough () {
            return this;
        }

        public override bool can_wrap (GLib.Type element_type) {
            return element_type.is_a (typeof(Element));
        }



    }
}