x.js

var set = Set()
    , sorted = sortable()

set.on("add", function (obj) {
    var place = sorted.create()
        , widget = Widget(obj, place)
        
    widget.on("change", place.updateValue)

    place.updateValue(widget.value())
})

function Widget(obj, place) {
    var elem = makeElement()
        , widget = new EventEmitter()

    databind(elem, obj)

    place.append(elem)

    obj.on("end", function () {
        place.destroy()
    })

    obj.on("changes", function (changes) {
        if (changes.value) {
            widget.emit("change", changes.value)
        }
    })

    widget.value = function () {
        return obj.get("value")
    }

    return widget
}