在knockout.js中创建一个脏标志绑定

我正在尝试创建一个绑定处理程序,它允许我跟踪绑定中使用的任何值是否已更改:

    *

    
        Text 1
        
    

到目前为止我尝试了以下内容:

ko.bindingHandlers.dirty = {
    init: function(element, valueAccessor, allBindingsAccessor, viewModel, bindingContext) {

        var counter = 0;
        var dirtyObservable = valueAccessor();
        var appliedBindings = false;

        var computed = ko.computed(function() {
            if (!appliedBindings) {
                // I was hoping this would subscribe all the used observables
                ko.applyBindingsToDescendants(bindingContext, element);
                appliedBindings = true;
            }
            // make sure subscribe is triggered by returning a new value
            return counter++; 
        });
        computed.subscribe(function() {
            dirtyObservable(true);
        });

        return { controlsDescendantBindings: true };
    }
};

我希望ko.applyBindingsToDescendants能订阅该容器内所有绑定中使用的observable.然而,情况似乎并非如此; 见http://jsfiddle.net/F3uMr/1/.

还有另一种方法来实现这一目标吗？或者为每个容器创建一个ViewModel然后使用脏标志会更好吗？