域驱动设计 – AutoFac IoC,DDD和存储库间依赖关系

您可以按如下方式编写代码：

public class Observable<T>:IDisposable
{
   private T instance;
   public T Instance
   {
      get{return instance;}
      set{
         instance = value;
         var handlers = ReferenceChanged;
         if(handlers != null) handlers(this,instance);
   }

   public static implicit operator T(Observable<T> obs)
   {
      return obs.Instance;
    }

   //DO NOT attach anonymous delegates or lambdas to this event,or you'll cause a leak
   public event EventHandler<T> ReferenceChanged;

   public void Dispose()
   {
      var handlers = ReferenceChanged;
      if(handlers != null) handlers(this,null);
      foreach(var handler in handlers) ReferenceChanged -= handler;
   }
}

public class Rep<T>
{
   private Dictionary<T,Observable<T>> observableDictionary = new Dictionary<T,Observable<T>>();

   ...
   public Observable<T> GetObservableFactory(Predicate<T> criteria)
   {
      //criteria should test only uniquely-identifying information
      if(observableDictionary.Keys.Any(criteria))
         return observableDictionary[observableDictionary.Keys.First(criteria)];
      else
      {
         //TODO: get object from source according to criteria and set to variable queryResult
         var observable = new Observable<T>{Instance = queryResult};
         observableDictionary.Add(queryResult,observable);
         return observable;
      }
   }
}

...

var observableA = myRepA.GetObservable(myCriteria);
observableA.ReferenceChanged += DoSomethingWhenReferenceChanges;

现在,如果更改了内部引用,或者处理了observable(它也处理了内部引用),将通知使用代码.为了使observable还通知消费代码,如果As的变化,A的子引用本身必须是可观察的,则触发由Observable< T>处理的事件.它将通过ReferenceChanged或更具体的处理程序(例如InstanceDataChanged)(或任何你想要调用它)来“冒泡”它.