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  1. public class Program
  2. {
  3.     public static void Main(string[] args)
  4.     {
  5.         Program A = new Program();
  6.  
  7.         var oldR = new WeakReference(new ReceiverOld(A));
  8.         var newR = new WeakReference(new ReceiverNew(A));
  9.  
  10.         A.RaiseTestEvent(); //First
  11.  
  12.         //Exec GC
  13.         GC.Collect();
  14.         GC.WaitForPendingFinalizers();
  15.         GC.Collect();
  16.  
  17.         A.RaiseTestEvent(); //Second
  18.  
  19.         //--Result --
  20.         //
  21.         // ReceiverOld Received !
  22.         // ReceiverNew Received !
  23.         // ReceiverOld Received !
  24.         //
  25.  
  26.         Console.ReadLine();
  27.     }
  28.  
  29.     private void RaiseTestEvent()
  30.     {
  31.         var handler = TestEvent;
  32.         if (handler != null)
  33.         {
  34.             handler(this, new RoutedEventArgs());
  35.         }
  36.     }
  37.  
  38.     public event RoutedEventHandler TestEvent;
  39. }
  40.  
  41. //Normal Event Receiver Class
  42. public class ReceiverOld
  43. {
  44.     public ReceiverOld(Program b)
  45.     {
  46.         b.TestEvent += OnTestEvent;
  47.     }
  48.  
  49.     void OnTestEvent(object sender, RoutedEventArgs e)
  50.     {
  51.         Console.WriteLine("ReceiverOld Received ! ");
  52.     }
  53. }
  54.  
  55. //Event Receiver Class With LivetWeakEventListener
  56. public class ReceiverNew
  57. {
  58.     LivetWeakEventListener _listener;//strong reference of listener
  59.  
  60.     public ReceiverNew(Program b)
  61.     {
  62.         _listener = new LivetWeakEventListener(
  63.             h => new RoutedEventHandler(h),//h is EventHandler
  64.             h => b.TestEvent += h, //h is RoutedEventHandler
  65.             h => b.TestEvent -= h, //h is RoutedEventHandler
  66.             OnTestEvent);
  67.     }
  68.  
  69.     void OnTestEvent(object sender, System.Windows.RoutedEventArgs e)
  70.     {
  71.         Console.WriteLine("ReceiverNew Received ! ");
  72.     }
  73. }
  74.  
  75. public class LivetWeakEventListener<THandler, TEventArgs> : IDisposable where TEventArgs : EventArgs
  76. {
  77.     private bool _disposed = false;
  78.  
  79.     private EventHandler<TEventArgs> _handler;
  80.     private THandler _resultHandler;
  81.     private Action<THandler> _remove;
  82.  
  83.     private static void ReceiveEvent(WeakReference listenerWeakReference, object sender, TEventArgs args)
  84.     {
  85.         var listener = listenerWeakReference.Target as LivetWeakEventListener<THandler, TEventArgs>;
  86.  
  87.         if (listener != null)
  88.         {
  89.             var handler = listener._handler;
  90.  
  91.             if (handler != null)
  92.             {
  93.                 handler(sender, args);
  94.             }
  95.         }
  96.     }
  97.  
  98.     private static THandler GetStaticHandler(WeakReference listenerWeakReference, Func<EventHandler<TEventArgs>, THandler> conversion)
  99.     {
  100.         return conversion((sender, e) => ReceiveEvent(listenerWeakReference, sender, e));
  101.     }
  102.  
  103.  
  104.     public LivetWeakEventListener(Func<EventHandler<TEventArgs>, THandler> conversion, Action<THandler> add, Action<THandler> remove, EventHandler<TEventArgs> handler)
  105.     {
  106.         if (conversion == null) throw new ArgumentNullException("conversion");
  107.         if (add == null) throw new ArgumentNullException("add");
  108.         if (remove == null) throw new ArgumentNullException("remove");
  109.         if (handler == null) throw new ArgumentNullException("handler");
  110.  
  111.         _handler = handler;
  112.         _remove = remove;
  113.  
  114.         _resultHandler = GetStaticHandler(new WeakReference(this), conversion);
  115.  
  116.         add(_resultHandler);
  117.     }
  118.  
  119.     public void Dispose()
  120.     {
  121.         Dispose(true);
  122.         GC.SuppressFinalize(this);
  123.     }
  124.  
  125.     protected virtual void Dispose(bool disposing)
  126.     {
  127.         if (_disposed) return;
  128.  
  129.         if (disposing)
  130.         {
  131.             _remove(_resultHandler);
  132.         }
  133.         _disposed = true;
  134.     }
  135. }
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https://ideone.com/wvREw
language:
C# (gmcs 5.20.1)
created:
12 years ago
visibility:
public

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