模拟C#的事件添加和删除

  1 using System;
  2 using System.Collections.Generic;
  3 using System.Linq;
  4 using System.Text;
  5 using System.Threading;
  6 using System.Threading.Tasks;
  7 
  8 namespace ExpForEvent001
  9 {
 10     public sealed class EventKey : Object { }
 11 
 12     public sealed class EventSet
 13     {
 14         private readonly Dictionary<EventKey, Delegate> m_events = new Dictionary<EventKey, Delegate>();
 15 
 16         public void Add(EventKey eventKey, Delegate handler)
 17         {
 18             Monitor.Enter(m_events);
 19             Delegate d;
 20             m_events.TryGetValue(eventKey, out d);
 21             m_events[eventKey] = Delegate.Combine(d, handler);//Here we used Combine
 22             Monitor.Exit(m_events);
 23         }
 24 
 25         public void Remove(EventKey eventKey, Delegate handler)
 26         {
 27             Monitor.Enter(m_events);
 28             Delegate d;
 29             if (m_events.TryGetValue(eventKey, out d))
 30             {
 31                 d = Delegate.Remove(d, handler);
 32 
 33                 if (d != null) m_events[eventKey] = d;
 34                 else m_events.Remove(eventKey);
 35             }
 36             Monitor.Exit(m_events);
 37         }
 38 
 39         public void Raise(EventKey eventKey, Object sender, EventArgs e)
 40         {
 41             Delegate d;
 42             Monitor.Enter(m_events);
 43             m_events.TryGetValue(eventKey, out d);
 44             Monitor.Exit(m_events);
 45 
 46             if (d != null)
 47             {
 48                 d.DynamicInvoke(new Object[]{ sender, e });
 49             }
 50         }
 51     }
 52 
 53     public class FooEventArgs : EventArgs { }
 54 
 55     public class TypeWithLotsOfEvents
 56     {
 57         public readonly EventSet m_eventSet = new EventSet();
 58 
 59         protected EventSet EventSet { get { return m_eventSet; } }
 60 
 61         #region Support Foo Event
 62 
 63         protected static readonly EventKey s_fooEventKey = new EventKey();
 64 
 65         public event EventHandler<FooEventArgs> Foo
 66         {
 67             add { m_eventSet.Add(s_fooEventKey, value); }
 68             remove { m_eventSet.Remove(s_fooEventKey, value); }
 69         }
 70 
 71         protected virtual void OnFoo(FooEventArgs e)
 72         {
 73             m_eventSet.Raise(s_fooEventKey, this, e);
 74         }
 75 
 76         public void SimulateFoo() { OnFoo(new FooEventArgs()); }
 77 
 78         #endregion
 79     }
 80 
 81     class Program
 82     {
 83         static void Main(string[] args)
 84         {
 85             TypeWithLotsOfEvents twle = new TypeWithLotsOfEvents();
 86 
 87             twle.Foo += HandleFooEvent1;
 88             twle.Foo += HandleFooEvent2;
 89 
 90             twle.SimulateFoo();
 91         }
 92 
 93         private static void HandleFooEvent1(object sender, FooEventArgs e)
 94         {
 95             Console.WriteLine("Handling Foo Event here...");
 96         }
 97 
 98         private static void HandleFooEvent2(object sender, FooEventArgs e)
 99         {
100             Console.WriteLine("Handling Foo Event here2...");
101         }
102     }
103 }