事件注冊與潛在隱患

  class EnterpriseComponent
  {
    public event EventHandler OnEvent;

    ~EnterpriseComponent()
    {
      Console.WriteLine("EnterpriseComponent Destroy...");
    }

    public void DoEvent()
    {
      if (OnEvent != null)
        OnEvent(this, EventArgs.Empty);
    }
  }

  class Client
  {
    ~Client()
    {
      Console.WriteLine("Client Destroy...");
    }

    public void OnEvent(object sender, EventArgs e)
    {
      Console.WriteLine("Event...");
    }
  }

  class Program
  {
    static void Main(string[] args)
    {
      EnterpriseComponent eco = new EnterpriseComponent();
      Client client = new Client();

      // 注冊事件
      eco.OnEvent += new EventHandler(client.OnEvent);

      // 執行事件
      eco.DoEvent();

      // 模擬Client超出作用範圍，等待垃圾回收。
      client = null;

      // 執行垃圾回收
      Console.WriteLine("--GC Strat ---------------");
      GC.Collect();
      Console.WriteLine("--GC End------------------");
    }
  }

Event...
--GC Strat ---------------
--GC End------------------

    static void Main(string[] args)
    {
      EnterpriseComponent eco = new EnterpriseComponent();
      Client client = new Client();

      // 注冊事件
      eco.OnEvent += new EventHandler(client.OnEvent);

      // 執行事件
      eco.DoEvent();

      eco.OnEvent -= new EventHandler(client.OnEvent); // <----- 添加的代碼，取消事件注冊！！！

      // 模擬Client超出作用範圍，等待垃圾回收。
      client = null;

      // 執行垃圾回收
      Console.WriteLine("--GC Strat ---------------");
      GC.Collect();
      Console.WriteLine("--GC End------------------");
    }

Event...
--GC Strat ---------------
Client Destroy...
--GC End------------------