Question

在C＃中如果我想创建一个“自定义事件”，你可以这样做：

private EventHandler _MyEvent;
Public Event EventHandler MyEvent 
{
   add{ _MyEvent += value; }
   remove{ _MyEvent -= Value; }
}
protected void RaiseMyEvent()
{
   if(_MyEvent != nul)
      _MyEvent(this, EventArgs.Empty);
}

在VB中，这不是那么简单，我也无法在网上找到任何帮助。这不起作用：

private _MyEvent as EventHandler
Public Custom Event MyEvent as EventHandler
   AddHandler(ByVal value as EventHandler)
      _MyEvent += value 'does not work
      addhandler _MyEvent, value 'does not work
      [Delegate].Combine(_MyEvent, value) '_MyEvent still nothing
   End AddHandler
   RemoveHandler(ByVal value as EventHandler)
      'Same kind of stuff here
   End RemoveHandler
   RaiseEvent(sender as Object, e as EventArgs)
      if(_MyEvent IsNot Nothing) Then '_MyEvent is always nothing
         _MyEvent.Invoke(sender, e)
      End If
   End RaiseEvent
End Event

请帮忙。

Answer 1

VB为你做了很多工作。

简单地宣布一个事件：

Public Event DidSomething(sender as object, e as EventArgs)

然后在代码中的任何地方，调用下降的提升事件

RaiseEvent DidSomething(me, EventArgs.Empty)

Answer 2

委托是不可变的，因此方法“[Delegate] .Combine”返回新委托，但不修改参数。所以你需要：

_MyEvent = [Delegate].Combine(_MyEvent, value)

Answer 3

...现在，如果您（或其他任何人在询问）如何创建处理引发事件的方法，基于“DidSomething”示例，您将按以下方式执行此操作：< / p>

Private Sub NowDoSomething(sender As Object, e As EventArgs) Handles Me.DidSomething
   'Code for Event here
End Sub

“自定义事件”如何在VB.Net中运行？

3 个答案: