在VB.net中显式添加/删除事件

Imports System.Runtime.CompilerServices
...
    Private propchanged As PropertyChangedEventHandler

    Public Custom Event PropertyChanged As PropertyChangedEventHandler

        <MethodImpl(MethodImplOptions.Synchronized)> _
        AddHandler(ByVal value As PropertyChangedEventHandler)
            propchanged = DirectCast([Delegate].Combine(propchanged,value),PropertyChangedEventHandler)
        End AddHandler

        <MethodImpl(MethodImplOptions.Synchronized)> _
        RemoveHandler(ByVal value As PropertyChangedEventHandler)
            propchanged = DirectCast([Delegate].Remove(propchanged,PropertyChangedEventHandler)
        End RemoveHandler

        RaiseEvent(ByVal sender As Object,ByVal e As System.ComponentModel.PropertyChangedEventArgs)
            Dim handler = propchanged
            If handler IsNot Nothing Then handler(sender,e)
        End RaiseEvent
    End Event