使用函数的BeginInvoke？

Question

这个子工作正常:

Private Sub UpdateInfo(ByVal text As String, ByVal timeStamp As DateTime)
    If Me.lstStatus.Dispatcher.Thread Is System.Threading.Thread.CurrentThread Then
        ' Do stuff with 
    Else
        Me.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Send, New Action(Of String, DateTime)(AddressOf UpdateInfo), text, timeStamp)
    End If
End Sub

但是这个功能没有:

Private Function UpdateInfo(ByVal text As String, ByVal timeStamp As DateTime) As ListItem
    If Me.lstStatus.Dispatcher.Thread Is System.Threading.Thread.CurrentThread Then
        Dim l As New ListItem
        ' Do stuff with 
        Return l
    Else
        Me.Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Send, New Action(Of String, DateTime)(AddressOf UpdateInfo), text, timeStamp)
        ' Above line doesn't return anything??
    End If
End Function

如何在上面的函数中返回我的listitem？

谢谢!!!!!

:) Mojo

Answer 1

Dispatcher.BeginInvoke()是一种即发即弃的方法,委托目标稍后在UI线程上运行.在你的情况下,这还不够好,你需要等到目标运行,这样你才能获得返回值.改为使用Invoke()方法:

 Return DirectCast(Me.Dispatcher.Invoke(..), ListItem)

并使用Func而不是Action.或者AddressOf,更"自然"的VB.NET方式.