vb.net 4.0 模拟支持4.5 task.run

TaskEx.Run是自定义的方法，为了使.net4.0也支持.net4.5的 task run语法。

代码未经测试

 Class TaskEx　　'4.0模拟 task.run

        Public Shared Function Run(ByVal action As Action) As Task
            Dim tcs = New TaskCompletionSource(Of Object)()
            Dim t As New Thread(Sub()
                                    Try
                                        action()
                                        tcs.SetResult(Nothing)
                                    Catch ex As Exception
                                        tcs.SetException(ex)
                                    End Try
                                End Sub) With {.IsBackground = True}
            t.Start()

            Return tcs.Task
        End Function

        Public Shared Function Run(Of TResult)(ByVal [function] As Func(Of TResult)) As Task(Of TResult)
            Dim tcs = New TaskCompletionSource(Of TResult)()
            Dim t As New Thread(Sub()
                                    Try
                                        tcs.SetResult([function]())
                                    Catch ex As Exception
                                        tcs.SetException(ex)
                                    End Try
                                End Sub) With {.IsBackground = True}
            t.Start()
            Return tcs.Task
        End Function

        Public Shared Function Delay(ByVal milliseconds As Integer) As Task
            Dim tcs = New TaskCompletionSource(Of Object)()
            Dim timer = New System.Timers.Timer(milliseconds) With {
            .AutoReset = False
        }
            AddHandler timer.Elapsed, Sub()
                                          timer.Dispose()
                                          tcs.SetResult(Nothing)
                                      End Sub
            timer.Start()
            Return tcs.Task
        End Function
    End Class