How to insert AdxRtList call in synchronous code?

Hi I am following the tutorial COM APIs for use in Microsoft Office and looking at Tutorial 2 AdxRtList. I understand that after the function is called with .StartUpdates in myRtGetExample then the result is returned asynchronously via callback to the myRtGet_OnImage function. I can see this might be appropriate if e.g. updating a spreadhsheet while you keep working in it. But if you are running some code and need the AdxRtList result BEFORE proceeding any further, how do you "make it synchronous"? I have stumbled on something which seems to work but don't know if it's the correct approach. The idea is to have a Boolean module level variable called task_finished_ which I set to false before the AdxRtList call and then loop after the call until task_finished_ = True. Meanwhile the callback myRtGet_OnImage sets task_finished_ = True before exiting.

Dim WithEvents myRTGet As AdfinXRtLib.AdxRtList

Private task_finished_ As Boolean

Sub myRtGetExample()

  task_finished_ = False

  Set myRTGet = CreateAdxRtList()

  With myRTGet

    Source = "IDN"

    .RegisterItems "EUR=", "BID"

    .StartUpdates RT_MODE_IMAGE

  End With



  While Not task_finished_

    Sleep 1000

    DoEvents

    Wend

End Sub

Private Sub myRtGet_OnImage(ByVal DataStatus As AdfinXRtLib.RT_DataStatus)

  Debug.Print myRTGet.Value("EUR=", "BID")

  task_finished_ = True

End Sub

As I said, it seems to work but I don't know if that's the right way to do it or if there is a better approach ... Thanks