Question

I’m sure it’s a simple problem. I read from serial port some data and at some parse point, I need to update some statuslabel. Surprisingly, statuslabel is threadsafe… I didn’t know…

Ok, but the statuslabel needs to include some combo text which appears to be not thread safe

statLabel1.Text = “Connected to ” & cmbPort.text & “, found and happy”

So I tried to make a function to “Read Safe” from any component.text but I failed…

Private Delegate Function ControlGetTextDelegate(ByRef cmp As Control) As String
Public Function ControlGetText(ByRef cmp As Control) As String

    Dim s As String = ""

    ' control invoked from another thread ?
    If cmp.InvokeRequired Then ' YES, so call through delegate

        Dim dlg As New ControlGetTextDelegate(AddressOf ControlGetText)
        cmp.BeginInvoke(dlg, {cmp})

    Else ' NO, so call normally
        s = cmp.Text
    End If

    Return s

End Function

Can someone give a little help?

Answer 1

I think your problem is that you’re not assinging anything to s when InvokeRequired = True.

You can assign the result to s (you’ll need to make that Invoke instead of BeginInvoke), but it might be better to invoke the event handler that you’re calling this from instead. You didn’t post that code, but it is basically the same idea — test that InvokeRequired on the form, then call BeginInvoke for the event handler itself.