Question

I am relatively new to the whole .NET thing, coming from a VB classic background.

On my form I have a tabcontrol, with 4 tabs. Most of the code is handled using a shared handler, but for the others I have to write a handler for each.

How can I optimize these routines into a single procedure?

    Private Sub cboCalc0_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboCalc0.SelectedIndexChanged
    'Page 0
    If (Not (IsNothing(trvSignals0.SelectedNode)) And txtSignalName0.Enabled = True) AndAlso trvSignals0.SelectedNode.Level = 3 Then
        tempChannelProp(0, trvSignals0.SelectedNode.Tag).CalcVariant = cboCalc0.SelectedIndex
    End If
End Sub

Private Sub cboCalc1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboCalc1.SelectedIndexChanged
    'Page 1
    If (Not (IsNothing(trvSignals1.SelectedNode)) And txtSignalName0.Enabled = True) AndAlso trvSignals1.SelectedNode.Level = 3 Then
        tempChannelProp(1, trvSignals1.SelectedNode.Tag).CalcVariant = cboCalc1.SelectedIndex
    End If
End Sub

Private Sub cboCalc2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboCalc2.SelectedIndexChanged
    'Page 2
    If (Not (IsNothing(trvSignals2.SelectedNode)) And txtSignalName2.Enabled = True) AndAlso trvSignals2.SelectedNode.Level = 3 Then
        tempChannelProp(2, trvSignals2.SelectedNode.Tag).CalcVariant = cboCalc2.SelectedIndex
    End If
End Sub

Private Sub cboCalc3_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboCalc3.SelectedIndexChanged
    'Page 3
    If (Not (IsNothing(trvSignals3.SelectedNode)) And txtSignalName3.Enabled = True) AndAlso trvSignals3.SelectedNode.Level = 3 Then
        tempChannelProp(3, trvSignals3.SelectedNode.Tag).CalcVariant = cboCalc3.SelectedIndex
    End If
End Sub

I have handled the other bits as follows, and it works great, but I just cannot figure out how to do it with code like that above.

    Private Sub trvSignals_AfterCheck(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles trvSignals0.AfterCheck, trvSignals1.AfterCheck, trvSignals2.AfterCheck, trvSignals3.AfterCheck
    'Handles Page 0,1,2,3
    sender.SelectedNode = e.Node
    If e.Node.Level = 3 Then
        tempChannelProp(sender.tag, e.Node.Tag).Active = e.Node.Checked
    End If
End Sub

I use the tag property of the control of each page to hold either 0,1,2 or 3 as appropriate.

Thanks

Graham

Answer 1

Create control arrays that you can reference by index, and put the index in each controls’ Tag.

Class MyForm

    Private ReadOnly cboCalcArray As ComboBox()
    Private ReadOnly trvSignalsArray As TreeView()
    Private ReadOnly txtSignalNameArray As TextBox()

    Public Sub New()
        InitializeComponent()
        cboCalcArray = new ComboBox() {cboCalc0, cboCalc1, cboCalc2, cboCalc3}
        trvSignalsArray = new TreeView() {trvSignals0, trvSignals1, trvSignals2, trvSignals3}
        txtSignalNameArray = new TextBox() {txtSignalName0, txtSignalName1, txtSignalName2, txtSignalName3}
    End Sub

    Private Sub cboCalcX_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) _
        Handles cboCalc0.SelectedIndexChanged, 
                cboCalc1.SelectedIndexChanged, 
                cboCalc2.SelectedIndexChanged, 
                cboCalc3.SelectedIndexChanged
        Dim index As Integer = sender.Tag
        If (Not (IsNothing(trvSignalsArray(index).SelectedNode)) And txtSignalNameArray(index).Enabled = True) AndAlso trvSignals2.SelectedNode.Level = 3 Then      
            tempChannelProp(index, trvSignalsArray(index).SelectedNode.Tag).CalcVariant = cboCalcArray(index).SelectedIndex      
        End If      
    End Sub
End Class