How can I reduce this code to a single procedure - vb.net

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

Answer 2

You can leverage a couple of features:
1) The VB Handles statement can hook multiple control events to the same method.
2) You can get the combobox from the sender, then extract the index.
3) From the index, you can find the other associated controls.
Private Sub cboCalc_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboCalc0.SelectedIndexChanged, cboCalc1.SelectedIndexChanged, cboCalc2.SelectedIndexChanged, cboCalc3.SelectedIndexChanged
Dim oCombo As ComboBox
oCombo = DirectCast(sender, ComboBox)
Dim wIndex As Integer
Dim oTree As TreeView
Dim oTextBox As TextBox
wIndex = CInt(oCombo.Name.Substring(oCombo.Name.Length - 1))
oTree = DirectCast(Me.Controls.Find("trvSignals" & wIndex.ToString, True)(0), TreeView)
oTextBox = DirectCast(Me.Controls.Find("txtSignalName" & wIndex.ToString, True)(0), TextBox)
If oTree.SelectedNode IsNot Nothing AndAlso oTextBox.Enabled AndAlso oTree.SelectedNode.Level = 3 Then
tempChannelProp(wIndex, oTree.SelectedNode.Tag).CalcVariant = oCombo.SelectedIndex
End If
End Sub

Answer 3

There is likely a more elegant solution to your problem somewhere. I find that, if I am defining the same controls and methods for multiplpe tabs on a tab control, it might be time to examine my design . . . Not always, though. :-)
This might be a little less clumsy, although using Select Case to choose between otherwise identical configurations of UI elements gives me the heebie-jeebies (It DOES get all your code into one handler, however):
Private Sub PerformCalcs(ByVal sender As Object, ByVal e As System.EventArgs) _
Handles _
cboCalc0.SelectedIndexChanged,
cboCalc1.SelectedIndexChanged,
cboCalc2.SelectedIndexChanged,
cboCalc3.SelectedIndexChanged
Dim cboCalc As ComboBox = DirectCast(sender, ComboBox)
' The Parent of the combo box is the TabPage, and the Parent of the TabPage is the TabControl:
Dim t As TabControl = cboCalc.Parent.Parent
Dim SelectedNode As TreeNode
Dim TxtSignalName As TextBox
' The TabControl knows the index value of the currently selected tab:
Select Case t.SelectedIndex
Case 0 'Page 0
SelectedNode = trvSignals0.SelectedNode
TxtSignalName = txtSignalName0
Case 1 ' Page 1
SelectedNode = trvSignals1.SelectedNode
TxtSignalName = txtSignalName1
Case 2 ' Page 2
SelectedNode = trvSignals2.SelectedNode
TxtSignalName = txtSignalName2
Case 3 ' Page 3
SelectedNode = trvSignals3.SelectedNode
TxtSignalName = txtSignalName3
Case Else ' Ooops! Something horrible happened!
Throw New System.Exception("You have passed an invalid Control as a parameter")
End Select
If (Not (IsNothing(SelectedNode)) And TxtSignalName.Enabled = True) AndAlso trvSignals3.SelectedNode.Level = 3 Then
tempChannelProp(3, SelectedNode.Tag).CalcVariant = cboCalc.SelectedIndex
End If
End Sub