Question

Is there a way to set a variable in VB.NET in an IF statement. I would like to do the following:

If (TypeOf sender Is TabControl And TypeOf e.Control Is TabPage) Then   'tab control is adding a tab page
    AddControl(CType(e.Control, TabPage))
ElseIf (TypeOf sender Is TabPage) Then                                  'tab page is adding some control
    AddControl(CType(sender, TabPage), e.Control)
ElseIf (tabPageFound = FindTabPageOf(sender)) IsNot Nothing Then
    tabPageFound.SomeAction()
End if

Is there some way I can get the last “ElseIf” to work? I know I can re-write it to get it to work but is there some syntax that will make it work the way it is?

Answer 1

I don’t use VB.NET (so mind the syntax errors). However, note that each “else if” can be trivially rewritten as an “else” with a nested “if”. Many languages, such as those based on the C-syntax, do not have a compound “else if” statement but have nicer support for “hanging if” statements.

In this case it might be rewritten as:

If (TypeOf sender Is TabControl And TypeOf e.Control Is TabPage) Then
    ...
ElseIf (TypeOf sender Is TabPage) Then
    ...
Else
    tabPageFound = FindTabPageOf(sender)
    If (tabPageFound) IsNot Nothing Then
        ...
    End
End If

Just something to consider.

---

For the sake of completeness this shows removal of all ElseIf usage and the resulting nesting:

If (TypeOf sender Is TabControl And TypeOf e.Control Is TabPage) Then
    ...
Else
    If (TypeOf sender Is TabPage) Then
        ...
    Else
        tabPageFound = FindTabPageOf(sender)
        If (tabPageFound) IsNot Nothing Then
            ...
        End If
    End If
End If