Private Enum OperatorEnum
    PLUS = 0
    MINUS
    MUL
    DIV
    POT
    AND_
    OR_
    NOT_
End Enum
 
Private Function WendeOperatorAn(Operator As OperatorEnum, Operand1 As Variant, _
  Operand2 As Variant) As Variant
    Dim RueckgabeWert As Variant
    Select Case Operator
    Case PLUS
        RueckgabeWert = Operand1 + Operand2
    Case MINUS
        RueckgabeWert = Operand1 - Operand2
    Case MUL
        RueckgabeWert = Operand1 * Operand2
    Case DIV
        RueckgabeWert = Operand1 / Operand2
    Case POT
        RueckgabeWert = Operand1 ^ Operand2
    Case AND_
        RueckgabeWert = Operand1 And Operand2
    Case OR_
        RueckgabeWert = Operand1 Or Operand2
    Case NOT_
        RueckgabeWert = Not Operand1
    End Select
    WendeOperatorAn = RueckgabeWert
End Function

MsgBox WendeOperatorAn(PLUS, 3, 4)

Dim TestOperator1 as OperatorEnum, TestOperator2 as OperatorEnum
TestOperator1 = MINUS
MsgBox WendeOperatorAn(TestOperator1, 10, 6)
 
TestOperator2 = 1
MsgBox WendeOperatorAn(TestOperator2, 10, 6)