Microsoft Office 2000/Visual Basic Programmer's Guide

Creating Methods

A method performs an action on or with an object. Any public Sub or Function procedure that you add to a class module becomes a method of the object. If a method is a Sub procedure, it doesn't return a value; if it is a Function procedure, it returns a value.

For example, the following procedure is the Multiply method for a hypothetical object named Calculator:

Public Function Multiply(ParamArray avarOperands() As Variant) As Variant
   ' Multiplies the set of numbers passed in to the procedure.
   Dim lngCount      As Long
   Dim dblResult   As Double
   Dim varElement   As Variant
   
   ' Initialize result to 1, since multiplying by 0 would
   ' return 0.
   dblResult = 1
   ' Loop through parameter array, from lower bound to upper
   ' bound.
   For lngCount = LBound(avarOperands) To UBound(avarOperands)
      ' Store value of element.
      varElement = avarOperands(lngCount)
      ' Check whether element is numeric.
      If IsNumeric(varElement) Then
         ' Multiply result by element.
         dblResult = dblResult * varElement
      Else
         ' Return Null if any element is not numeric.
         Multiply = Null
         GoTo Multiply_End
      End If
   Next

   Multiply = dblResult
   
Multiply_End:
   Exit Function
End Function

To call this method, create a new object of type Calculator, and pass in the values that you want to multiply, as shown in the following code fragment:

Dim calCalc As New Calculator
   
Debug.Print calCalc.Multiply(2.5, 2.5, 2.5)