How can I use enum identifiers in Excel UDF - enums

Question

I've created a function called EnergyPrice with the following code:
Here's the pricetable I'm looking up from
Prijstabel
fixed variable
Startdate Einddate gas electra gas electra
€/a €/a ct/KWh ct/KWh
1-1-2010 1-7-2010 181,00 235,00 0,11 0,33
1-7-2010 1-1-2011 362,00 470,00 0,33 1,30
1-1-2011 1-7-2011 191,00 245,00 0,22 0,65
1-7-2011 1-1-2012 162,35 208,25 0,19 0,55
1-1-2012 1-7-2012 324,70 416,50 0,37 1,11
And here's the relevant code
Public Enum Energietype
v_gas = 1
v_electricity = 2
End Enum
Public Enum FixedOrVariable
v_fixed = 1
v_variable = 2
End Enum
Public Function EnergyPrice(PriceDate As Date, E_type As Energietype, variabel As FixedOrVariable) As Variant
Dim PrijsTable As Range
Dim RowNr As Integer
Dim Found As Boolean
Dim KolomNr As Integer
Set PrijsTable = Range("EnergyPriceTable")
If PrijsTable.Columns.Count <> 6 Then Err.Raise Number:=vbObjectError + 1000, Description:="No valid valid pricetable defined"
RowNr = 1
Found = False
While Not (Found) And (RowNr <= PriceTable.Rows.Count)
Found = (PriceTable.Cells(RowNr, 1).Value <= PriceDate) And (PriceTable.Cells(RowNr, 2) > PriceDate)
If Not (Found) Then RowNr = RowNr + 1
Wend
If Found Then
If E_type = v_gas Then KolomNr = 1
If E_type = v_elektra Then KolomNr = 2
If variabel = v_variabel Then KolomNr = KolomNr * 2
KolomNr = KolomNr + 2
EnergyPrice = PriceTable.Cells(RowNr, KolomNr).Value
Else
EnergyPrice = Empty
End If
End Function
The question is how do I use the above enums in an Excel spreadsheet? So I can enter a formula like:
If I use the numbers 1,2 the functions works fine, but I want to use the enum names.
Can this be done using only Excel VBA?

Answer 1

If you add the enums to the workbook as defined names, you can pass them into functions and the value that is passed is the actual value you set the enum for. Do this manually or via VBA if you prefer.
Example:
ActiveWorkbook.Names.Add Name:="v_gas", RefersToR1C1:="=1"
ActiveWorkbook.Names.Add Name:="v_fixed", RefersToR1C1:="=2"

Answer 2

The only way I see, is by defining Names in your workbook, assigning them the constants of your Enums.
From the menu: Insert ... Name .... Define
Name: v_gas
Refers to: =1
Alternatively, you could create those names by VBA, but that has no interest, since it will be a 1 shot (names are saved with the workbook).
By using such names, the users will be able to use F3 while entering the formula.