Is there a way to count elements in a VBA enum? - excel

Question

is there a proper way to count elements of an enum in VBA ?
At the moment, I leave an enum value such as KeepThisOneHere in the following example
Enum TestEnum
ValueA
ValueB
ValueC
KeepThisOneHere
End Enum
I use the last value to know the size... I don't like this solution, because I am not sure I have a guarantee the values will always be indexed the same way, and the code might be changed by a third party who might add values after this last special one, silently breaking the rest of the code.

Answer 1

Not sure on the etiquette here, so I'll post it and if advised, I'll come back and delete it. Chip Pearson posted this code on the Code Cage Forums (http://www.thecodecage.com/forumz/microsoft-excel-forum/170961-loop-enumeration-constants.html). I don't have the TypeLinInfo DLL on my machine, so I can't test it (I'm sure google will turn up places to download TLBINF32.dll). Nonetheless, here is his entire post to save someone else from registering for a forum:
You can do this ONLY IF you have the TypeLibInfo DLL installed on your
computer. In VBA, go to the Tools menu, choose References, and scroll
down to "TypeLib Info". If this item exists, check it. If it does not
exist, then quit reading because you can't do what you want to do. The
file name of the DLL you need is TLBINF32.dll.
The following code shows how to get the names and values in the
XLYesNoGuess enum:
Sub AAA()
Dim TLIApp As TLI.TLIApplication
Dim TLILibInfo As TLI.TypeLibInfo
Dim MemInfo As TLI.MemberInfo
Dim N As Long
Dim S As String
Dim ConstName As String
Set TLIApp = New TLI.TLIApplication
Set TLILibInfo = New TLI.TypeLibInfo
Set TLILibInfo = TLIApp.TypeLibInfoFromFile( _
ThisWorkbook.VBProject.References("EXCEL").FullPath)
ConstName = "XLYesNoGuess"
For Each MemInfo In _
TLILibInfo.Constants.NamedItem(ConstName).Members
S = MemInfo.Name
N = MemInfo.Value
Debug.Print S, CStr(N)
Next MemInfo
End Sub
Using this knowledge, you can create two useful functions. EnumNames
returns an array of strings containing the names of the values in an
enum:
Function EnumNames(EnumGroupName As String) As String()
Dim TLIApp As TLI.TLIApplication
Dim TLILibInfo As TLI.TypeLibInfo
Dim MemInfo As TLI.MemberInfo
Dim Arr() As String
Dim Ndx As Long
Set TLIApp = New TLI.TLIApplication
Set TLILibInfo = New TLI.TypeLibInfo
Set TLILibInfo = TLIApp.TypeLibInfoFromFile( _
ThisWorkbook.VBProject.References("EXCEL").FullPath)
On Error Resume Next
With TLILibInfo.Constants.NamedItem(EnumGroupName)
ReDim Arr(1 To .Members.Count)
For Each MemInfo In .Members
Ndx = Ndx + 1
Arr(Ndx) = MemInfo.Name
Next MemInfo
End With
EnumNames = Arr
End Function
You would call this function with code such as:
Sub ZZZ()
Dim Arr() As String
Dim N As Long
Arr = EnumNames("XLYesNoGuess")
For N = LBound(Arr) To UBound(Arr)
Debug.Print Arr(N)
Next N
End Sub
You can also create a function to test if a value is defined for an
enum:
Function IsValidValue(EnumGroupName As String, Value As Long) As
Boolean
Dim TLIApp As TLI.TLIApplication
Dim TLILibInfo As TLI.TypeLibInfo
Dim MemInfo As TLI.MemberInfo
Dim Ndx As Long
Set TLIApp = New TLI.TLIApplication
Set TLILibInfo = New TLI.TypeLibInfo
Set TLILibInfo = TLIApp.TypeLibInfoFromFile( _
ThisWorkbook.VBProject.References("EXCEL").FullPath)
On Error Resume Next
With TLILibInfo.Constants.NamedItem(EnumGroupName)
For Ndx = 1 To .Members.Count
If .Members(Ndx).Value = Value Then
IsValidValue = True
Exit Function
End If
Next Ndx
End With
IsValidValue = False
End Function
This function returns True if Value is defined for EnumGroupName or
False if it is not defined. You would call this function with code
like the following:
Sub ABC()
Dim B As Boolean
B = IsValidValue("XLYesNoGuess", xlYes)
Debug.Print B ' True for xlYes
B = IsValidValue("XLYesNoGuess", 12345)
Debug.Print B ' False for 12345
End Sub
Cordially,
Chip Pearson
Microsoft MVP 1998 - 2010
Pearson Software Consulting, LLC
www.cpearson.com
[email on web site]

Answer 2

Here's an example of my workaround, which is pretty straightforward:
Enum FileSpecFields
FileSpecFields_Start '(zero-based)
FileNameIdx = FileSpecFields_Start
FolderNameIdx
BasePathIdx
FullPathIdx
CopyStatus
FileSpecFields_End = CopyStatus
End Enum
'...
ReDim FileSpecList(1 To MaxFiles, FileSpecFields_Start To FileSpecFields_End) As String
'...
But note that, if you are using a one-based Enum you may have to adjust the _End value definition, depending on how you're using it. Also, for zero-based Enums, the _End value is not the same as its count of items. And, if you add items at the end, you must update the _End value's definition accordingly. Finally, if your enum is a non-contiguous range of values, all bets are off with this approach!

Answer 3

there isn't a way to get the count.
What you have to do is loop through the elements of the Enum until you get to the last one.
Chip Pearson has some good tips on Enumerated constants: Chip Pearson: Enum Variable Type

Answer 4

If you know the enum type(s) on design-time you could transform them into a Static Property Get MyEnumColl() as Collection ... (no class needed, initialized on 1st access statically) and thus easily loop through them or count them like shown here

Answer 5

Sub count()
Dim n, c
For n = headers.frstItem To headers.lastItem
c = c + 1
Next
Debug.Print c
End Sub