An alternative way of handling versioning of an XLA file is to use a custom property in Document Properties. You can access and manipulate using COM as described here: http://support.microsoft.com/?kbid=224351.
Advantages of this are:
Another alternative would be to store the version number (possibly other configuration data too) on a worksheet in the XLA file. The worksheet would not be visible to users of the XLA. One technique I have used in the past is to store the add-in as an XLS file in source control, then as part of the build process (e.g. in a Post-Build event) run the script below to convert it to an XLA in the output directory. This script could be easily extended to update a version number in a worksheet before saving. In my case I did this because my Excel Add-in used VSTO, and Visual Studio doesn't support XLA files directly.
'
' ConvertToXla.vbs
'
' VBScript to convert an Excel spreadsheet (.xls) into an Excel Add-In (.xla)
'
' The script takes two arguments:
'
' - the name of the input XLS file.
'
' - the name of the output XLA file.
'
Option Explicit
Dim nResult
On Error Resume Next
nResult = DoAction
If Err.Number <> 0 Then
Wscript.Echo Err.Description
Wscript.Quit 1
End If
Wscript.Quit nResult
Private Function DoAction()
Dim sInputFile, sOutputFile
Dim argNum, argCount: argCount = Wscript.Arguments.Count
If argCount < 2 Then
Err.Raise 1, "ConvertToXla.vbs", "Missing argument"
End If
sInputFile = WScript.Arguments(0)
sOutputFile = WScript.Arguments(1)
Dim xlApplication
Set xlApplication = WScript.CreateObject("Excel.Application")
On Error Resume Next
ConvertFileToXla xlApplication, sInputFile, sOutputFile
If Err.Number <> 0 Then
Dim nErrNumber
Dim sErrSource
Dim sErrDescription
nErrNumber = Err.Number
sErrSource = Err.Source
sErrDescription = Err.Description
xlApplication.Quit
Err.Raise nErrNumber, sErrSource, sErrDescription
Else
xlApplication.Quit
End If
End Function
Public Sub ConvertFileToXla(xlApplication, sInputFile, sOutputFile)
Dim xlAddIn
xlAddIn = 18 ' XlFileFormat.xlAddIn
Dim w
Set w = xlApplication.Workbooks.Open(sInputFile,,,,,,,,,True)
w.IsAddIn = True
w.SaveAs sOutputFile, xlAddIn
w.Close False
End Sub