Detect included libraries in ASP

My ASP applications rely a lot on included libraries. As I usually end up with a complex hierarchy of libraries, it's not always possible to include the required modules in the dependent library. This makes debugging a bit more interesting, as you cannot be sure all the prerequisites have been included in the main .asp page unless you test all code paths.

To work around this problem, I wrote a small routine that checks for existence of prerequisite functions and throws an exception documenting what went wrong.

'
' CheckIncludedLibrary - checks if the incRoutine is available, 
'   otherwise throws an exception documenting that srcLibrary 
'   needs incLibrary
'
Sub CheckIncludedLibrary(incRoutine,srcLibrary,incLibrary)
  Dim routineRef
  
  On Error Resume Next
  Set routineRef = GetRef(incRoutine)
  If Err.Number <> 0 Then On Error Goto 0 : _
    Err.Raise vbObjectError+1,srcLibrary, _
    "You have to include " & incLibrary
End Sub

You would use this routine in a way similar to the example below:

'
' This library requires inclusion of /forms/xmlLibrary.asp, 
' /forms/lib/editLibrary.asp and /asp/incPostingPreview.asp
'

CheckIncludedLibrary "NewXMLTextElement", _
  "listRoutesLibrary","/forms/xmlLibrary"
CheckIncludedLibrary "EnrichElementText", _
  "listRoutesLibrary","/forms/lib/editLibrary"
CheckIncludedLibrary "PostToPreview", _
  "listRoutesLibrary","/asp/incPostingPreview"