GetHiddenClasses - Retrieve all the hidden classes in a type library

' Return a collection with all hidden types of a type library
'
' VB's Object Browser hides some types in a type library:
' you can show these types by right clicking on the Object Browser and
' activating the "Show hidden members" option. This option, however,
' shows only types labelled as "hidden", but still hides those whose name
' begins with the underscore character (_).

' Be sure that "TypeLib Information" type library (TlbInf32.tlb)
' is referenced in your VB project.

Function GetHiddenClasses(ByVal TypeLibFile As String) As Collection
    Dim TLI As New TLIApplication
    Dim TypeLibrary As TypeLibInfo
    Dim TypeInfo As TypeInfo
    Dim FileName As String
    
    ' raises an error if unable to open the type library
    ' (e.g. file not found or not a TLB)
    Set TypeLibrary = TLI.TypeLibInfoFromFile(TypeLibFile)
    
    ' prepare the result
    Set GetHiddenClasses = New Collection
    
    ' fill the return collection with hidden type names
    For Each TypeInfo In TypeLibrary.TypeInfos
        ' if the type is hidden, add to the result collection
        If TypeInfo.AttributeMask And TYPEFLAG_FHIDDEN Then
            GetHiddenClasses.Add TypeInfo.Name
        End If
    Next

End Function