How to add a reference programmatically

Question

I\'ve written a program that runs and messages Skype with information when if finishes. I need to add a reference for Skype4COM.dll in order to

Answer 1

Browsing the registry for guids or using paths, which method is best. If browsing the registry is no longer necessary, won't it be the better way to use guids? Office is not always installed in the same directory. The installation path can be manually altered. Also the version number is a part of the path. I could have never predicted that Microsoft would ever add '(x86)' to 'Program Files' before the introduction of 64 bits processors. If possible I would try to avoid using a path.

The code below is derived from Siddharth Rout's answer, with an additional function to list all the references that are used in the active workbook. What if I open my workbook in a later version of Excel? Will the workbook still work without adapting the VBA code? I have already checked that the guids for office 2003 and 2010 are identical. Let's hope that Microsoft doesn't change guids in future versions.

The arguments 0,0 (from .AddFromGuid) should use the latest version of a reference (which I have not been able to test).

What are your thoughts? Of course we cannot predict the future but what can we do to make our code version proof?

Sub AddReferences(wbk As Workbook)
    ' Run DebugPrintExistingRefs in the immediate pane, to show guids of existing references
    AddRef wbk, "{00025E01-0000-0000-C000-000000000046}", "DAO"
    AddRef wbk, "{00020905-0000-0000-C000-000000000046}", "Word"
    AddRef wbk, "{91493440-5A91-11CF-8700-00AA0060263B}", "PowerPoint"
End Sub

Sub AddRef(wbk As Workbook, sGuid As String, sRefName As String)
    Dim i As Integer
    On Error GoTo EH
    With wbk.VBProject.References
        For i = 1 To .Count
            If .Item(i).Name = sRefName Then
               Exit For
            End If
        Next i
        If i > .Count Then
           .AddFromGuid sGuid, 0, 0 ' 0,0 should pick the latest version installed on the computer
        End If
    End With
EX: Exit Sub
EH: MsgBox "Error in 'AddRef'" & vbCrLf & vbCrLf & err.Description
    Resume EX
    Resume ' debug code
End Sub

Public Sub DebugPrintExistingRefs()
    Dim i As Integer
    With Application.ThisWorkbook.VBProject.References
        For i = 1 To .Count
            Debug.Print "    AddRef wbk, """ & .Item(i).GUID & """, """ & .Item(i).Name & """"
        Next i
    End With
End Sub

The code above does not need the reference to the "Microsoft Visual Basic for Applications Extensibility" object anymore.