VBA - Auto check/uncheck microsoft script run time - vba

Question

I had the following function that auto add Microsoft Script Runtime Reference to the Reference list. However, if the user already had included Microsoft script runtime, it will show error Name conflicts with existing module,project, object library.
How do I set an condition that auto adds Microsoft script runtime if it is not included in the reference and do nothing if it has already being added?
Private Function AddScriptingLibrary() As Boolean
Const GUID As String = "{420B2830-E718-11CF-893D-00A0C9054228}"
On Error GoTo errHandler
ThisWorkbook.VBProject.References.AddFromGuid GUID, 1, 0
AddScriptingLibrary = True
Exit Function
errHandler:
MsgBox Err.Description
End Function

Answer 1

You'll need to enumerate the references of the project first, in order to check if the reference is already present.
I've added a reference to Microsoft Visual Basic for Applications Extensibility 5.3
Option Explicit
Function AddScriptingLibrary()
Const GUID_Scripting = "{420B2830-E718-11CF-893D-00A0C9054228}"
Dim proj As VBIDE.VBProject
Dim ref As VBIDE.Reference
Dim ScriptingLibraryIsReferenced As Boolean
Set proj = ThisWorkbook.VBProject
For Each ref In proj.References
If ref.GUID = GUID_Scripting Then
ScriptingLibraryIsReferenced = True
AddScriptingLibrary = True
Exit Function
End If
Next ref
If Not ScriptingLibraryIsReferenced Then
On Error GoTo errHandler
proj.References.AddFromGuid GUID_Scripting, 1, 0
AddScriptingLibrary = True
Exit Function
errHandler:
MsgBox Err.Description
End If
End Function
EDIT this does the same, but without the early-bound reference to Visual Basic For Applications Extensibility 5.3 reference:
Option Explicit
Function AddScriptingLibrary()
Const GUID_Scripting = "{420B2830-E718-11CF-893D-00A0C9054228}"
Dim proj As Object 'VBIDE.VBProject
Dim ref As Object 'VBIDE.Reference
Dim ScriptingLibraryIsReferenced As Boolean
Set proj = ThisWorkbook.VBProject
For Each ref In proj.References
If ref.GUID = GUID_Scripting Then
ScriptingLibraryIsReferenced = True
AddScriptingLibrary = True
Exit Function
End If
Next ref
If Not ScriptingLibraryIsReferenced Then
On Error GoTo errHandler
proj.References.AddFromGuid GUID_Scripting, 1, 0
AddScriptingLibrary = True
Exit Function
errHandler:
MsgBox Err.Description
End If
End Function
But then, if you're happy with the down-sides of late-bound code, you don't even need the reference to Scripting.Runtime, because you can just use:
Option Explicit
Sub PrintDriveCount()
Dim FSO As Object
Set FSO = CreateObject("Scripting.FileSystemObject")
'Print the number of drives in the FileSystemObject
Debug.Print FSO.Drives.Count
End Function