Missing reference vs unchecked reference runtime

[Kyle123]

I am in the unenviable position of coming up with a workbook that does a load of VBA for people with computers that I do not know the spec of. I know the below works when I remove the reference to MSXML, however am I likely to run into any issues should the relevant MSXML library be missing rather than me unselecting whilst testing? I don't know whether missing behaves differently to an unchecked reference.

    Dim request As IWebRequest
    Dim parser As IDataParser

    Set request = New DataRequest

    request.Url = CONSTANTS.Url
    request.Authenticator = CONSTANTS.AUTH_STRING
    request.Timeout = 12
    request.CallType = Legacy
    
    If LateBind Then
        Set parser = New LegacyDataParser
    Else
        Set parser = New DataParser
    End If
    
    Set parser.WebRequest = request

IDataParser

Public Property Set WebRequest(ByVal RHS As IWebRequest): End Property
Public Property Get WebRequest() As IWebRequest: End Property

Public Function GetData() As Variant: End Function

DataParser

Option Explicit
Implements IDataParser

Private m_IWebRequest As IWebRequest

Private Function IDataParser_GetData() As Variant

    Dim doc As Object
    Set doc = New MSXML2.DOMDocument60

    doc.LoadXML m_IWebRequest.GetData
    IDataParser_GetData = ParseData(doc)
    
End Function
'...

LegacyDataParser

Option Explicit
Implements IDataParser

Private m_IWebRequest As IWebRequest

Private Function IDataParser_GetData() As Variant

    Dim doc As Object
    Set doc = CreateObject("MSXML2.DOMDocument")

    doc.LoadXML m_IWebRequest.GetData
    IDataParser_GetData = ParseData(doc)
    
End Function

I've previously posted this at EF here, but had no response: https://www.excelforum.com/excel-pr...reference-vs-unchecked-reference-runtime.html

 

[Jaafar Tribak]

Have you considered using CallByName on an object of the library and wrap it in a Boolean function? If the lib us not available (missing or unselected) it should raise a runtime error which can be handled and thus allowing code to decide between early and latebind.

 

[Jaafar Tribak]

No... I take back what I said.

The CallbyName Method would only be useful for determining the version of the library not if it is misiing.

Sorry.

 

[Kyle123]

Thanks Jaafar, in this case I reckon checking for the presence of msxml6.dll should be enough to check whether the reference would be missing. I hadn’t thought of automating it, much appreciated!