VB - How do I test if optional arguments are supplied or not?

Question

How do I test if optional arguments are supplied or not? -- in VB6 / VBA

Function func (Optional ByRef arg As Variant = Nothing)

    If arg Is Nothing Then   <----- run-time error 424 "object required"
        MsgBox "NOT SENT"
    End If

End Function

Answer 1

If IsMissing(arg) Then ...

Answer 2

Use IsIssing:

If IsMissing(arg) Then
    MsgBox "NOT SENT"
End If

However, if I remember correctly, this doesn’t work when giving a default for the argument, and in any case it makes using the default argument rather redundant.

Answer 3

You can use the IsMissing() Function. But this one only works with the Variant datatype.