So the main goal of this function is to :

• Be standalone because it needs to be written in the main VbScript file and cannot be in an included file (because it defines the include function)
• Provide enough information if something goes wrong (ie. the file that was being included, the error that occurred, ...)
• Include a file once and only once to avoid include loops.

' *************************************************************************************************
'! Includes a VbScript file
'! @param p_Path    The path of the file to include
' *************************************************************************************************
Sub IncludeFile(p_Path)
    ' only loads the file once
    If std_internal_LibFiles.Exists(p_Path) Then
        Exit Sub
    End If
    
    ' registers the file as loaded to avoid to load it multiple times
    std_internal_LibFiles.Add p_Path, p_Path

    Dim objFso, objFile, strFileContent, strErrorMessage
    Set objFso = CreateObject("Scripting.FileSystemObject")
    
    ' opens the file for reading
    On Error Resume Next
    Set objFile = objFso.OpenTextFile(p_Path)
    If Err.Number <> 0 Then
        ' saves the error before reseting it
        strErrorMessage = Err.Description & " (" &  Err.Source & " " & Err.Number & ")"
        On Error Goto 0
        Err.Raise -1, "ERR_OpenFile", "Cannot read '" & p_Path & "' : " & strErrorMessage
    End If
    
    ' reads all the content of the file
    strFileContent = objFile.ReadAll
    If Err.Number <> 0 Then
        ' saves the error before reseting it
        strErrorMessage = Err.Description & " (" &  Err.Source & " " & Err.Number & ")"
        On Error Goto 0
        Err.Raise -1, "ERR_ReadFile", "Cannot read '" & p_Path & "' : " & strErrorMessage
    End If
    
    ' this allows to run vbscript contained in a string
    ExecuteGlobal strFileContent
    If Err.Number <> 0 Then
        ' saves the error before reseting it
        strErrorMessage = Err.Description & " (" &  Err.Source & " " & Err.Number & ")"
        On Error Goto 0
        Err.Raise -1, "ERR_Include", "An error occurred while including '" & p_Path & "' : " & vbCrlf & strErrorMessage
    End If
End Sub

To include a file in another file, just use the one liner :

IncludeFile "myOtherFile.vbs"

Before we use the IncludeFile method, we need to :

• Declare std_internal_LibFiles globally
• Initialize it with a new dictionary

Dim std_internal_LibFiles
Set std_internal_LibFiles = CreateObject("Scripting.Dictionary")