Why do vba worksheet modules export as .cls modules?

perkin_warbeck 

Attribute VB_Name = "Mod_Vba"
' DESCRIPTION
'   This module can export and inport module by Workbook_BeforeSave event. Thus the files can be managed by version
'   control tools or edited in other IDE then imported back.
' USAGE
'   1. Import this module to a workbook.
'   2. In the Workbook_BeforeSave event, add: Syn "FULL_PATH_TO_YOUR_MODULE_FILE", "MODULE_NAME". eg.
'        Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
'            Syn "C:\projects\vba_lib\Mod_Vba.bas", "Mod_Vba"
'            Syn "C:\projects\vba_lib\Mod_Debug.bas"    ' If omit the module name, the module will be named as the file
'        End Sub
'   3. Save the workbook. The module will be imported.
'   4. Change the file in some 3rd-party editor and save. Save the workbook, the module will be imported.
'   5. Change the module code in VBA Editor. Save the workbook, the module will be exported.
' NOTE
'   * Path string in this module must be ended with "\"
'   * Path provided to Syn() must be absolute path
'   * This module should be named as 'Mod_Vba', otherwise need to change predefined name in ImportModule() accordingly

Option Explicit
Option Base 1

Public Function Syn(ByVal sFile As String, Optional ByVal sModule As String)
    Dim bModule As Boolean, bFile As Boolean

    ' Check if file exists
    bFile = (Dir(sFile) <> "")

    ' Use file name as module name if not specified
    If sModule = "" Then
        sModule = Mid(sFile, InStrRev(sFile, "\") + 1)          ' Get file name
        sModule = Left(sModule, InStrRev(sModule, ".") - 1)   ' Remove extension
    End If

    ' Check if module exists
    bModule = InCollection(sModule, ActiveWorkbook.VBProject.VBComponents)

    If bFile = True And bModule = False Then
        ' Import the file if no module
        ImportModule sFile, sModule
    ElseIf bFile = False And bModule = True Then
        ' Export the module if no file
        ExportModule sModule, sFile
    ElseIf bFile = True And bModule = True Then
        Dim nDateDiff As Double
        nDateDiff = CDbl(Format(FileDateTime(sFile), "YYYYMMDDHHMMSS"))
        nDateDiff = nDateDiff - CDbl(GetModuleStamp(sModule))
        If nDateDiff > 0 Then
            ' Import the file if it is newer.
            ' NOTE: Any modification of module in VBE will be overwritten.
            ImportModule sFile, sModule
        ElseIf ActiveWorkbook.VBProject.VBComponents(sModule).Saved = False _
            Or nDateDiff < 0 Then
            ' Export if module is modified while file remains.
            ExportModule sModule, sFile
        Else
            Debug.Print "Synchronised " & sFile & " with " & sModule
            Exit Function
        End If
    Else
        Err.Raise 1, "Mod_Vba\Syn", "Neither file nor module are found."
        Exit Function
    End If

    Syn = SetModuleStamp(sModule, sFile)
    Debug.Print "Synchronised " & sFile & " with " & sModule

End Function

Public Function InCollection(Item As Variant, Parent As Variant) As Boolean
    On Error Resume Next
    Parent.Item Item
    InCollection = (Err.Number = 0)
    On Error GoTo 0
End Function

Private Function GetModuleStamp(ByVal sModule As String) As String
    If Not InCollection(sModule, ActiveWorkbook.VBProject.VBComponents) Then Exit Function

    GetModuleStamp = ActiveWorkbook.VBProject.Description

    Dim nPos As Long
    nPos = InStr(1, GetModuleStamp, sModule)
    If nPos > 0 Then GetModuleStamp = Mid(GetModuleStamp, nPos + Len(sModule) + 1, 14) Else GetModuleStamp = "0"

    Debug.Print sModule & " stamp: " & GetModuleStamp
End Function

Private Function SetModuleStamp(ByVal sModule As String, ByVal TimeStamp) As String
    If Not InCollection(sModule, ActiveWorkbook.VBProject.VBComponents) Then Exit Function

    Dim sTimeStamp As String

    ' If TimeStamp is a file String then get the FileDateTime, else it is provided as a Date
    If TypeName(TimeStamp) = "String" Then TimeStamp = FileDateTime(TimeStamp)

    TimeStamp = Format(TimeStamp, "YYYYMMDDHHMMSS")

    ' Store module timestamp in VBProject.Desciption
    ' Format: ModuleName@YYYYMMDDHHMMSS,ModuleName@YYYYMMDDHHMMSS
    Dim nPos As Long

    SetModuleStamp = ActiveWorkbook.VBProject.Description

    ' Find the module position in timestamp string
    nPos = InStr(1, SetModuleStamp, sModule)
    If nPos > 0 Then
        ' If module found, update the timestamp
        SetModuleStamp = Left(SetModuleStamp, nPos - 1) & sModule & "@" & TimeStamp & "," & Mid(SetModuleStamp, nPos + Len(sModule) + 16)
    Else
        'Module not found, append the new timestamp
        SetModuleStamp = SetModuleStamp & sModule & "@" & TimeStamp & ","
    End If
    ActiveWorkbook.VBProject.Description = SetModuleStamp

    Debug.Print "Module stamp updated: " & SetModuleStamp
End Function

Public Function ImportModule(ByVal sFile As String, Optional ByVal sModule As String, Optional ByVal sWorkbookName As String = "") As String
    Dim wbSource As Excel.Workbook
    Dim oVBC

    ' Use ActiveWorkbook by default
    If sWorkbookName = "" Then sWorkbookName = ActiveWorkbook.Name
    Set wbSource = Application.Workbooks(sWorkbookName)

    Set oVBC = ActiveWorkbook.VBProject.VBComponents

    ' Use file name as module name if not specified
    If sModule = "" Then
        sModule = Mid(sFile, InStrRev(sFile, "\") + 1)          ' Get file name
        sModule = Left(sModule, InStrRev(sModule, ".") - 1)   ' Remove extension
    End If

    ' Check if module exists
    If InCollection(sModule, oVBC) Then
        ' If module exists, rename old module
        oVBC(sModule).Name = sModule & "__Old__"

        ' Import the new module and rename
        oVBC.import sFile
        oVBC(oVBC.Count).Name = sModule

        ' For this module, the timestamp needs to be set before removing.
        If sModule = "Mod_Vba" Then SetModuleStamp sModule, sFile

        ' Delete the old module
        oVBC.Remove oVBC(sModule & "__Old__")
    Else
        ' If module does not exist, import and rename
        oVBC.import sFile
        oVBC(oVBC.Count).Name = sModule
    End If
    ImportModule = sModule

    Debug.Print sModule & " imported from " & sFile
End Function

Public Function ExportModule(Optional ByVal sModule As String = "", Optional ByVal sPath As String = "", Optional ByVal sWorkbookName As String = "")
    Dim sFile As String, sExt As String
    Dim wbSource As Excel.Workbook
    Dim oVBC

    ' Use ActiveWorkbook by default
    If sWorkbookName = "" Then sWorkbookName = ActiveWorkbook.Name
    Set wbSource = Application.Workbooks(sWorkbookName)

    If wbSource.VBProject.Protection = 1 Then
        Debug.Print "Error: The VBA in this workbook is protected, not possible to export the code."
        Exit Function
    End If

    ' Use workbook folder by default
    If sPath = "" Then sPath = wbSource.path & "\"

    If sModule = "" Then
        ' Export all modules if not specified
        For Each oVBC In wbSource.VBProject.VBComponents
            ' Match file extension with module type
            sExt = ModuleTypeExt(oVBC.Type)
            sFile = sPath & oVBC.Name & sExt
            If sExt <> "" Then oVBC.Export sFile
            Debug.Print sModule & " exported to " & sFile
        Next
    ElseIf InCollection(sModule, wbSource.VBProject.VBComponents) Then
        ' Export specific module
        Set oVBC = wbSource.VBProject.VBComponents(sModule)
        If Right(sPath, 1) = "\" Then
            ' If only path is given, use module name as file name
            sExt = ModuleTypeExt(oVBC.Type)
            sFile = sPath & oVBC.Name & sExt
        Else
            ' If full path is given
            sFile = sPath
        End If
        oVBC.Export sFile
        Debug.Print sModule & " exported to " & sFile
    End If
End Function

Private Function ModuleTypeExt(ByVal nModuleType) As String
    ' Check VBComponent.Type
    Select Case nModuleType
        Case 1
            ModuleTypeExt = ".bas"
        Case 2
            ModuleTypeExt = ".cls"
        Case 3
            ModuleTypeExt = ".frm"
        Case Else
            ' Worksheet or workbook object.
            ModuleTypeExt = ""
    End Select
End Function

I am not sure it is bug or not.

I used to run above VBA to export and import codes.

Hope helpful.