関数を作成する際、列挙型を作成しておくと呼び出し時にリストから引数を選択できるので便利

例）WINDOWSアプリを起動する関数ルーチン

'列挙型の宣言
Enum WinAppType
    PHOTOED = 0
    KODAKING = 1
    ACROBAT = 2
    WORD = 3
End Enum

'関数側
Public Sub WinAppExec(ByVal wuType As WinAppType, Optional wuStyle As VbAppWinStyle = vbMaximizedFocus, Optional args As String)

    Dim Application As String

    Select Case wuType
        Case WinAppType.PHOTOED
            Application = Environ("CommonProgramFiles") & _
            "\Microsoft Shared\PhotoED\PHOTOED.EXE"

        Case WinAppType.KODAKING
            Application = "c:\windows\KODAKIMG.EXE"

        Case WinAppType.ACROBAT
            Application = Environ("ProgramFiles") & _
            "\Adobe\Acrobat 7.0\Reader\AcroRd32.exe"

        Case WinAppType.WORD
            Application = Environ("ProgramFiles") & _
            "\Microsoft Office\Office\WINWORD.EXE"

    End Select

    If Not IsMissing(args) Then

        'エラーを防ぐためにargsのダブルクォーテーションを一旦削除
        args = Replace(args, """", "")

        Application = Application & " """ & args & """"

    End If

    Call Shell(Application, wuStyle)

End Sub