Imports System.IO
Public Class clsLog
    Private strMessage As String
    Private strPath As String
    Private bolOverwriteLogfile As Boolean
 
    Public Sub New(Optional ByVal Path As String = "log.txt", Optional ByVal _
      OverwriteLogfile As Boolean = True)
 
        Me.Path = Path
        Me.OverwriteLogfile = OverwriteLogfile
 
    End Sub
 
    Public Sub Log(ByVal Message As String)
 
        Dim objStreamWriter As StreamWriter
 
        objStreamWriter = New StreamWriter(Me.Path, Me.OverwriteLogfile)
        If Me.OverwriteLogfile = True Then Me.OverwriteLogfile = False
 
        Debug.WriteLine(Message)
        objStreamWriter.WriteLine(Message)
 
        objStreamWriter.Close()
 
    End Sub
 
    Public Property Message() As String
        Get
            Return strMessage
        End Get
 
        Set(ByVal value As String)
            strMessage = value
            Log(Message)
        End Set
 
    End Property
 
    Public Property Path() As String
        Get
            Return strPath
        End Get
 
        Set(ByVal value As String)
            strPath = value
        End Set
 
    End Property
 
    Public Property OverwriteLogfile() As Boolean
        Get
            Return bolOverwriteLogfile
        End Get
 
        Set(ByVal value As Boolean)
            bolOverwriteLogfile = value
        End Set
 
    End Property
End Class

 
Public Class frmMain
    Dim objLog As New clsLog()
 
    Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
 
        objLog.Message = "Main Form Load"
 
    End Sub
 
End Class

 
Public Class frmMain
    Dim objLog As New clsLog()
 
    Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
 
        objLog.Message = "Main Form Load"
 
        Dim arrSubFolders As New ArrayList        
        clsFolder.GetSubFolders(Path, arrSubFolders, objLog.Message)
 
    End Sub
 
End Class

 
Public Class clsFolder
 
    Public Shared Sub GetSubFolders(ByVal Path As String, ByRef SubFolders As _
      ArrayList, ByRef Logmessage As String)
        Logmessage = "Diese Nachricht erscheint nicht im Log"
        Logmessage = "Aber die letzte Nachricht (letzter Wert der Variable)" & _
          "erscheint im Log"
 
    End Sub
End Class