VB - Rückgabewerte mit Pfiff

Namespace OkResult

    ''' <summary>
    ''' flexible Rückgabeparameter
    ''' mit einer evtl. Fehlermeldung
    ''' </summary>
    ''' <remarks></remarks>
    Interface IBoolMultiResult
        Property IsOk() As Boolean
        Property ErrMsg() As String
    End Interface

    ''' <summary>
    ''' flexible Rückgabeparameter
    ''' mit typgerechter Rückgabe und
    ''' mit einer evtl. Fehlermeldung
    ''' </summary>
    ''' <typeparam name="T"></typeparam>
    ''' <remarks></remarks>
    Interface IBoolObjectResult(Of T)
        Property IsOk() As Boolean
        Property Result() As T
        Property ErrMsg() As String
    End Interface

    Public Class BoolResult
        Implements IBoolMultiResult

        Private m_err As String = ""
        Private m_IsOK As Boolean

        Public Sub New()
        End Sub
        Public Sub New(ByVal bIsOk As Boolean, Optional ByVal sErrMsg As String = "")
            m_err = sErrMsg : m_IsOK = bIsOk
        End Sub

        ''' <summary>
        ''' Bei IsOK=false sollte hier eine Fehlermeldung stehen
        ''' </summary>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Public Property ErrMsg() As String Implements IBoolMultiResult.ErrMsg
            Get
                Return m_err
            End Get
            Set(ByVal value As String)
                m_err = value
            End Set
        End Property
        ''' <summary>
        ''' Ob die Aktion mit/ohne Fehler abgeschlossen wurde
        ''' </summary>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Public Property IsOk() As Boolean Implements IBoolMultiResult.IsOk
            Get
                Return m_IsOK
            End Get
            Set(ByVal value As Boolean)
                m_IsOK = value
            End Set
        End Property
    End Class

    Public Class ObjectResult(Of T)
        Implements IBoolObjectResult(Of T)

        Private m_err As String = ""
        Private m_IsOK As Boolean
        Private m_Result As T

        Public Sub New()
        End Sub
        Public Sub New(ByVal tResult As T, ByVal bIsOk As Boolean, Optional ByVal sErrMsg As String = "")
            m_err = sErrMsg : m_IsOK = bIsOk
            m_Result = tResult
        End Sub

        ''' <summary>
        ''' Bei IsOK=false sollte hier eine Fehlermeldung stehen
        ''' </summary>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Public Property ErrMsg() As String Implements IBoolObjectResult(Of T).ErrMsg
            Get
                Return m_err
            End Get
            Set(ByVal value As String)
                m_err = value
            End Set
        End Property
        ''' <summary>
        ''' Ob die Aktion mit/ohne Fehler abgeschlossen wurde
        ''' </summary>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Public Property IsOk() As Boolean Implements IBoolObjectResult(Of T).IsOk
            Get
                Return m_IsOK
            End Get
            Set(ByVal value As Boolean)
                m_IsOK = value
            End Set
        End Property
        ''' <summary>
        ''' Übergabe des Ergebnisses (oder Nothing)
        ''' </summary>
        ''' <returns></returns>
        ''' <remarks></remarks>
        Public Property Result() As T Implements IBoolObjectResult(Of T).Result
            Get
                Return m_Result
            End Get
            Set(ByVal value As T)
                m_Result = value
            End Set
        End Property

    End Class


    Public Class testCls

        Public Shared Function CopyFile(ByVal Quelldatei As String, ByVal ZielDatei As String) As BoolResult

            If (Not IO.File.Exists(Quelldatei)) OrElse (String.IsNullOrEmpty(ZielDatei)) Then
                Return New BoolResult(False, "Ungültige Parameterübergabe")
            End If

            Try
                My.Computer.FileSystem.CopyFile(Quelldatei, ZielDatei)
            Catch ex As Exception
                Return New BoolResult(False, ex.Message)
            End Try

            Return New BoolResult(True)
        End Function
    End Class


        Public Shared Function LoadEffects() As OkResult.ObjectResult(Of DataTable)
            Dim res As New OkResult.ObjectResult(Of DataTable)

            Dim path As String = My.Application.Info.DirectoryPath
            Dim file As String = String.Format("{0}\SmsEffekt.xml", path)

            If IO.File.Exists(file) Then
                Try
                    Dim dt As New DataTable
                    dt.ReadXml(file)
                    Return New OkResult.ObjectResult(Of DataTable)(dt, True)
                Catch ex As Exception
                    Return New OkResult.ObjectResult(Of DataTable)(Nothing, False, ex.Message)
                End Try
            End If

            Return New OkResult.ObjectResult(Of DataTable)(Nothing, False, "Datei nicht gefunden " + file)

        End Function

End Namespace