Public Class Cliente
    Private _cliente As ICliente

    Public Sub New(ByVal cli As ICliente)
        _cliente = cli
    End Sub

    Public Overridable ReadOnly Property Codice() As String
        Get
            Return IIf(_cliente.Codice Is DBNull.Value, String.Empty, _cliente.Codice.ToString.Trim)
        End Get
    End Property

    Public Overridable ReadOnly Property RagioneSociale() As String
        Get
            Return IIf(_cliente.RagioneSociale Is DBNull.Value, String.Empty, _cliente.RagioneSociale.ToString.Trim)
        End Get
    End Property
End Class

Public Class Clienti
    Inherits CollectionBase

    Protected _adapter As FactoryClienti
    Private _assembly As String
    Protected _filtro As FiltroClienti

    Sub New(ByVal AssemblyName As String)
        _assembly = AssemblyName
        _filtro = New FiltroClienti
        Try
            _adapter = New FactoryClienti(_assembly)
        Catch ex As Exception
            Throw ex
        End Try
        Popola()
    End Sub


    Protected Overridable Sub Popola()
        For Each cl As ICliente In _adapter.GetClienti(_filtro)
            Me.List.Add(New Cliente(CType(cl, ICliente)))
        Next
    End Sub

    'Questo metodo lo uso per filtrare i clienti in base a delle politiche gestite
    Public Overridable Sub Filtra()
        Dim ff As New FiltroClientiForm(_filtro)
        ff.ShowDialog()
        ff.Dispose()
        Me.List.Clear()
        Popola()
    End Sub
End Class

Public Class FiltroClienti
    Implements IFiltroClienti

    Private _Codice As String = ""
    Private _RagioneSociale As String = ""

    Public Property Codice() As String Implements IFiltroClienti.Codice
        Get
            Return _Codice
        End Get
        Set(ByVal value As String)
            _Codice = value
        End Set
    End Property

    Public Property RagioneSociale() As String Implements IFiltroClienti.RagioneSociale
        Get
            Return _RagioneSociale
        End Get
        Set(ByVal value As String)
            _RagioneSociale = value
        End Set
    End Property
End Class