Design and Architecture

Public MustInherit Class VersionedDataObject(Of T As VersionedDataObject(Of T))

    Private _next As T
    Public Property NextVersion() As T
        Get
            Return _next
        End Get
        Set(ByVal value As T)
            If value Is _next Then Exit Property
            _next = value

            If _next Is Nothing Then
                _nextVersions = Nothing
            Else
                _nextVersions = New NextVersionIterator(Me)
            End If
        End Set
    End Property

    Private _nextVersions As IEnumerable(Of T)
    Public ReadOnly Property NextVersions() As IEnumerable(Of T)
        Get
            Return _nextVersions
        End Get
    End Property

    'other common stuff

End Class

// In the Player class
public void play(Dealer dealer)
{
    while(!isBusted() && hit())
    {
        dealer.hit(this);
    }
}

public void addCard(Card card)
{
    hand.addCard(card);
    notifyListeners();
}

public boolean isBusted()
{
    return hand.isBusted();
}

// In the Dealer class
public void hit(Player player)
{
    player.addCard(cards.dealUp());
}