Public Class Collection(Of TKey, TValue)
	Private data As List(Of TValue)
	Private keyMapping As Dictionary(Of TKey, Integer)
 
	Public Sub New()
		data = New List(Of TValue)
		keyMapping = New Dictionary(Of TKey, Integer)
	End Sub
 
	Public Sub Add(ByVal item As TValue)
		data.Add(item)
	End Sub
 
	Public Sub Add(ByVal key As TKey, ByVal item As TValue)
		data.Add(item)
		Dim itemIndex As Integer = data.Count - 1
		keyMapping.Add(key, itemIndex)
	End Sub
 
	Default Public Property Item(ByVal index As Integer) As TValue
		Get
			Return data(index)
		End Get
		Set(ByVal value As TValue)
			data(index) = value
		End Set
	End Property
 
	Default Public Property Item(ByVal key As TKey) As TValue
		Get
			Dim itemIndex = keyMapping(key)
			Return data(itemIndex)
		End Get
		Set(ByVal value As TValue)
			Dim itemIndex = keyMapping(key)
			data(itemIndex) = value
		End Set
	End Property
End Class
 
Module Module1
 
	Sub Main()
		Dim testCollection As New Collection(Of String, Integer)
 
		testCollection.Add(1)
		testCollection.Add("Hans", 42)
 
		Console.WriteLine(testCollection.Item("Hans"))
		Console.WriteLine(testCollection(0))
 
		testCollection("Hans") = 11
 
		Console.WriteLine(testCollection(1))
		Console.WriteLine(testCollection("Hans"))
		Console.ReadLine()
	End Sub
 
End Module

Ralf