Public Module ItemCache
    Private cacheTable As Hashtable = New Hashtable
    Public Function GetItem(ByVal filename As String) As Item
        SyncLock GetType(ItemCache)
            If cacheTable.ContainsKey(filename.ToLower()) Then
                Return CType(cacheTable(filename.ToLower()), Item)
            End If
            Dim item As Item = New Item(filename)
            cacheTable.Add(filename.ToLower(), item)
            Return item
        End SyncLock
    End Function
End Module