If you have ever used a web browser, you are already familiar with the concept of a History List. When you press your browser's Back button, you return the previous page you viewed. Similarly, when you press the Next button, you move to the page after the one you are currently on.
This class implements the History List mechanism as a set of two stacks:
By maintaining these two stacks, the class keeps a history list that allows you to move back and forth through a history of items.
|(Declarations)||Declarations||Declarations and private variables for the CHistoryList class.|
|BackEnabled||Property||Determine whether Back should be enabled.|
|CurrentItem||Property||Get the current item from the history list.|
|ForwardEnabled||Property||Determine whether Forward should be enabled.|
|MaxItems||Property||Get the maximum number of items that can be added to the history list.|
|Class_Initialize||Initialize||Set initial values to defaults which may be overridden with property settings.|
|Add||Method||Add an item to the history list.|
|Back||Method||Move back in the history list.|
|EnumerateBack||Method||Enumerate the items available with the back method.|
|EnumerateForward||Method||Enumerate the items available with the forward method.|
|Forward||Method||Move forward in the history list.|
|GetItem||Private||Get an item in the history list.|
' Example of CHistoryList ' ' To try this example, do the following: ' 1. Create a new form ' 2. Add a command button named 'cmdTest' ' 3. Paste all the code from this example to the new form's module ' 4. Run the form Private HistoryList As CHistoryList Private Sub cmdTest_Click() Dim varItem As Variant Dim varItems() As Variant ' Instantiate the History List variable Set HistoryList = New CHistoryList ' Override the standard MaxItems property to allow 10 items on the list HistoryList.MaxItems = 10 HistoryList.Add "A" HistoryList.Add "B" HistoryList.Add "C" HistoryList.Add "D" HistoryList.Add "E" HistoryList.Add "F" HistoryList.Back HistoryList.Back HistoryList.Back Debug.Print HistoryList.CurrentItem HistoryList.Forward Debug.Print HistoryList.CurrentItem Debug.Print "Back Items: " HistoryList.EnumerateBack varItems For Each varItem In varItems Debug.Print varItem Next varItem Debug.Print "Forward Items: " HistoryList.EnumerateForward varItems For Each varItem In varItems Debug.Print varItem Next varItem End Sub
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