/// <summary>
/// Builds a command that will be able to undo the undo, then perform the undo.
/// </summary>
public override HistoryMemento PerformUndo()
{
HistoryMemento command = new MementoTest(state);
state.SetState(value);
return(command);
}
private void PerformOperation()
{
// Remember current state.
MementoTest mementoTest = new MementoTest(state);
// Perform operation that changes state.
int nextState = state.GetState() + random.Next(-10, 11);
state.SetState(nextState);
// Push old state to stack.
stack.PushNewCommand(mementoTest);
}