/// <summary>
/// In the Memento pattern, we need to capture and externalize an object's state so that the object can be
/// restored to that state at a later time. A good example of this is undo/redo operations.
/// </summary>
/// <param name="args"></param>
static void Main(string[] args)
{
//Here's a new supplier for our restaurant
FoodSupplier s = new FoodSupplier();
s.Name = "Harold Karstark";
s.Phone = "(482) 449-1172";
// Let's store that entry in our database.
SupplierMemory m = new SupplierMemory();
m.Memento = s.SaveMemento();
// Continue changing originator
s.Address = "548 S Main St. Nowhere, KS";
// Crap, gotta undo that entry, I entered the wrong address
s.RestoreMemento(m.Memento);
Console.ReadKey();
}
/// <summary>
/// Cancel the action, the command will return the object to its previous state.
/// </summary>
public void Undo()
{
if (_mementos.Count == 0)
{
return;
}
IMemento memento = _mementos.Last();
_mementos.Remove(memento);
Console.WriteLine($"\nSupplierMemory: Restoring state to: {memento.GetName()}");
try
{
_foodSupplier.RestoreMemento(memento);
}
catch (Exception)
{
Undo();
}
}