Memento

namespace Core.Interfaces
{
    public interface IOriginator<TMemento> where TMemento : IMemento
    {
        TMemento SaveState();
        void RestoreState(TMemento memento);
    }
}

namespace Core.Interfaces
{
    public interface IMemento
    {
        object State { get; }
    }

    public interface IMemento<out TState> : IMemento
    {
        new TState State { get; }
    }
}