Once More About Macros in C#

public partial class Window1 : Window
   {
       Person p;
       public Window1()
       {
           InitializeComponent();
           p = new Person();
           DataContext = p;

       }

       private void Button_Click(object sender, RoutedEventArgs e)
       {
           p.LastName.Value = "QuickZip";
           p.Age.Value = 11;
       }


   }

   public class Person : INotifyPropertyChanged
   {
       public Observable<string> LastName { get; set; }
       public Observable<int> Age { get; set; }

       public Person()
       {
           LastName = new Observable<string>();
           Age = new Observable<int>();

           ObservableHelper.RegisterAllObservables(this, NotifyPropertyChanged);
       }

       #region INotifyPropertyChanged Members

       public event PropertyChangedEventHandler PropertyChanged;

       public void NotifyPropertyChanged(string property)
       {
           if (PropertyChanged != null)
               PropertyChanged(this, new PropertyChangedEventArgs(property));
       }

       #endregion
   }


   public static class ObservableHelper
   {
       public static void RegisterAllObservables(object model,  Action<string> notifyPropertyChanged)
       {
           foreach (PropertyInfo pi in model.GetType().GetProperties())
           {
               if (pi.PropertyType.IsGenericType)
                   if (pi.GetValue(model, null) as IObservable != null)
                    {
                        string propertyName = pi.Name;
                        (pi.GetValue(model, null) as IObservable)._notifyPropertyChanged
                           = new Action(delegate
                           {
                               notifyPropertyChanged(propertyName);
                           });
                    }
           }
       }
   }


   internal interface IObservable
   {
       Action _notifyPropertyChanged { get; set; }
   }
   public class Observable<T> : IObservable
   {
       T _value;
       public Action _notifyPropertyChanged { get; set; }

       public T Value
       {
           get { return _value; }
           set
           {
               if (value == null || !value.Equals(_value))
               {
                   _value = value;
                   if (_notifyPropertyChanged != null)
                       _notifyPropertyChanged();
               }
           }
       }

       public override string ToString()
       {
           return Value.ToString();
       }


   }