title: Change object instance propertyChanged when any of its properties get changed
body: <p>I have a simple class. I can change it's properties and get notified. but the object instance property changed does not change when I change any of it's properties. How can I change the object instance property changed to enable the below event to be raised?</p>
  
  <pre><code>public class A : INotifyPropertyChanged
  {
      public event PropertyChangedEventHandler PropertyChanged;
  
      public int _id;
      public int Id
      {
          get { return _id; }
          set
          {
              if (_id == value)
              {
                  return;
              }
  
              _id = value;
              OnPropertyChanged("Id"); 
          }
      }
  
      public string _name;
      public string Name
      {
          get { return _name; }
          set
          {
              if (_name == value)
              {
                  return;
              }
  
              _name = value; 
              OnPropertyChanged("Name"); 
          }
      }
  }
  
  
  
  foreach (INotifyPropertyChanged item in new ObservableCollection&lt;A&gt;() )
           item.PropertyChanged += new PropertyChangedEventHandler(Item_PropertyChanged);
  
      private void Item_PropertyChanged(object sender, PropertyChangedEventArgs e)
      {
  
      }
  </code></pre>