title: Where i need to define INotifyPropertyChanged in case of Base and sub classes
body: <p>i have this <code>Base class</code>:</p>
  
  <pre><code>public abstract class WiresharkFile
  {
      protected string _fileName;
      protected int _packets;
      protected int _packetsSent;
      protected string _duration;
  
      public int Packets
      {
          get { return _packets; }
          set { _packets = value; }
      }
  
      public int PacketsSent
      {
          get { return _packetsSent; }
          set { _packetsSent = value; }
      }
  }
  </code></pre>
  
  <p>And this sub class:</p>
  
  <pre><code>public class Libpcap : WiresharkFile, IDisposable, IEnumerable&lt;WiresharkFilePacket&gt;
  {
      ....
  }
  </code></pre>
  
  <p>Create my object:</p>
  
  <pre><code>WiresharkFile wiresahrkFile = new Libpcap(file);
  </code></pre>
  
  <p>My collection:</p>
  
  <pre><code>public ObservableCollection&lt;WiresharkFile&gt; wiresharkFiles { get; set; }
  </code></pre>
  
  <p>Send packets:</p>
  
  <pre><code>wiresahrkFile.Sendpackets();
  </code></pre>
  
  <p>At this point all my <code>wiresahrkFile</code> (<code>Libpcap</code> type) properties is changing so i wonder where i need to define this <code>INotifyPropertyChanged</code>.</p>