public class Bar : INotifyPropertyChanged
{
  public event PropertyChangedEventHandler PropertyChanged;
  private string foo;
  public string Foo
  {
    get { return this.foo; }
    set
    {
      if(value==this.foo)
        return;
      this.foo = value;
      this.OnPropertyChanged("Foo");
    }
  }
  private void OnPropertyChanged(string propertyName)
  {
    if(this.PropertyChanged!=null)
      this.PropertyChanged(this,new PropertyChangedEventArgs(propertyName));
  }
}

// This is a simple customer class that
// implements the IPropertyChange interface.
public class DemoCustomer  : INotifyPropertyChanged
{
    // These fields hold the values for the public properties.
    private string customerNameValue = String.Empty;

    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged(String info)
    {
        var listeners = PropertyChanged;
        if (listeners  != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }

    public string CustomerName
    {
        get
        {
            return this.customerNameValue;
        }

        set
        {
            if (value != this.customerNameValue)
            {
                this.customerNameValue = value;
                NotifyPropertyChanged("CustomerName");
            }
        }
    }
}