C#

class BaseModel
{
  internal virtual void OnReceive(EventModel ev)
  {
      if (HandleEvent(ev))
        OnHandle(ev);
  }
  public virtual bool HandleEvent(EventModel ev) { return true;}
  protected virtual void OnHandle(EventModel model) { }
}

public abstract class BaseViewModel
{
    //  Property to specify the View's type. Needs to be set in each VM subclass.
    public ViewTypes ViewType { get; protected set; }

    // CTOR
    public BaseViewModel()
    {
        ViewType = ViewTypes.None;
        AppCore.DataReceived += AppCore_DataReceived;
    }

    // Listens for Data Received.
    public void AppCore_DataReceived(object sender, DataReceivedArgs args)
    {
        // If the ViewModel matches the data model's type...
        if (CanHandleDataReceived(args))
        {
            // Call DataReceived in the subclass
            DataReceived(args);
        }
    }

    // Determines if the subclass can handle the datas received event
    protected virtual bool CanHandleDataReceived(DataReceivedArgs args) 
    {
        return ViewType == args.ViewType; 
    }

    // Subclass method for receiving the data
    protected abstract void DataReceived(DataReceivedArgs args);
}

string input = @"hello world /* this is */ right way to get the index of /* track to */ alpha2 dummy text alpha dummy /* test */textalpha dummy text";
Regex pattern = new Regex(@"\/\*[^\*\/]*\*\/\s+alpha2");
Match match = pattern.Match(input);
if (match.Success)
{
    int theIndex = match.Index;
    ...
}