Create Event on Singleton Class

Question

I have a Windows Mobile 6.5 (.net cf 3.5) that uses a singleton class which follows this pattern:

public sealed class Singleton
{
    static readonly Singleton instance=new Singleton();

    // Explicit static constructor to tell C# compiler
    // not to mark type as beforefieldinit
    static Singleton()
    {
    }

    Singleton()
    {
    }

    public static Singleton Instance
    {
        get
        {
            return instance;
        }
    }
}

reference

My class used to collect GPS data from the Intermediate drive. What I want is to create an event on the singleton class that I can subscribe to? E.g. MyClass.Instance.LocationChanged += ...;

Any help would be greatly appreciated.

Mark

Be careful, any code that subscribes the event has to *explicitly* unsubscribe it. Failing to do so causes a memory leak. — Hans Passant, Dec 16 '10 at 15:06

score 3 · Accepted Answer · answered Dec 16 '10 at 15:00

What's the problem?

public sealed class Singleton
{
  ... your code ...

  public delegate LocationChangedEventHandler(object sender, LocationChangedEventArgs ea);  

  public event LocationChangedEventHandler LocationChanged;

  private void OnLocationChanged(/* args */)
  {
    if (LocationChanged != null)
      LocationChanged(this, new LocationChangedEventArgs(/* args */);
  }
}

public class LocationChangedEventArgs : EventArgs
{
  // TODO: implement
}

Call OnLocationChanged whenever you want to fire the event.

aren't you missing a "void" in front of the delegate? – seveves Feb 08 '13 at 14:38 — seveves, Feb 08 '13 at 14:38

score 0 · Answer 2 · answered Dec 16 '10 at 14:59

You should just be able to do this as you would an event on any class.

public event Action<object, EventArgs> LocationChanged;

you can then have a protected virtual method such as:

protected virtual void OnLocationChanged(EventArgs args)
{
   if(LocationChanged != null)
   {
     LocationChanged(this, args);
   }
}

You can fire off your OnLocationChanged method where ever you need too and the event's you've attached will do their thing.

Create Event on Singleton Class

2 Answers2

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