#382 – Handling an Event that Returns Some Data

When you implement an event that returns data, you can use the EventHandler<TEventArgs> delegate type.

When you use the EventHandler<TEventArgs> delegate type, you define a new class that inherits from EventArgs.  A client that wants to handle the new event will need access to this new class.

Suppose that a Dog class implements a Barked event that has the following signature:

        public event EventHandler<BarkedEventArgs> Barked;

You would then add an event handler that accepts two parameters:

  • Parameter of type object, which references the object that raised the event
  • Parameter of type BarkedEventArgs, which contains the data the event wants to pass back

Here’s the complete example:

        static void Main()
        {
            Dog kirby = new Dog("Kirby");
            kirby.Barked += kirby_Barked;

            kirby.Bark("Grrr");
        }

        // Handle the Barked event
        static void kirby_Barked(object o, BarkedEventArgs e)
        {
            Console.WriteLine("Kirby barked: {0}", e.BarkSound);
        }
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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

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