#395 – Overriding the Default add and remove Accessors for an Event

When you use the event keyword to define an event, the compiler automatically creates a private backing variable that is a delegate instance, as well as code that encapsulates adding and removing methods to the delegate’s invocation list.

        public event EventHandler Barked;


You can also explicitly declare the backing variable and the add/remove accessors.  The following code results in equivalent behavior to the code shown above.

        private EventHandler barked;
        public event EventHandler Barked
        {
            add { barked += value; }
            remove { barked -= value; }
        }

To the client code, this looks the same–we just have a Barked event. But you could now add some custom code, e.g. logging.

        private EventHandler barked;
        public event EventHandler Barked
        {
            add
            {
                barked += value;
                Logger.Log(string.Format("Added handler {0} ({1})", value.Method.Name, value.Method.ReflectedType));
            }

            remove
            {
                barked -= value;
                Logger.Log(string.Format("Removed handler {0} ({1})", value.Method.Name, value.Method.ReflectedType));
            }
        }
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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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