#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 software development and sailing.

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