#374 – A Custom Delegate Derives from System.MulticastDelegate

You define a new delegate in C# using the delegate keyword.

        private delegate void StringHandlerDelegate(string s);

This is equivalent to defining a new class that inherits from System.MulticastDelegate (which in turn inherits from System.Delegate).  MulticastDelegate is a class that knows how to refer to a set of methods–known as as the delegates invocation list.

Later in your code, you declare an instance of your delegate and set it equal to a method.

            StringHandlerDelegate del = Method1;

When you do this, you’re creating an instance of the new MulticastDelegate subclass and giving it a reference to the Method1 method.

You can also add a second method to the invocation list using the += operator.

            del += Method2;

At this point, a new delegate is created and System.Delegate.Combine method is then called to combine the two delegates into a new delegate that points to both methods.

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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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