This print for content only-size & color not accurate 7" X 9-1/4" / casebound / malloy

// Not bothering to create a System.EventArgs

// derived type here.

public delegate void MathMessage(string msg);

public event MathMessage ComputationFinished;

public int Add(int x, int y)

{

ComputationFinished("Adding complete.");

return x + y;

}

public int Subtract(int x, int y)

{

ComputationFinished("Subtracting complete.");

return x - y;

}

}

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8849CH11.qxd  10/1/07  10:43 AM  Page 372

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If we are not using anonymous method syntax, you know that the way we would handle the

ComputationComplete event is as follows:

class Program

{

static void Main(string[] args)

{

SimpleMath m = new SimpleMath();

m.ComputationFinished +=

new SimpleMath.MathMessage(ComputationFinishedHandler);

Console.WriteLine("10 + 10 is {0}", m.Add(10, 10));

Console.ReadLine();

}

static void ComputationFinishedHandler(string msg)

{ Console.WriteLine(msg); }

}

However, we can register the event handler with a specific event like this (the remainder of the

code is identical):

m.ComputationFinished += ComputationFinishedHandler;

Notice that we are not directly allocating the associated delegate object, but rather simply

specifying a method that matches the delegate’s expected signature (a method returning void and

taking a single System.String in this case). Understand that the C# compiler is still ensuring type

safety. Thus, if the ComputationFinishedHandler() method did not take a System.String and return

void, we would be issued a compiler error.

It is also possible to explicitly convert an event handler into an instance of the delegate it

relates to. This can be helpful if you need to obtain the underlying delegate to interact with the

inherited members of System.MulticastDelegate. For example: