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// .NET delegates can also point to instance methods as well.

SimpleMath m = new SimpleMath();

BinaryOp b = new BinaryOp(m.Add);

// Show information about this object.

DisplayDelegateInfo(b);

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

Console.ReadLine();

}

In this case, we would find the output shown in Figure 11-3.

Figure 11-3.

Examining a delegate’s invocation list (once again)

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Source Code

The SimpleDelegate project is located under the Chapter 11 subdirectory.

Retrofitting the Car Type with Delegates

Clearly, the previous SimpleDelegate example was intended to be purely illustrative in nature, given

that there would be no reason to build a delegate simply to add two numbers. To provide a more

realistic use of delegate types, let’s retrofit the Car type created in Chapter 9 to send notifications

using .NET delegates rather than a custom callback interface. Beyond no longer implementing

IEngineNotification, here are the basic steps we will need to take:

• Define new delegate types that will send notifications to the caller.

• Declare a member variable of these delegate types in the Car class.

• Create helper functions on the Car that allow the caller to set the methods maintained by the

delegate member variables.

• Update the Accelerate() method to invoke the delegate’s invocation list under the correct

circumstances.

C H A P T E R   1 1  

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D E L E G AT E S, E V E N T S, A N D   L A M B D A S

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To begin, create a new Console Application project named CarDelegate and insert your

previous Car and Radio definitions from the CallbackInterface example of Chapter 9 (you may

wish to change the namespace containing these types to the current project name or import the

CallbackInterface namespace as an alternative). Consider the following updates to the Car class,

which address the first three points:

public class Car

{