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8849CH16.qxd  10/9/07  4:27 PM  Page 554

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Building the C# Snap-In

Next up, you need to create a type that implements the IAppFunctionality interface. Again, to focus

on the overall design of an extendable application, a trivial type is in order. Assume a new C# Class

Library project named CSharpSnapIn defines a class type named CSharpModule. Given that this class

must make use of the types defined in CommonSnappableTypes, be sure to set a reference to this

binary (as well as System.Windows.Forms.dll to display a noteworthy message). This being said,

here is the code:

using System;

using CommonSnappableTypes;

using System.Windows.Forms;

namespace CSharpSnapIn

{

[CompanyInfo(Name = "Intertech Training",

Url = "www.intertech.com")]

public class CSharpModule : IAppFunctionality

{

void IAppFunctionality.DoIt()

{

MessageBox.Show("You have just used the C# snap in!");

}

}

}

Notice that I choose to make use of explicit interface implementation when supporting the

IAppFunctionality interface. This is not required; however, the idea is that the only part of the

system that needs to directly interact with this interface type is the hosting Windows application.

By explicitly implementing this interface, the DoIt() method is not directly exposed from the

CSharpModule type.