Microsoft® Visual Studio® 2010 Unleashed

The Structure of an Add-in

The first thing to notice is that the Connect class inherits from two different interfaces: IDTCommandTarget and IDTExtensibility2.

public class Connect : IDTExtensibility2, IDTCommandTarget

The IDTCommandTarget interface provides the functionality necessary to expose the add-in via a command bar. The code to inherit from this interface was added by the wizard because the Yes, Create a Tools Menu Item box was checked on page 4 of the add-in wizard.

The IDTExtensibility2 interface provides the eventing glue for add-ins. It is responsible for all the events that constitute the life span of an add-in.