VB Shell Programming

Context Menu Handler Interfaces

The components we will write in this book will all implement any given number of system interfaces. “System” in this context (no pun intended) means that these interfaces have already been defined by Microsoft. They are documented, and you can read all about them in the Platform SDK (though the details may be a little murky sometimes).

You can think of an interface as a defined functionality. When a component implements an interface, it is really saying, “I support this functionality!” Consider a Triangle component. It implements the interface Shape. Shape defines two methods: Draw and Color. Therefore, you could expect to access the following functionality through Triangle:

Triangle.Draw
Triangle.Color

Because the Circle, Square, and Trapezoid components also implement Shape, you would expect these objects to have the same functionality as well. This is what it means to implement an interface.

The components in this book all implement some functionality that is required by the shell. This means that when the shell loads our components, it will be able to gain access to our component through a defined mechanism: an interface.

With that said, let’s talk about the interfaces a context menu handler component needs to implement before it can be loaded by the shell.

IShellExtInit

IShellExtInit contains one method (besides the IUnknown portion of the interface), Initialize, as shown in Table 4.1.

Table 4-1. IShellExtInit

Method	Description
Initialize ...