CHAPTER 8
Working with Interfaces
This chapter builds upon your current understanding of object-oriented development by examining the
topic of interface-based programming. Here you’ll learn how to define and implement interfaces, and
come to understand the benefits of building types that support multiple behaviors. Along the way, I’ll
also discuss a number of related topics, such as obtaining interface references, explicit interface
implementation, and the construction of interface hierarchies. We’ll also examine a number of standard
interfaces defined within the .NET base class libraries. As you will see, your custom classes and
structures are free to implement these predefined interfaces to support a number of useful behaviors,
such as object cloning, object enumeration, and object sorting.
Understanding Interface Types
To begin this chapter, allow me to provide a formal definition of the interface type. An interface is
nothing more than a named set of abstract members. Recall from Chapter 6 that abstract methods are
pure protocol in that they do not provide a default implementation. The specific members defined by an
interface depend on the exact behavior it is modeling. Said another way, an interface