Chapter 11. Interfaces

Chapter 11. Interfaces

The previous few chapters have explained class modules in some depth and the various parts they can play in our applicationshandling events, encapsulating functionality and creating our own object models. We've seen that userforms and the workbook and worksheet code modules are just special types of class module. This chapter takes a step further into object-oriented design by explaining how one class can appear to be many different types of object and how many different classes can appear to be the same type of object. We show that by using the techniques explained in this chapter, we can improve the robustness of our solution, simplify the development experience and reduce the amount of code we need to write. As an example, we convert our central consolidation and reporting application to use a plug-in architecture for its userforms, enabling us to extend the application without having to add any more code to the core routines.