Chapter 3. Typelists

Typelists are a C++ tool for manipulating collections of types. They offer for types all the fundamental operations that lists of values support.

Some design patterns specify and manipulate collections of types, either related by inheritance or not. Notable examples are Abstract Factory and Visitor (Gamma et al. 1995). If you use traditional coding techniques, you can manipulate collections of types by sheer repetition. This repetition leads to a subtle form of code bloating. Most people don't think it could get any better than that. However, typelists let you automate tasks that you usually confine to your editor's macro capability. Typelists bring power from another planet to C++, enabling it to support new, interesting idioms.

This chapter is dedicated to presenting a complete typelist facility for C++, together with a couple of examples of their use. After reading this chapter, you will

• Understanding the typelist concept

• Understand how typelists can be created and processed

• Be able to manipulate typelists effectively

• Know the main uses of typelists and the programming idioms they enable and support

Chapters 9, 10, and 11 use typelists as an enabling technology.