Book Image

Template Metaprogramming with C++

By : Marius Bancila
Book Image

Template Metaprogramming with C++

By: Marius Bancila

Overview of this book

Learn how the metaprogramming technique enables you to create data structures and functions that allow computation to happen at compile time. With this book, you'll realize how templates help you avoid writing duplicate code and are key to creating generic libraries, such as the standard library or Boost, that can be used in a multitude of programs. The introductory chapters of this book will give you insights into the fundamentals of templates and metaprogramming. You'll then move on to practice writing complex templates and exploring advanced concepts such as template recursion, template argument deduction, forwarding references, type traits, and conditional compilation. Along the way, you'll learn how to write variadic templates and how to provide requirements to the template arguments with C++20 constraints and concepts. Finally, you'll apply your knowledge of C++ metaprogramming templates to implement various metaprogramming patterns and techniques. By the end of this book, you'll have learned how to write effective templates and implement metaprogramming in your everyday programming journey.
Table of Contents (16 chapters)
Part 1: Core Template Concepts
Part 2: Advanced Template Features
Part 3: Applied Templates
Appendix: Closing Notes

Chapter 3: Variadic Templates

A variadic template is a template with a variable number of arguments. This is a feature that was introduced in C++11. It combines generic code with functions with variable numbers of arguments, a feature that was inherited from the C language. Although the syntax and some details could be seen as cumbersome, variadic templates help us write function templates with a variable number of arguments or class templates with a variable number of data members in a way that was not possible before with compile time evaluation and type safety.

In this chapter, we will learn about the following topics:

  • Understanding the need for variadic templates
  • Variadic function templates
  • Parameter packs
  • Variadic class templates
  • Fold expressions
  • Variadic alias templates
  • Variadic variable templates

By the end of the chapter, you will have a good understanding of how to write variadic templates and how they work.

We will start, however...