Book Image

Template Metaprogramming with C++

By : Marius Bancila
5 (1)
Book Image

Template Metaprogramming with C++

5 (1)
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

Understanding the need for concepts

As briefly mentioned in the introduction to this chapter, there are some important benefits that concepts provide. Arguably, the most important ones are code readability and better error messages. Before we look at how to use concepts, let’s revisit an example we saw previously and see how it stands in relation to these two programming aspects:

template <typename T>
T add(T const a, T const b)
   return a + b;

This simple function template takes two arguments and returns their sum. In fact, it does not return the sum, but the result of applying the plus operator to the two arguments. A user-defined type can overload this operator and perform some particular operation. The term sum only makes sense when we discuss mathematical types, such as integral types, floating-point types, the std::complex type, matrix types, vector types, etc.

For a string type, for instance, the plus operator can mean concatenation...