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

Type erasure

The term type erasure describes a pattern in which type information is removed, allowing types that are not necessarily related to be treated in a generic way. This is not something specific to the C++ language. This concept exists in other languages with better support than in C++ (such as Python and Java). There are different forms of type erasure such as polymorphism and using void pointers (a legacy of the C language, which is to be avoided), but true type erasure is achieved with templates. Before we discuss this, let’s briefly look at the others.

The most rudimentary form of type erasure is the use of void pointers. This is typical of C and although possible in C++, it is in no way recommended. It is not type-safe and, therefore, error-prone. However, for the sake of the discussion, let’s have a look at such an approach.

Let’s say we again have knight and mage types and they both have an attack function (a behavior), and we want to treat...