C++ Templates : The Complete Guide - Book Review

After the Effective C++ Serie, I read C++ Templates: The Complete Guide, from David Vandevoorde and Nicolai M. Josuttis

The templates are one of the most powerful feature of C++. However, this is a complex technique that is often misused or misunderstood. This book will help you learning what exactly are templates and how they can be used to improve your software development in C++.

This book is sometimes very technical and is not the easiest to read. Nevertheless, the quality of the information it contains is great. This book covers all the aspects of template programming, from generic programming to template meta programming passing by traits and policy classes.

The first two chapters are introducing function templates and class templates. Then, the third chapter is about the nontype template parameters. Indeed, template parameters can be values and not types. For example, you can pass int constants as template parameters. Then, the two following chapters are more about templates in practice. You will learn the different way to include template code in your common C++ base code. You will also see some tricks useful when developing templates. The last chapter of this first part is fixing a terminology for templates.

The second part of the book (Templates in-Depth) starts with the fundamentals  of templates in-depth. Then, the names in templates are covered in details. After that, we have three very technical and complex chapters. The first covers the instantiations of templates in-depth, the second covers the template argument detection and the next one is about specializations and overloading. The last chapter of this part is about the future directions of the C++ templates. This chapter covers some extensions that have been added to library and compilers,  but were not in C++ standard at the time the book was written. Some of these futures directions are now part of the new C++11 standard.

The next part (Templates and Design) is about the techniques that can be used to improve your software design using templates. The first chapter covers the most common use of templates: compile-time polymorphism. Then, the traits and policy classes are covered. The traits classes are a way to add more information to a template parameter and policy classes represent a configurable behavior for templates. The 16th is talking about some optimization that can be made about templates and inheritance. The next chapter focuses on template metaprogramming. A metaprogram is a program that is not computed at runtime, but at compile-time resulting in performance sometimes very important. Then, the last chapter introduces the expression templates. This technique is a way to encapsulate expressions into templates in order to optimize some computations. The example is about matrix computations.

The final part (Advanced Applications) present four examples in which the templates brings a lot of power. The first example is about type classification. How to know at compile-time of what kind is a given type and makes something depending on the characteristics of the type. The second example is about developing Smart Pointers. The next one presents an implementation of tuples with templates and the last one implements function objects and callbacks. These four examples are not made to be used instead of the standard library, but there are good examples to prove the power of templates.

To conclude, I'll say that this book is a very good guide about templates. It covers most of the details that you can face when developing with templates or when working with very templatized libraries like Boost.

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