Book Image

Modern C++ Programming Cookbook - Second Edition

By : Marius Bancila
5 (1)
Book Image

Modern C++ Programming Cookbook - Second Edition

5 (1)
By: Marius Bancila

Overview of this book

C++ has come a long way to be one of the most widely used general-purpose languages that is fast, efficient, and high-performance at its core. The updated second edition of Modern C++ Programming Cookbook addresses the latest features of C++20, such as modules, concepts, coroutines, and the many additions to the standard library, including ranges and text formatting. The book is organized in the form of practical recipes covering a wide range of problems faced by modern developers. The book also delves into the details of all the core concepts in modern C++ programming, such as functions and classes, iterators and algorithms, streams and the file system, threading and concurrency, smart pointers and move semantics, and many others. It goes into the performance aspects of programming in depth, teaching developers how to write fast and lean code with the help of best practices. Furthermore, the book explores useful patterns and delves into the implementation of many idioms, including pimpl, named parameter, and attorney-client, teaching techniques such as avoiding repetition with the factory pattern. There is also a chapter dedicated to unit testing, where you are introduced to three of the most widely used libraries for C++: Boost.Test, Google Test, and Catch2. By the end of the book, you will be able to effectively leverage the features and techniques of C++11/14/17/20 programming to enhance the performance, scalability, and efficiency of your applications.
Table of Contents (16 chapters)
13
Bibliography
14
Other Books You May Enjoy
15
Index

Using requires expressions and clauses

In the previous recipe, we introduced the topic of concepts and constraints, and learned about them with the help of several examples that were solely based on already existing type traits. Moreover, we also used the terser syntax for specifying concepts, with the concept name used instead of the typename or the class keyword in the template declaration. However, it is possible to define more complex concepts with the help of requires expressions. These are prvalues of the type bool that describe the constraints on some template arguments.

In this recipe, we will learn how to write requires expressions and an alternative way to specify constraints on template arguments.

Getting ready

The class template NumericalValue<T> and the function template wrap() defined in the previous recipe will be used in the code snippets presented in this recipe.

How to do it...

To specify requirements for template arguments, you can use...