Book Image

C++17 STL Cookbook

By : Jacek Galowicz
Book Image

C++17 STL Cookbook

By: Jacek Galowicz

Overview of this book

C++ has come a long way and is in use in every area of the industry. Fast, efficient, and flexible, it is used to solve many problems. The upcoming version of C++ will see programmers change the way they code. If you want to grasp the practical usefulness of the C++17 STL in order to write smarter, fully portable code, then this book is for you. Beginning with new language features, this book will help you understand the language’s mechanics and library features, and offers insight into how they work. Unlike other books, ours takes an implementation-specific, problem-solution approach that will help you quickly overcome hurdles. You will learn the core STL concepts, such as containers, algorithms, utility classes, lambda expressions, iterators, and more, while working on practical real-world recipes. These recipes will help you get the most from the STL and show you how to program in a better way. By the end of the book, you will be up to date with the latest C++17 features and save time and effort while solving tasks elegantly using the STL.
Table of Contents (18 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Index

Safely postponing initialization with std::call_once


Sometimes we have specific code sections that can be run in parallel context by multiple threads with the obligation that some setup code must be executed exactly once before executing the actual functions. A simple solution is to just execute the existing setup function before the program enters a state from which parallel code can be executed from time to time.

The drawbacks of such an approach are the following ones:

  • If the parallel function comes from a library, the user must not forget to call the setup function. That does not make the library easier to use.
  • If the setup function is expensive in some way, and it might not even need to be executed in case the parallel functions that need this setup are not even always used, then we need code that decides when/if to run it.

In this recipe, we will have a look at std::call_once, which is a helper function that solves this problem for us in a simple to use and elegant implicit way.

How to...