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Template Metaprogramming with C++

You're reading from   Template Metaprogramming with C++ Learn everything about C++ templates and unlock the power of template metaprogramming

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Product type Paperback
Published in Aug 2022
Publisher Packt
ISBN-13 9781803243450
Length 480 pages
Edition 1st Edition
Languages
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Author (1):
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Marius Bancila Marius Bancila
Author Profile Icon Marius Bancila
Marius Bancila
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Table of Contents (16) Chapters Close

Preface 1. Part 1: Core Template Concepts
2. Chapter 1: An Introduction to Templates FREE CHAPTER 3. Chapter 2: Template Fundamentals 4. Chapter 3: Variadic Templates 5. Part 2: Advanced Template Features
6. Chapter 4: Advanced Template Concepts 7. Chapter 5: Type Traits and Conditional Compilation 8. Chapter 6: Concepts and Constraints 9. Part 3: Applied Templates
10. Chapter 7: Patterns and Idioms 11. Chapter 8: Ranges and Algorithms 12. Chapter 9: The Ranges Library 13. Assignment Answers 14. Other Books You May Enjoy Appendix: Closing Notes

Learning more ways to specify constraints

We have discussed in this chapter about requires clauses and requires expressions. Although both are introduced with the new requires keyword, they are different things and should be fully understood:

  • A requires clause determines whether a function participates in overload resolution or not. This happens based on the value of a compile-time Boolean expression.
  • A requires expression determines whether a set of one or more expressions is well-formed, without having any side effects on the behavior of the program. A requires expression is a Boolean expression that can be used with a requires clause.

Let’s see an example again:

template <typename T>
concept addable = requires(T a, T b) { a + b; };
                       // [1] requires expression
template <typename T>
requires addable<T&gt...
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