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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

Class template argument deduction

Before C++17, template argument deduction only worked for functions but not classes. This meant that when a class template had to be instantiated, all the template arguments had to be supplied. The following snippet shows several examples:

template <typename T>
struct wrapper
{
   T data;
};
std::pair<int, double> p{ 42, 42.0 };
std::vector<int>       v{ 1,2,3,4,5 };
wrapper<int>           w{ 42 };

By leveraging template argument deduction for function templates, some standard types feature helper functions that create an instance of the type without the need to explicitly specify template arguments. Such examples are std::make_pair for std::pair and std::make_unique for std::unique_ptr. These helper function templates, used in corroboration with the auto keyword, avoid the need for specifying template arguments for...

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