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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

Expression templates

Expression templates are a metaprogramming technique that enables lazy evaluation of a computation at compile-time. This helps to avoid inefficient operations that occur at runtime. However, this does not come for free, as expression templates require more code and can be cumbersome to read or understand. They are often used in the implementation of linear algebra libraries.

Before seeing how expression templates are implemented, let’s understand what is the problem they solve. For this, let’s suppose we want to do some operations with matrices, for which we implemented the basic operations, addition, subtraction, and multiplication (either of two matrices or of a scalar and a matrix). We can have the following expressions:

auto r1 = m1 + m2;
auto r2 = m1 + m2 + m3;
auto r3 = m1 * m2 + m3 * m4;
auto r4 = m1 + 5 * m2;

In this snippet, m1, m2, m3, and m4 are matrices; similarly, r1, r2, r3, and r4 are matrices that result from performing the...

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