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Hands-On Design Patterns with C++

You're reading from   Hands-On Design Patterns with C++ Solve common C++ problems with modern design patterns and build robust applications

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Product type Paperback
Published in Jul 2023
Publisher Packt
ISBN-13 9781804611555
Length 626 pages
Edition 2nd Edition
Languages
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Author (1):
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Fedor G. Pikus Fedor G. Pikus
Author Profile Icon Fedor G. Pikus
Fedor G. Pikus
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Table of Contents (26) Chapters Close

Preface 1. Part 1: Getting Started with C++ Features and Concepts
2. Chapter 1: An Introduction to Inheritance and Polymorphism FREE CHAPTER 3. Chapter 2: Class and Function Templates 4. Chapter 3: Memory and Ownership 5. Part 2: Common C++ Idioms
6. Chapter 4: Swap – from Simple to Subtle 7. Chapter 5: A Comprehensive Look at RAII 8. Chapter 6: Understanding Type Erasure 9. Chapter 7: SFINAE, Concepts, and Overload Resolution Management 10. Part 3: C++ Design Patterns
11. Chapter 8: The Curiously Recurring Template Pattern 12. Chapter 9: Named Arguments, Method Chaining, and the Builder Pattern 13. Chapter 10: Local Buffer Optimization 14. Chapter 11: ScopeGuard 15. Chapter 12: Friend Factory 16. Chapter 13: Virtual Constructors and Factories 17. Chapter 14: The Template Method Pattern and the Non-Virtual Idiom 18. Part 4: Advanced C++ Design Patterns
19. Chapter 15: Policy-Based Design 20. Chapter 16: Adapters and Decorators 21. Chapter 17: The Visitor Pattern and Multiple Dispatch 22. Chapter 18: Patterns for Concurrency 23. Assessments 24. Index 25. Other Books You May Enjoy

Concepts

C++20 introduced a major enhancement to the C++ template machinery: concepts.

In C++20, templates (both class and function templates), as well as non-template functions (members of class templates, usually) may use a constraint to specify the requirements on template arguments. These constraints are useful to produce better error messages, but they are truly indispensable when there is a need to select a function overload or a template specialization based on some properties of template arguments.

The basic syntax for a constraint is quite simple: a constraint is introduced by the keyword requires which can be specified after the function declaration or before the return type (in this book, we use both ways interchangeably so the reader becomes familiar with different styles of writing code). The expression itself usually uses the template parameters and must evaluate to a boolean value, for example:

// Example 13a
template <typename T> T copy(T&& t...
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