## 20 24 September 15 - 20 ## +24 ## Dependency Injection in C++ A Practical Guide ## PETER MULDOON # Dependency Injection in C++: A Practical Guide Engineering CppCon 2024 September 18, 2024 Pete away and be able to use it ## Where will we be going? - Talk will be about inserting meaningful Dependency Injection in applications - Using various DI methods to achieve functionality swapping / instrumentation (or just giving up) • Talk is rooted in a real-world system not theory ## Basic Definitions ## Dependency Injection : 1. Decreases coupling between functionality blocks 2. Used to make a class/function

First Step Toward Standard C++ Dependency Management ## BILL HOFFMAN & BRET BROWN ## 20 23 October 01 - 06 ## Libraries: A First Step Toward Standard C++ Dependency Management October 3, 2023 Bloomberg Projects as portable as the code they contain! ✓ Projects should be “cattle,” not “pets”! ## Why dependency management? Consensus: Managing dependencies == way too hard Q: Which of these do you find frustrating What's a dependency bug? Missing interfaces: fangorn.cxx:2:10: fatal error: jsonlog/core.hxx: No such file or directory This could be caused by other root problems! Pain: What's a dependency bug?

. 1.2. Usage scenarios ..... 2. Background information ..... 2.1. Inversion of Control / Dependency Injection ..... 3. Beans, BeanFactory and the ApplicationContext ..... 3.1. Introduction . 3.2.5. To singleton or not to singleton ..... 3.3. Properties, collaborators, autowiring and dependency checking ..... 3.3.1. Setting bean properties and collaborators ..... 3.3.2. Constructor Argument 22.2. Integration testing ..... 247 22.2.1. Context management and caching ..... 248 22.2.2. Dependency Injection of test class instances ..... 248 22.2.3. Transaction management ..... 248 22.2.4

Next ..... 21 6. Developing with Spring Boot ..... 23 6.1. Build Systems ..... 23 6.1.1. Dependency Management ..... 23 6.1.2. Maven ..... 23 6.1.3. Gradle ..... 23 6.1.4. Ant ..... 24 6 ... 32 6.4.2. Disabling Specific Auto-configuration Classes ..... 32 6.5. Spring Beans and Dependency Injection ..... 33 6.6. Using the @SpringBootApplication Annotation ..... 35 6.7. Running Your 226 7.10.3. Kotlin API ..... 226 runApplication ..... 226 Extensions ..... 227 7.10.4. Dependency management ..... 227 7.10.5. @ConfigurationProperties ..... 227 7.10.6. Testing ..... 228

What to Read Next ..... 22 III. Using Spring Boot ..... 23 13. Build Systems ..... 24 13.1. Dependency Management ..... 24 13.2. Maven ..... 24 Inheriting the Starter Parent ..... 25 Using ..... 36 16.2. Disabling Specific Auto-configuration Classes ..... 36 17. Spring Beans and Dependency Injection ..... 37 18. Using the @SpringBootApplication Annotation ..... 38 19. Running Your ... 188 48.3. Kotlin API ..... 189 runApplication ..... 189 Extensions ..... 189 48.4. Dependency management ..... 189 48.5. @ConfigurationProperties ..... 190 48.6. Testing ..... 190 48

. 1.2. Usage scenarios ..... 2. Background information ..... 2.1. Inversion of Control / Dependency Injection ..... 3. Beans, BeanFactory and the ApplicationContext ..... 3.1. Introduction . 3.2.5. To singleton or not to singleton ..... 3.3. Properties, collaborators, autowiring and dependency checking ..... 3.3.1. Setting bean properties and collaborators ..... 3.3.2. Constructor Argument 21.2. Integration testing ..... 221 21.2.1. Context management and caching ..... 222 21.2.2. Dependency Injection of test class instances ..... 222 21.2.3. Transaction management ..... 222 21.2.4

. 1.2. Usage scenarios ..... 2. Background information ..... 2.1. Inversion of Control / Dependency Injection ..... 3. Beans, BeanFactory and the ApplicationContext ..... 3.1. Introduction . 3.2.5. To singleton or not to singleton ..... 3.3. Properties, collaborators, autowiring and dependency checking ..... 3.3.1. Setting bean properties and collaborators ..... 3.3.2. Constructor Argument 22.2. Integration testing ..... 254 22.2.1. Context management and caching ..... 255 22.2.2. Dependency Injection of test class instances ..... 255 22.2.3. Transaction management ..... 255 22.2.4

. 1.2. Usage scenarios ..... 2. Background information ..... 2.1. Inversion of Control / Dependency Injection ..... 3. Beans, BeanFactory and the ApplicationContext ..... 3.1. Introduction . 3.2.5. To singleton or not to singleton ..... 3.3. Properties, collaborators, autowiring and dependency checking ..... 3.3.1. Setting bean properties and collaborators ..... 3.3.2. Constructor Argument 23.2. Integration testing ..... 266 23.2.1. Context management and caching ..... 267 23.2.2. Dependency Injection of test class instances ..... 267 23.2.3. Transaction management ..... 267 23.2.4

. 1.2. Usage scenarios ..... 2. Background information ..... 2.1. Inversion of Control / Dependency Injection ..... 3. Beans, BeanFactory and the ApplicationContext ..... 3.1. Introduction . 3.2.5. To singleton or not to singleton ..... 3.3. Properties, collaborators, autowiring and dependency checking ..... 3.3.1. Setting bean properties and collaborators ..... 3.3.2. Bean properties Spring Framework The Core package is the most fundamental part of the framework and provides the Dependency Injection features allowing you to manage bean container functionality. The basic concept here

. 1.2. Usage scenarios ..... 2. Background information ..... 2.1. Inversion of Control / Dependency Injection ..... 3. Beans, BeanFactory and the ApplicationContext ..... 3.1. Introduction . 3.2.5. To singleton or not to singleton ..... 3.3. Properties, collaborators, autowiring and dependency checking ..... 3.3.1. Setting bean properties and collaborators ..... 3.3.2. Constructor Argument 20.2. Integration testing ..... 202 20.2.1. Context management and caching ..... 203 20.2.2. Dependency Injection of test class instances ..... 203 20.2.3. Transaction management ..... 203 20.2.4