Bloomberg 1© 2024 Bloomberg Finance L.P. All rights reserved. Dependency Injection in C++: A Practical Guide CppCon 2024 September 18, 2024 Pete Muldoon Senior Engineering LeadBloomberg 4 Questions to use it8 Bloomberg Where will we be going ? • Talk will be about inserting meaningful Dependency Injection in applications • Using various DI methods to achieve functionality swapping / instrumentation Code (or just giving up) • Talk is rooted in a real-world system not theory9 Bloomberg Dependency Injection : 1. Decreases coupling between functionality blocks 2. Used to make a class/function independent

1October 3, 2023 2 Libraries: A First Step Toward Standard C++ Dependency Management Bret Brown, C++ Infrastructure Lead, Bloomberg Bill Hoffman, CTO, KitwareHello! Welcome! Bret Brown C++ Infrastructure Projects as portable as the code they contain! ● ✓ Projects should be “cattle,” not “pets”! 7Why dependency management? 8Consensus: 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 10 This could be caused by other root problems!Pain: What’s a dependency bug

1.4.1. Dependency Injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Constructor-based Dependency Injection. . . . . . . . . . 18 Setter-based Dependency Injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Dependency Resolution Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Examples of Dependency Injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2.2. Dependency Injection of Test Fixtures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 3.5.7. Dependency Injection of Test Fixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 Dependency Injection with SpringExtension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

............................................................. 2.1. Inversion of Control / Dependency Injection .......................................................................... 5 3. Beans, BeanFactory ............................................ 10 3.3. Properties, collaborators, autowiring and dependency checking ..................................................................................... constructor arguments detailed ..................................................... 15 3.3.4. Method Injection ...............................................................................................

Framework .............................................................................. 3 2.1. Dependency Injection and Inversion of Control ...................................................... 3 2.2. Framework ........................................................................................... 6 Dependency Management and Naming Conventions ............................................ 9 Spring Dependencies ............................ 11 Maven Dependency Management ............................................................. 11 Maven "Bill Of Materials" Dependency .....................................

...................................................................156 6.8.1. Using AspectJ to dependency inject domain objects with Spring ............................ 156 6.8.2.OtherSpringaspectsforAspectJ name), and started to use the term Dependency Injection. His article then continued to explain the ideas underpinning the Inversion of Control (IoC) and Dependency Injection (DI) principle. If you need a decent insight into IoC and DI, please do refer to said article : http://martinfowler.com/articles/injection.html. Java applications (a loose term which runs the gamut from constrained applets to full-fledged

............................................................. 2.1. Inversion of Control / Dependency Injection .......................................................................... 5 3. Beans, BeanFactory ............................................ 10 3.3. Properties, collaborators, autowiring and dependency checking ..................................................................................... constructor arguments detailed ..................................................... 15 3.3.4. Method Injection ...............................................................................................

............................................................. 2.1. Inversion of Control / Dependency Injection .......................................................................... 5 3. Beans, BeanFactory ............................................ 10 3.3. Properties, collaborators, autowiring and dependency checking ..................................................................................... constructor arguments detailed ..................................................... 15 3.3.4. Method Injection ...............................................................................................

.......................................................... 16 2.1. Inversion of Control / Dependency Injection .......................................................................... 16 3. Beans, BeanFactory ............................................ 21 3.3. Properties, collaborators, autowiring and dependency checking ..................................................................................... constructor arguments detailed ..................................................... 26 3.3.4. Method Injection ...............................................................................................