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 able 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 Production 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

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

Gradually replacing auto-configuration Disabling specific auto-configuration 17. Spring Beans and dependency injection 18. Using the @SpringBootApplication annotation 19. Running your application Running using Gradle Configuring Gradle to produce a pom that inherits dependency management Configuring Gradle to produce a pom that imports dependency management 60. Supporting other build systems Repackaging use with Maven Configuring Spring Loaded for use with Gradle and IntelliJ 73. Build Customize dependency versions with Maven Create an executable JAR with Maven Create an additional executable JAR Extract

Gradually replacing auto-configuration Disabling specific auto-configuration 17. Spring Beans and dependency injection 18. Using the @SpringBootApplication annotation 19. Running your application Running using Gradle Configuring Gradle to produce a pom that inherits dependency management Configuring Gradle to produce a pom that imports dependency management 60. Supporting other build systems Repackaging use with Maven Configuring Spring Loaded for use with Gradle and IntelliJ 73. Build Customize dependency versions with Maven Create an executable JAR with Maven Create an additional executable JAR Extract

Gradually replacing auto-configuration Disabling specific auto-configuration 17. Spring Beans and dependency injection 18. Using the @SpringBootApplication annotation 19. Running your application Running using Gradle Configuring Gradle to produce a pom that inherits dependency management Configuring Gradle to produce a pom that imports dependency management 60. Supporting other build systems Repackaging use with Maven Configuring Spring Loaded for use with Gradle and IntelliJ 73. Build Customize dependency versions with Maven Create an executable JAR with Maven Create an additional executable JAR Extract

Gradually replacing auto-configuration Disabling specific auto-configuration 17. Spring Beans and dependency injection 18. Using the @SpringBootApplication annotation 19. Running your application Running using Gradle Configuring Gradle to produce a pom that inherits dependency management Configuring Gradle to produce a pom that imports dependency management 60. Supporting other build systems Repackaging use with Maven Configuring Spring Loaded for use with Gradle and IntelliJ 73. Build Customize dependency versions with Maven Create an executable JAR with Maven Create an additional executable JAR Extract

Gradually replacing auto-configuration Disabling specific auto-configuration 17. Spring Beans and dependency injection 18. Using the @SpringBootApplication annotation 19. Running your application Running using Gradle Configuring Gradle to produce a pom that inherits dependency management Configuring Gradle to produce a pom that imports dependency management 60. Supporting other build systems Repackaging use with Maven Configuring Spring Loaded for use with Gradle and IntelliJ 73. Build Customize dependency versions with Maven Create an executable JAR with Maven Create an additional executable JAR Extract

Gradually replacing auto-configuration Disabling specific auto-configuration 17. Spring Beans and dependency injection 18. Using the @SpringBootApplication annotation 19. Running your application Running dependencies Deduced “grab” coordinates Default import statements Automatic main method Custom dependency management Testing your code Applications with multiple source files Packaging your application plugin Packaging executable jar and war files 62. Spring Boot Gradle plugin Including the plugin Dependency management Packaging executable jar and war files Running a project in-place Spring Boot plugin

Gradually replacing auto-configuration Disabling specific auto-configuration 17. Spring Beans and dependency injection 18. Using the @SpringBootApplication annotation 19. Running your application Running using Gradle Configuring Gradle to produce a pom that inherits dependency management Configuring Gradle to produce a pom that imports dependency management 60. Supporting other build systems Repackaging use with Maven Configuring Spring Loaded for use with Gradle and IntelliJ 73. Build Customize dependency versions with Maven Create an executable JAR with Maven Create an additional executable JAR Extract

example Creating an executable jar 12. What to read next III. Using Spring Boot 13. Build systems Dependency management Maven Inheriting the starter parent Using Spring Boot without the parent POM Changing Gradually replacing auto-configuration Disabling specific auto-configuration 17. Spring Beans and dependency injection 18. Using the @SpringBootApplication annotation 19. Running your application Running dependencies Deduced “grab” coordinates Default import statements Automatic main method Custom dependency management Testing your code Applications with multiple source files Packaging your application