Introduction Dependency injection, often shortened to the acronym DI, is a fundamental principle of software design. Every software developer makes decisions related dependency injection whether they are aware of it or not, and most, if not all developers, have had to deal with the consequences of poor DI-related decisions in an existing code base. Understanding it and deciding when and how to use it is crucial to building good software. In this article, we define DI, discuss its purpose and benefits, and when and when not to use it. By learning these principles, we can write higher-quality, more maintainable code and even ship code faster. This article uses the Java programming language for examples. The general principles of DI, however, apply to any general-purpose programming language. Definition of DI Dependency injection is the act of providing dependencies to code. The opposite of dependency injection is to have code explicitly access its dependencies via global va...
Introduction Software development velocity is a major concern for many teams and tech companies. Software is expensive to write and maintain. Businesses find themselves under siege by competition and feel pressure to move more quickly. In this article, I am going to discuss how we can move faster as developers by removing unnecessary dependencies, such as runtime DI frameworks like Spring. When designing a professional race car, one builds around the engine entirely. The engine is the heaviest component of the vehicle, but also the most important, as it provides all the power to propel the rest of the vehicle forward. All other components are designed to support the engine but otherwise get out of the way. By analogy, a service implements and executes some key business functionality, which we can compare to our race car's engine. Any frameworks, libraries, and infrastructure we use must support the core business functions of the service, but hopefully otherwise get out of ...