Introduction to Dependency Injection

Overview

Dependency injection is a design pattern that involves supplying dependencies (such as objects, services, or configurations) to a class or function from an external source, rather than having the class create or manage its dependencies internally. It brings the following benefits to the table:

• Decoupling and modularity: Dependency injection promotes loose coupling between the presentation and business logic layers by separating the creation and management of dependencies from the core logic of classes. This improves modularity and makes the codebase easier to maintain and extend.

• Testability: It simplifies unit testing by allowing dependencies to be replaced with mock or test implementations. This facilitates isolated testing of components without relying on complex setups or real external services.

• Code reusability: This technique allows dependencies to be reused across different classes or modules, reducing code duplication and promoting a more modular and scalable architecture.

• Flexibility and configurability: Dependency injection allows for flexibility in configuring and swapping dependencies at runtime, enabling dynamic behavior and customization of application components.

Let’s look at the example of dependency injection:

Basic dependency injection

The basic method to inject dependencies into a class is using the constructor. We pass the desired dependencies in the class constructor and are good to go. Here’s how: