Crafting Self-Documenting Code with Explicit Dependencies

Dependency Injection makes software dependencies explicit, enabling self-documenting code.

Inject dependencies to remove unstable knowledge. It’s not the class itself that matters, but the message you send to it. Your classes will be coupled by being mindful of dependencies and injecting them.

This is especially important when a class contains embedded references to a message that will likely change. Isolating the reference provides some insurance against being affected by that change. By injecting dependencies, we can ensure that our code is testable and decoupled, making it easier to reason about and change.

The cost of implementing dependency injection is low, while its benefits are significant.

Define defaults and isolate multi-parameter initialization to make code more transparent. Additionally, some classes are more likely to change than others, not only in your code but also in the code you use.

Depend on things that change less often than you do to create future-proof applications. These principles pave the road to maintenance nirvana.

[¹]: Practical Object-Oriented Design: An Agile Primer Using Ruby