If you've wondered what this "dependency injection" term is that's been floating around the PHP community for a bit now is all about, you should check out this new tutorial on NetTuts.com today. It's a an introduction to the term/functionality and its use in PHP.

Dependency injection has been a frequent subject of discussion among many corporate developers in the past few years. Many feared that they might sacrifice too much time building their application architecture without doing any real work. In this article, I’ll explain why PHP developers should consider taking advantage of dependency injection, when building large, scalable projects.

They start off with the "what" if dependency injection, showing the refactoring of two classes using the "controller injection" method of dependency management. There's also some mention of its ability to help clean up a code base, some of the DI tools that are out there (like Pimple) and some good cases of when to use DI in your app.