Gonzalo Ayuso has a new post to his blog looking at a method for injecting dependencies into your application's code based on comments in the PHPDocumentor-formatted comments of your methods.
Last month I attended to Codemotion conference. I was listening to a talk about Java and I saw the "@inject" decorator. I must admit I switched off my mind from the conference and I started to take notes in my notebook. The idea is to implement something similar in PHP. It's a pity we don't have real decorators in PHP. I really miss them. We need to use PhpDoc. It's not the same than real decorators in other programming languages. That's my prototype. Let's go.
All of the code you'll need to recreate his solution is included - a sample "User" class that needs a valid PDO object in a private "db" property, a "DocInject" class that parses the comments and, using a new feature of PHP 5.4 (traits), injects the needed functionality into the "User" class and creates/assigns the object.