Till Klampaeckel has a new post to his blog looking dependency injection containers for PHP and some of the concepts that come with them. No specific tools are advocated, but it's a good introduction to DI if you haven't had much exposure (and his view on why you may not want to use it).

I got into a discussion on Twitter the other day where I mentioned that I don't like DI. Call it lack of sleep or language barrier (on my part), but I said DI - dependency injection - when I meant the dependency injection container. Having said this, let me explain why I don't like it.

He talks about all of the hype surrounding dependency injection right now and some of the more realistic questions to ask before you think about using this approach. He sees DI containers as more extra overhead that an application might not even need. He compares it to using a "registry" and talks about some of the downsides such as:

• Moving away the obvious dependencies from an object makes applications complicated, harder to understand
• Convention over configuration usually clashes with the approach DI containers advocate.
• Missing support in IDEs.
• Inline code documentation - people don't even get __call() etc. right.