On t Dagfinn Reiersol'sblog, there's a new post that's the second part of a series on "real programming" with the upcoming PHP 5.3 release.

In part one of this series, we looked at the ability to use lambda functions or closures to process arrays. In this part, we will see how closures can be used to build classes in a completely new way. After I did my own research, I discovered that someone had beat me to it.

He compares the two approaches - one defining closures in the constructor, the other as they're needed - and some code showing the creation and use of the lambda functions (using __call and call_user_func_array to catch those requests).