Most often when I need to sort complex data sets, I'm using some sort of SQL backend. Today I needed to do complex sorting of Reflection objects for some auto generating documentation I'm working on for the upcoming Picora release. [...] In the usort() examples, I had always been under the assumption that the return values had to be 0, 1 or -1. Today I learned that is not true at all, and you can come up with your own scoring system with any range, negative or positive.

He illustrates the point with a simple example showing the sorting of the documentation for Picora. In his protected function, scoreFromMethod, he defines the return array with several values instead of just the one.