If you’re using function libraries to organize your php code, I highly recommend reading Writing Libraries in PHP on the Zend site. There are a number of very good recommendations as well as insightful discussion of the different approaches available when writing php functions. The author also recommend wrapping you libraries as functions, as I did here. However, he calls his functions as public method calls to an existing object instead of using static calls to a class namespace. No big difference, of course I prefer the later since its more readable.