Although the operations are simple, it is vital that they be handled correctly. It is generally a poor principle to allow access to the mechanisms of a system rather than providing an interface through class methods. The latter approach ideally allows the creation of a robust interface that changes relatively infrequently, while details of implementation can be modified without affecting the rest of the system.

Their code includes methods to get all roles for a user, check to see which they are permitted to use, add a "permit" role and remove it back out. The tutorial is an excerpt from the Packt book PHP5 CMS Framework Development (Martin Brampton).