Should I make a library, module or singleton class...

[eluser]esra[/eluser]
Another alternative is the Khaos Event Manager library. I have not tried this myself, but it is supposed to be similar to the plugin system used in Joomla which works really nice. Correct me if I'm wrong, but I believe you should be able to trigger an event from any controller within one or more methods, Event Manager listens for the event, then Event Manager executes code in a plugin associated with the event. There is very little documentation for this library, but the Joomla developer docs should give you a good idea of the potential of this library.

I use the Base Controller approach myself. In some base controllers, I add helper code after the closing brace for the base controller class when the helper functions are required by all controllers. However, the helper functions could just as well been loaded from a separate helper file.