If you decide to namespace your own extension you will need an autoloader for J3. J4 has its own autoloader and as long as you put the proper namespace details in the extension xml file the installer will automatically insert your namespace into the Joomla autoloader.


Under J3 you have 2 options. You can create a system plugin that autoloads your classes in an onAfterInitialise function, or you can create an autoloader file that your extension includes as part of the very early running of it, i.e. in your extension constructor or controller.