require_once is used because our helper functions are defined within a class, and we only want the class defined once.
Our helper class has not been defined yet, but when it is, it will contain one method: getHello(). For our basic example, it is not really necessary to do this - the “Hello, World” message that this method returns could simply be included in the template. We use a helper class here to demonstrate this basic technique.
Our module currently does not use any parameters, but we will pass them to the helper method anyway so that it can be used later if we decide to expand the functionality of our module.
The helper class method is invoked in the following way: