General developer forum

Another example is mod/quiz/renderer.php, which is used for all the student-facing parts of the quiz. (That is, view.php, attempt.php, summary.php and review.php. We have not fixed the editing UI to user a renderer yet.)

The answer is, yes, you should use a renderer, because then any theme can completely override any part of the output if it really wants. It also serves to keep the display code separated from the processing code.

In order to make the separation work, you have to pass all the necessary information into the renderer method. The renderer method then just focusses on generating the HTML required to display that information.

For simple things, you can do that by just passing all the information is as arguments to the method.

Once the number of pieces of information to display gets too large, using separate arguments becomes a nightmare. In that case, a better idea is to use an object so you just have one (or a few) arguments that have named fields. You may either have a convenient object already in existance, if your code is already object-oriented, or you could use a stdClass, or you could define a class specially for the purpose, like https://github.com/timhunt/moodle/blob/master/mod/quiz/renderer.php#L927

If you are defining a class specially, then you can use some magic.

If your class implements Renderable - let us suppose that $links is an instance of the class mod_quiz_links_to_other_attempts, which is renderable - then if you call $renderer->render($links), then it will automagically call the method $renderer->render_mod_quiz_links_to_other_attempts($links) for you. Exactly how useful this magic dispatch is, is open for debate. Anyway, you don't have touse it if you don't want.