The code changes that we applied to the plugin first declare a class for all of our plugin's functionality and also contain a constructor method for that class. The constructor method is called once, as soon as the class is instantiated by the last line in the plugin's code, and can be used to associate custom functions with all action hooks, filter hooks, and shortcodes.

The main benefit of using an object-oriented approach is that you don't have to be as careful when naming your hook callbacks and all other functions, since these names are local to the class and can be the same as function names declared in any other classes or in procedural PHP code.