Trying to understand WordPress Plugin Boilerplate

Question

I'm new to PHP and WordPress plugin development. In the WordPress Plugin Boilerplate file, includes/class-plugin-name-loader.php, it declares its own add_action function. Is this overriding the default WordPress add_action functions? If so, how do I call the default WordPress add_action function like add_action( 'save_post', 'wpdocs_my_save_post', 10, 3 )

<?php

/**
 * Register all actions and filters for the plugin
 *
 * @link       http://example.com
 * @since      1.0.0
 *
 * @package    Plugin_Name
 * @subpackage Plugin_Name/includes
 */

/**
 * Register all actions and filters for the plugin.
 *
 * Maintain a list of all hooks that are registered throughout
 * the plugin, and register them with the WordPress API. Call the
 * run function to execute the list of actions and filters.
 *
 * @package    Plugin_Name
 * @subpackage Plugin_Name/includes
 * @author     Your Name <[email protected]>
 */
class Plugin_Name_Loader {

    /**
     * The array of actions registered with WordPress.
     *
     * @since    1.0.0
     * @access   protected
     * @var      array    $actions    The actions registered with WordPress to fire when the plugin loads.
     */
    protected $actions;

    /**
     * The array of filters registered with WordPress.
     *
     * @since    1.0.0
     * @access   protected
     * @var      array    $filters    The filters registered with WordPress to fire when the plugin loads.
     */
    protected $filters;

    /**
     * Initialize the collections used to maintain the actions and filters.
     *
     * @since    1.0.0
     */
    public function __construct() {

        $this->actions = array();
        $this->filters = array();

    }

    /**
     * Add a new action to the collection to be registered with WordPress.
     *
     * @since    1.0.0
     * @param    string               $hook             The name of the WordPress action that is being registered.
     * @param    object               $component        A reference to the instance of the object on which the action is defined.
     * @param    string               $callback         The name of the function definition on the $component.
     * @param    int                  $priority         Optional. The priority at which the function should be fired. Default is 10.
     * @param    int                  $accepted_args    Optional. The number of arguments that should be passed to the $callback. Default is 1.
     */
    public function add_action( $hook, $component, $callback, $priority = 10, $accepted_args = 1 ) {
        $this->actions = $this->add( $this->actions, $hook, $component, $callback, $priority, $accepted_args );
    }

    /**
     * Add a new filter to the collection to be registered with WordPress.
     *
     * @since    1.0.0
     * @param    string               $hook             The name of the WordPress filter that is being registered.
     * @param    object               $component        A reference to the instance of the object on which the filter is defined.
     * @param    string               $callback         The name of the function definition on the $component.
     * @param    int                  $priority         Optional. The priority at which the function should be fired. Default is 10.
     * @param    int                  $accepted_args    Optional. The number of arguments that should be passed to the $callback. Default is 1
     */
    public function add_filter( $hook, $component, $callback, $priority = 10, $accepted_args = 1 ) {
        $this->filters = $this->add( $this->filters, $hook, $component, $callback, $priority, $accepted_args );
    }

    /**
     * A utility function that is used to register the actions and hooks into a single
     * collection.
     *
     * @since    1.0.0
     * @access   private
     * @param    array                $hooks            The collection of hooks that is being registered (that is, actions or filters).
     * @param    string               $hook             The name of the WordPress filter that is being registered.
     * @param    object               $component        A reference to the instance of the object on which the filter is defined.
     * @param    string               $callback         The name of the function definition on the $component.
     * @param    int                  $priority         The priority at which the function should be fired.
     * @param    int                  $accepted_args    The number of arguments that should be passed to the $callback.
     * @return   array                                  The collection of actions and filters registered with WordPress.
     */
    private function add( $hooks, $hook, $component, $callback, $priority, $accepted_args ) {

        $hooks[] = array(
            'hook'          => $hook,
            'component'     => $component,
            'callback'      => $callback,
            'priority'      => $priority,
            'accepted_args' => $accepted_args
        );

        return $hooks;

    }

    /**
     * Register the filters and actions with WordPress.
     *
     * @since    1.0.0
     */
    public function run() {

        foreach ( $this->filters as $hook ) {
            add_filter( $hook['hook'], array( $hook['component'], $hook['callback'] ), $hook['priority'], $hook['accepted_args'] );
        }

        foreach ( $this->actions as $hook ) {
            add_action( $hook['hook'], array( $hook['component'], $hook['callback'] ), $hook['priority'], $hook['accepted_args'] );
        }

    }

}

Answer 1

First: Do not use this WordPress Plugin Boilerplate until you learn how to make a WordPress plugin the ordinary WordPress way. The boilerplate you found is complicating things for a beginner.

Google for any beginner document on how to write a wordpress plugin. And read the WordPress official documentation on Actions, Hooks, and Filters. These are sort of the staple for how WordPress works.

Here's a very glossy overview: When you want WordPress to run your plugin, you create an entrypoint function for your plugin. Then you call add_action() to register your function with WordPress. Then WordPress will run your function. Just google for some beginner documentation to learn how to make a plugin and it should show you examples of all this.

Secondly: It looks like the plugin boilerplate is just giving you a pattern for defining a bunch of actions that will be added to the wordpress actions via the foreach loop in the run() function.

There is no overriding going on here. WordPress uses a functional programming paradigm. You don't normally work with objects when you interact with WordPress. Instead, WordPress simply offers a bunch of globally available functions that you call to do things with it. Two of these functions are add_filter() and add_action().

Resource: Here is a link I found that contains a bunch of tutorials and references for creating wordpress plugins: https://www.wpbeginner.com/wp-tutorials/how-to-create-a-wordpress-plugin/