[Software Development] Using The Repository Pattern in WordPress

00-repository.php

<?php

/**
 * Serves as a registry for all objects that need to be accessed globally throughout the
 * plugin.
 */
class Registry
{

  /**
   * @var array The array used to the the various objects that will be used in the plugin.
   */
  private $storage;

  /**
   * Initializes the plugin by creating an instance of an empty array.
   */
  public function __construct()
  {
      $this->storage = [];
  }

  /**
   * Adds an instance of a class to the registry's storage array using the given key
   *
   * @param string $id    The ID of the object to be used to retrieve it later in the plugin.
   * @param mixed  $class An instance of the class that will be associated with the specified key.
   */
  public function add($id, $class)
  {
      $this->storage[$id] = $class;
  }

  /**
   * @param string $id    The ID of the object to retrieve from the repository.
   * @return mixed $class An instance of the class associated with the specified key (or null if it doesn't exist).
   */
  public function get($id)
  {
      return array_key_exists($id, $this->storage) ? $this->storage[$id] : null;
  }
}

01-register-repository.php

<?php

/**
 * Creates a Registry using the Registry Design Pattern to store objects
 * that can be used throughout the plugin.
 *
 */
$registry = new Registry();
add_filter('acmeRegistry', function () use ($registry) {
  return $registry;
});

02-adding-data.php

<?php

/**
 * Get an reference to the repository and add an instance of a 
 * PostManager to it. The PostManager is a class that allows us
 * to manipulate posts.
 */
$this->registry = apply_filters('acmeRegistry', null);
$this->registry->add('postManager', new PostManager());

03-using-data.php

<?php

/**
 * Get an reference to the repository, get a reference to the PostManager
 * then you can begin working with it.
 */
$this->registry = apply_filters('acmeRegistry', null);
$this->registry->add('postManager', new PostManager());

// An example call that you can make to set the title of the post.
$postManager->updateTitle('This Is the New Title');