[WordPress] Rapid Prototyping: Prototype To Code, Part 2

00-post-messenger.php

<?php
/**
 * Display content for the meta box when requested.
 *
 * @author Tom McFarlin
 * @since  0.2.0
 */

namespace McFarlin\TRP\Utility;
use McFarlin\TRP\Utility\Post_Query;

/**
 * Retrieves information from the class responsible for querying the database and
 * renders it in the context of our meta box when called via the Meta Box Display.
 *
 * @author Tom McFarlin
 * @since  0.2.0
 */
class Post_Messenger {
  // Snip for brevity. 
}

01-post-messenger.php

<?php

/**
 * Instantiates the class by setting a reference to the query.
 *
 * @param string $plugin_dir The path to the root of the plugin directory.
 */
public function __construct( $plugin_dir ) {

	$this->query      = new Post_Query();
	$this->plugin_dir = trailingslashit( $plugin_dir );
}

02-post-messenger.php

<?php

/**
 * Displays the description of the content of the meta box.
 *
 * @access private
 */
private function get_post_message() {
	include_once $this->plugin_dir . 'Display/Views/post-list.php';
}

/**
 * Displays the description of the content of the meta box.
 *
 * @access private
 */
private function get_description() {
	include_once $this->plugin_dir . 'Display/Views/message-description.php';
}

/**
 * Displays a message of there are no recent posts.
 *
 * @access private
 */
private function get_no_posts_message() {
	include_once $this->plugin_dir . 'Display/Views/no-post-list.php';
}

03-post-query.php

<?php

namespace McFarlin\TRP\Utility;

/**
 * Queries the database for three most recent posts. Returns the query to the
 * caller so that it can be interrogates for posts or not.
 *
 * @author Tom McFarlin
 * @since  0.2.0
 */
class Post_Query {

  // Snip for brevity.
  
	private function get_posts() {

		$args = array(
			'post_type'   	 => 'post',
			'post_status' 	 => 'publish',
			'posts_per_page' => 3,
			'orderby'     	 => 'date',
			'order'       	 => 'desc',
		);
		$this->query = new \WP_Query( $args );

		return $this->query;
	}
}

04-meta-box.php

<?php

 namespace McFarlin\TRP\Display;
 use McFarlin\TRP\Display\Meta_Box_Display;

/**
 * Registers the Meta Box with WordPress. Defines the ID, title, display function,
 * and the post type on which it will live.
 *
 * @author Tom McFarlin
 * @since  0.2.0
 */
class Meta_Box {

	/**
	 * A reference to the class that will display the contents in the meta box.
	 *
	 * @access private
	 * @var    Meta_Box_Display
	 */
	private $meta_box_display;

	/**
	 * Instantiates the class by setting its property equal to a reference to its display.
	 *
	 * @param string $plugin_dir A reference to the root of the plugin's directory.
	 */
	public function __construct( $plugin_dir ) {
		$this->meta_box_display = new Meta_Box_Display( $plugin_dir );
	}
  
	// Snip for brevity.
}

05-meta-box-display.php

<?php
/**
 * Defines the display for the meta box.
 *
 * @author Tom McFarlin
 * @since  0.2.0
 */

namespace McFarlin\TRP\Display;
use McFarlin\TRP\Utility\Post_Messenger;

/**
 * Defines the display for the meta box that will render the content in the
 * context of its meta box.
 *
 * @author Tom McFarlin
 * @since  0.2.0
 */
class Meta_Box_Display {

	/**
	 * A reference to the class that will display the contents in the meta box.
	 *
	 * @access private
	 * @var    Post_Messenger
	 */
	private $messenger;

	/**
	 * Instantiates the object by setting a property equal to that of the class
	 * responsible for rendering the messages from the post query.
	 *
	 * @param string $plugin_dir A reference to the root of the plugin's directory.
	 */
	public function __construct( $plugin_dir ) {
		$this->messenger = new Post_Messenger( $plugin_dir );
	}

	/**
	 * If there are posts to display, renders them in the metabox. Otherwise, displays
	 * a note that there are no posts to display.
	 */
	public function display() {
		$this->messenger->get_message();
	}
}

06-bootstrap.php

<?php

namespace McFarlin\TRP;
use McFarlin\TRP\Display\Meta_Box;

include 'Display/class-meta-box.php';
include 'Display/class-meta-box-display.php';
include 'Utility/class-post-messenger.php';
include 'Utility/class-post-query.php';

add_action( 'add_meta_boxes', __NAMESPACE__ . '\\trp_start' );
/**
 * Starts the plugin.
 */
function trp_start() {

	$meta_box = new Meta_Box( dirname( __FILE__ ) );
	$meta_box->init();
}