[WordPress] Tools for Writing Better WordPress Code: Composer

00-sample-plugin.php

<?php
/**
 * The plugin bootstrap file
 *
 * This file is read by WordPress to generate the plugin information in the plugin
 * admin area. This file also includes all of the dependencies used by the plugin,
 * registers the activation and deactivation functions, and defines a function
 * that starts the plugin.
 *
 * @since             0.1.0
 * @package           SamplePlugin
 *
 * @wordpress-plugin
 * Plugin Name:       Sample Plugin
 * Description:       A sample plugin used for a blog post.
 * Version:           0.1.0
 * Author:            Tom McFarlin
 * Author URI:        https://tommcfarlin.com
 * License:           GPL-3.0+
 * License URI:       http://www.gnu.org/licenses/gpl-3.0.txt
 */

namespace SamplePlugin;

use SamplePlugin\Messenger;

// This file called directly.
defined('WPINC') || die;

// Include the autoloader.
require_once __DIR__ . '/vendor/autoload.php';

// Start the machine.
(new Messenger())->start();

01-messenger.php

<?php

namespace SamplePlugin;

class Messenger
{
    /**
     * Subscribers the `adminNotices` function to the admin_notices hook in WordPress.
     */
    public function start()
    {
        add_action('admin_notices', [$this, 'adminNotices']);
    }

    /**
     * Displays the contents of the `message.html` file into the adminitrative notices
     * area on the dashboard whenever the plugin is active.
     */
    public function adminNotices()
    {
        if ('dashboard' !== get_current_screen()->id) {
            return;
        }

        include_once dirname(__FILE__) . '/Admin/Views/message.html';
    }
}

02-message.html

<div class="notice notice-success is-dismissible">
    <p>This is a message from the <strong>Sample Plugin</strong></p>
</div>

03-composer.json

{
    "name": "tommcfarlin/sample-plugin",
    "description": "A sample plugin used for a blog post.",
    "type": "wordpress-plugin",
    "license": "GPL-3.0-or-later",
    "authors": [
      {
        "name": "Tom McFarlin",
        "email": "tom@tommcfarlin.com",
        "homepage": "https://tommcfarlin.com"
      }
    ],
      "autoload": {
        "psr-4": {
          "SamplePlugin\\": "src/"
        }
      }
  }

04-run-composer.txt

$ composer install