pattern-interface-class.php

<?php

/** Do not allow direct access */
defined( 'NDA' ) || exit('Access Denied.');

/**
 * Interface
 *
 * This file attempts to implement formatting and documentation standards
 * so that it can be used with a higher degree of confidence as a template.
 * This specific file interfaces with WordPress by _decoupling_ using an interface.
 * This is important so that the ideas and the code contained herein can be used in
 * frameworks _other_ than WordPress. This is the goal. This is the hope.
 *
 * Note that we do not use WordPress specific calls _except for_ in the class(???).
 *
 * Do we also need an abstract class, or does the interface provide that function.
 *
 * It took a substantial amount of work already just to achieve this level of commonality
 * between the examples given online, the need to follow documation standards and the
 * need to use tabs instead of spaces. When copying code from online, it appears that spaces
 * are used. When this is done, the editor assumes spaces. Thus the indenting may need to be
 * removed, then the text may need to be copied to a new file and the indentation redone, using
 * tabs instead of spaces. This is done to increase interoperability between clients.
 *
 * Note also that UTF-8 is used and line endings may need to be cleared up. Do not close the
 * file with ?>. Open the file with <?php, not <?.
 *
 * @link https://carlalexander.ca/dependency-inversion-principle-wordpress/
 * @see https://en.wikipedia.org/wiki/Dependency_inversion_principle
 */

/**
 * EC01 Options Interface
 */
interface EC01_OptionsInterface
{

	/**
	* Gets the option for the given name. Returns the default value if
	* the value does not exist.
	*
	* @param string $name
	* @param mixed  $default
	*
	* @return mixed
	*/
	public function get($name, $default = null);

	/**
	* Sets an option.
	*
	* @param string $name
	* @param mixed  $value
	*/
	public function set($name, $value);
}

/**
 * EC01 Admin Page Class
 */
class EC01_AdminPage
{
	/**
	* EC01 options
	*
	* @var EC01_OptionsInterface
	*/
	private $options;

	/**
	* Constructor.
	*/
	public function __construct(EC01_OptionsInterface $options)
	{
	$this->options = $options;
	}

	// ...
}

/**
 * EC01 Plugin Class
 *
 * @uses AdminPageInterface
 * @uses OptionsInterface
 * @uses AdminPage
 * @uses OptionsPage
 */
class EC01_Plugin
{
	/**
	* EC01 admin page
	*
	* @var EC01_AdminPageInterface
	*/
	private $admin_page;

	/**
	* Constructor.
	*/
	public function __construct(EC01_AdminPageInterface $admin_page)
	{
		$this->admin_page = $admin_page;
	}

	/**
	* Loads the plugin into WordPress.
	*/
	public function load()
	{
		$this->admin_page->register();
	}
	//...
}
$myplugin = new EC01_Plugin();
add_action('wp_loaded', array($myplugin, 'load'));

/**
 * EC01 Admin Page Interface
 */
interface EC01_AdminPageInterface
{
	/**
	* Register the admin page with WordPress when WordPress loads.
	*/
	public function register();

	//...
}

/**
* EC01 Admin Page Class
*
* Implements EC01 Admin Page Interface
*/
class EC01_AdminPage implements EC01_AdminPageInterface
{

	/**
	* EC01 options
	*
	* @var EC01_OptionsInterface
	*/
	private $options;

	/**
	* Constructor.
	*/
	public function __construct(EC01_OptionsInterface $options)
	{
		$this->options = $options;
	}

	/**
	* Register the admin page with WordPress when WordPress loads.
	*/
	public function register()
	{
		add_menu_page('EC01 Admin Page', 'EC01 Admin Page', 'edit_posts', 'ec01_admin_page', array($this, 'display_page'));
		add_action('admin_menu', array($this, 'add_page'));
	}

	/**
	* Add admin page to WordPress admin menu.
	*/
	public function add_page()
	{
		add_menu_page('EC01 Admin Page', 'EC01 Admin Page', 'edit_posts', 'ec01_admin_page', array($this, 'display_page'));
	}

	/**
	* Display plugin admin page.
	*/
	public function display_page()
	{
		// ...
	}
}