Functions file pattern for WordPress

functions-pattern.php

<?php

add_action(
  'plugins_loaded',
	array( My_Plugin::get_instance(), 'setup' )
);

class My_Plugin
{
	/**
	 * Instance of this class
	 *
	 * @see get_instance()
	 * @type My_Plugin
	 */
	protected static $instance = null;

	/**
	 * Access to the working instance of this class
	 *
	 * @wp-hook init
	 * @return My_Plugin
	 */
	public static function get_instance()
	{
		null === self::$instance and self::$instance = new self;
		return self::$instance;
	}

	/**
	 * Constructor. Intentionally left empty and public.
	 *
	 * @see setup()
	 */
	public function __construct() {}


	/**
	 * Sets the theme up by adding init actions
	 * @wp-hook plugins_loaded
	 */
	public function setup()
	{
		// Do all initialization, such as adding filters

	}
}