PHP Singleton Design Pattern with __construct()

SingletonWithConstructor.php

<?php
/**
 * @author    : JIHAD SINNAOUR
 * @package   : VanillePlugin
 * @version   : 0.9.2
 * @copyright : (c) 2018 - 2022 Jihad Sinnaour <[email protected]>
 * @link      : https://jakiboy.github.io/VanillePlugin/
 * @license   : MIT
 */

/**
 * Proof of work: Singleton with constructor
 */
final class Singleton // Restrict inheritance
{
	/**
	 * @access private
	 * @var bool $initialized, Keep instance status in memory
	 */
	private static $initialized = false;

	/**
	 * __construct
	 * @param void
	 */
	public function __construct()
	{
		// Construct only if not already initialized
		if ( !static::$initialized ) {

			// Something here
			// ...

			// Finish initialization
			static::$initialized = true;
		}
	}

	/**
	 * __destruct
	 */
	public function __destruct()
	{
		// Something here
		// ...
	}

	/**
	 * Restrict object clone.
	 */
	public function __clone()
	{
		die(__METHOD__ . ': Clone denied');
	}

	/**
	 * Restrict object unserialize.
	 */
	public function __wakeup()
	{
		die(__METHOD__ . ': Unserialize denied');
	}
	
	/**
	 * Initialize instance.
	 * 
	 * @access public
	 * @param void
	 * @return void
	 */
	public static function init() : void
	{
		// Initialize only if not already initialized
		if ( !static::$initialized ) {
			new static;
		}
	}

	/**
	 * Return instance.
	 * 
	 * @access public
	 * @param void
	 * @return mixed
	 */
	public static function returnInstance() : mixed
	{
		// Return only if not already initialized
		if ( !static::$initialized ) {
			return new static;
		}
	}
}