PHP Singleton sample

gistfile1.php

<?php

class Singleton
{

  /** @var Singleton $_instance */
  private static $_instance = null;

  /**
   * Returns a single instance of Singleton
   * 
   * @returns Singleton
   */
  public static function getIntance()
  {
    if(is_null(self::$_instance)){
      self::$_instance = new self;
    }
    
    return self::$_instance;
  }

  /** Locking for singleton */
  private __construct(){}
  private __clone(){}
  private __wakeup(){}

  /**
   * Just a test function
   */
  public function test(){
    echo 'Hello world!';
  }

}

Singleton::getInstance()->test();