Singleton.php

<?php

trait Singleton
{
    protected static $instance;
 
    protected function __construct()
    {
        static::setInstance($this);
    }
 
    final public static function setInstance($instance)
    {
        static::$instance = $instance;
        return static::$instance;
    }
 
    final public static function getInstance()
    {
        return isset(static::$instance)
            ? static::$instance
            : static::$instance = new static;
    }
}