singletontrait.php

См. документацию.

<?php
 
namespace Bitrix\Calendar\Core\Base;
 
trait SingletonTrait
{
    protected static $instance = null;

    public static function getInstance()
    {
        if (static::$instance === null)
        {
            static::$instance = new static();
        }
 
        return static::$instance;
    }
 
 
    protected function __construct(){}

    public function __wakeup()
    {
        throw new BaseException("Trying to wake singleton up");
    }
    protected function __clone(){}
}