<?php include_once __DIR__ . "/../vendor/autoload.php"; use useful\traits\Singleton; class MyClass { use Singleton; public $hash; function __construct() { $this->hash = md5(rand()); } } class MyClass2 extends MyClass { use Singleton; // note: without defining, it will use existent instance of class MyClass public function getById() { } } echo MyClass::getInstance()->hash . PHP_EOL; echo MyClass2::getInstance()->hash . PHP_EOL;