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run code in 300+ PHP versions simultaneously
<?php abstract class T { static protected $instanses; final private function __construct(){ } public static function getInstance() { if (!isset(static::$instanses)) { static::$instanses = new static; } return static::$instanses; } } class A extends T { static protected $instanses; } class B extends A { static protected $instanses; } $t = A::getInstance(); var_dump($t); $t1 = B::getInstance(); var_dump($t1); new B(); ?>

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43.04 ms | 402 KiB | 5 Q