3v4l.org

run code in 300+ PHP versions simultaneously
<?php class Foo { public function dump(self $baz) { var_dump($baz); } } class Bar extends Foo { } (new Foo)->dump(new Bar); (new Bar)->dump(new Bar); (new Bar)->dump(new Foo);

preferences:
42.98 ms | 402 KiB | 5 Q