abstract class alias

<?PHP
    NAMESPACE ILLI\Std\Spl;

    if(class_exists('root\foo')){ class_alias('root\foo', 'ILLI\Std\Spl\foo'); }
    else{ class foo{ } }

    CLASS Test EXTENDS foo{ }

<?PHP
    NAMESPACE root;

    //class foo { public function __construct() { var_dump(__CLASS__); } }

    $e = new \ILLI\Std\Spl\Test;
    $f = 'ILLI\Std\Spl\foo';
    var_dump($e instanceOf $f);