getMethods()); function __autoload($cls) { if ($cls == "MyClass") { class MyClass {} } } interface I { function f(MyClass $c); } try { $r = new ReflectionClass('I'); foreach ($r->getMethods() as $m) { foreach ($m->getParameters() as $p) { $p->getClass(); var_dump($p); } } } catch (Exception $e) { var_dump($e->getMessage()); }