- var_dump: documentation ( source)
<?php
interface IX {}
class X implements IX {}
class Y {}
function foo(IX $x, $y) {}
$rf = new \ReflectionFunction('foo');
$rp = $rf->getParameters()[0];
$x = new X;
var_dump($rp->getType(), $rp->getClass()->isInstance(0), $rf->getParameters()[1]->getClass());