Ensure visibility of a property does not change when unseted

unset.php

<?php

class Foobar
{
    private $foo = 'start';

    public function getFoo()
    {
        return $this->foo;
    }

    public function unsetFoo()
    {
        unset($this->foo);
    }

    public function __get($ppt)
    {
        $this->$ppt = 'magic';

        return $this->$ppt;
    }
}

function display_visibility($object, $attr)
{
    $r = new ReflectionProperty($object, $attr);

    switch (true) {
        case $r->isPublic():
            return 'public';
        case $r->isProtected():
            return 'protected';
        case $r->isPrivate():
            return 'private';
    }
}

$o = new Foobar();
var_dump($o->getFoo());
var_dump(display_visibility($o, 'foo'));
$o->unsetFoo();
var_dump($o->getFoo());
var_dump(display_visibility($o, 'foo'));