the php object option returns a string, not a real php object

Hello,

I notice that when I select php object output, I only get a string, not a real php object, so I cannot access its atomic elements.

Any suggestions, why this is?

$data = whois_get_whois("www.hgf.com");

// these wont work!
print_r ($data->regrinfo->domain);
print('<br>');
print_r ($data["regrinfo"]["domain"]);