Symfony sfGuardUserPlugin - check password for any user

How can I check any user's password in Symfony? (not only the logged in user) (I use sfGuardPlugin)

I've tried like this, but doesn't work:

$user = Doctrine::getTable('sfGuardUser')->find(26);
$is_passwor开发者_运维问答d_valid = $user->checkPassword('password');