Roles and permissions

Hi there...

As we have an seperate authentication system and we don't want our teachers to change the course Full name, Short name, Course ID number in the "Edit course settings" page, so I have implemented the following code in the /course/edit_form.php to add a isadmin() check

if (isadmin()) {
$mform->setHelpButton('category', array('coursecategory', get_string('category')));
$mform->setDefault('category', $category->id);
$mform->setType('category', PARAM_INT);

$mform->addElement('text','fullname', get_string('fullname'),'maxlength="254" size="50"');
$mform->setHelpButton('fullname', array('coursefullname', get_string('fullname')), true);
$mform->setDefault('fullname', get_string('defaultcoursefullname'));
$mform->addRule('fullname', get_string('missingfullname'), 'required', null, 'client');
$mform->setType('fullname', PARAM_MULTILANG);

$mform->addElement('text','shortname', get_string('shortname'),'maxlength="100" size="20"');
$mform->setHelpButton('shortname', array('courseshortname', get_string('shortname')), true);
$mform->setDefault('shortname', get_string('defaultcourseshortname'));
$mform->addRule('shortname', get_string('missingshortname'), 'required', null, 'client');
$mform->setType('shortname', PARAM_MULTILANG);

$mform->addElement('text','idnumber', get_string('idnumbercourse'),'maxlength="100" size="10"');
$mform->setHelpButton('idnumber', array('courseidnumber', get_string('idnumbercourse')), true);
$mform->setType('idnumber', PARAM_RAW);

} else {
$mform->addElement('text','fullname', get_string('fullname'),'disabled maxlength="254" size="50"');
$mform->setHelpButton('fullname', array('coursefullname', get_string('fullname')), true);
$mform->addElement('text','shortname', get_string('shortname'),'disabled maxlength="100" size="20"');
$mform->setHelpButton('shortname', array('courseshortname', get_string('shortname')), true);
$mform->addElement('text','idnumber', get_string('idnumbercourse'),'disabled maxlength="100" size="10"');
$mform->setHelpButton('idnumber', array('courseidnumber', get_string('idnumbercourse')), true);
}

However I think in moodle 1.9 this is probably not the best way to implement it as we should probably avoid using isadmin(). However I couldn't find a matching "has_capability()" to implmement this. Any suggestion? Thanks!