/**
* Setter for the Registrationgroup Part of the ISBN Number
*
* @param string $group Registrationsgroup to set
*
* @return void
*
* @throws ISBN_Exception in case it fails
*/
function _setGroup($group)
{
if (is_string($group) == false) {
return new ISBN_Exception('Wrong Vartype');
}
$l = strlen($group);
if ($l < 1 || $l > 5) {
return new ISBN_Exception('Wrong Group Length (' . $l . ')');
}
$testbody = substr($group . '000000000', 0, 9);
$testgroup = ISBN::_extractGroup($testbody);
if ($testgroup === false) {
return new ISBN_Exception('Invalid Group');
}
if ($testgroup != $group) {
return new ISBN_Exception('Invalid Group');
}
$this->isbn_group = $group;
}