public function setExpiration($expiration)
{
$expire_options = $this->_conf->getSection('expire_options');
if (array_key_exists($expiration, $expire_options)) {
$expire = $expire_options[$expiration];
} else {
// using getKey() to ensure a default value is present
$expire = $this->_conf->getKey($this->_conf->getKey('default', 'expire'), 'expire_options');
}
if ($expire > 0) {
$this->_data->meta->expire_date = time() + $expire;
}
}