/**
* Attempts to return a reference to a concrete
* Horde_Kolab_Resource_Getfreebusy instance based on $driver.
*
* It will only create a new instance if no Horde_Kolab_Resource_Getfreebusy
* instance with the same parameters currently exists.
*
* This method must be invoked as:
* <code>$var = Horde_Kolab_Resource_Getfreebusy::singleton();</code>
*
* @param mixed $driver The type of concrete
* Horde_Kolab_Resource_Getfreebusy subclass to
* return.
* @param array $params A hash containing any additional configuration or
* connection parameters a subclass might need.
*
* @return Horde_Token The concrete Horde_Kolab_Resource_Getfreebusy
* reference, or false on error.
*/
public static function singleton($driver = null, $params = array())
{
global $conf;
if (isset($GLOBALS['KOLAB_FILTER_TESTING'])) {
$driver = 'mock';
$params['data'] = $GLOBALS['KOLAB_FILTER_TESTING'];
}
if (empty($driver)) {
if (isset($conf['freebusy']['driver'])) {
$driver = $conf['freebusy']['driver'];
} else {
$driver = 'Kolab';
}
}
ksort($params);
$sig = hash('md5', serialize(array($driver, $params)));
if (!isset(self::$_instances[$sig])) {
self::$_instances[$sig] = Horde_Kolab_Resource_Freebusy::factory($driver, $params);
}
return self::$_instances[$sig];
}
