ZEND PHP 5 Certification STUDY GUIDE

174 ” Elements of Object-oriented Design
class Configuration_DB {
// ...
}
class Configuration_XML {
// ...
}
$config = Configuration::getStore(Configuration::STORE_XML);
The Registry Pattern
By taking the Singleton pattern a little further, we can implement the Registry pattern.
This allows us to use any object as a Singleton without it being written specifically
that way.
The Registry pattern can be useful, for example, if, for the bulk of your application,
you use the same database connection, but need to connect to an alternate database
to perform a small set of tasks every now and then. If your DB class is implemented
as a Singleton, this is impossible (unless you implement two separate classes, that
is)—but a Registry makes it very easy:
class Registry {
private static $_register;
public static function add(&$item, $name = null)
{
if (is_object($item) && is_null($name)) {
$name = get_class($item);
} elseif (is_null($name)) {
$msg = "You must provide a name for non-objects";
throw new Exception($msg);
}
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)
$name = strtolower($name);
}
self::$_register[$name] = $item;
public static function &get($name)
{
$name = strtolower($name);