ZEND PHP 5 Certification STUDY GUIDE

Elements of Object-oriented Design ” 175
if (array_key_exists($name, self::$_register)) {
return self::$_register[$name];
} else {
$msg = "’$name’ is not registered.";
throw new Exception($msg);
}
}
public static function exists($name)
{
$name = strtolower($name);
if (array_key_exists($name, self::$_register)) {
return true;
} else {
return false;
}
}
}
$db = new DB();
Registry::add($db);
// Later on
if (Registry::exists(’DB’)) {
$db = Registry::get(’DB’);
} else {
die(’We lost our Database connection somewhere. Bear with us.’);
}
The Model-View-Controller Pattern
Unlike the patterns we have seen this far, Model-View-Controller (MVC) is actually
quite complex. Its goal is that of providing a methodology for separating the business
logic (model) from the display logic (view) and the decisional controls (controller).
In a typical MVC setup, the user initiates an action (even a default one) by calling
the Controller. This, in turn, interfaces with the Model, causing it to perform some
sort of action and, therefore, changing its state. Finally, the View is called, thus causing
the user interface to be refreshed to reflect the changes in the Model and the
action requested of the Controller, and the cycle begins anew.
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)