Building the Back End: Part 1 - Realtime Web Apps: With HTML5 WebSocket, PHP, and jQuery - page 164

// Tries to initialize the requested view, or else throws a 404 error
try {
$controller = new $class_name($options);
} catch (Exception $e) {
$options[1] = $e->getMessage();
$controller = new Error($options);
}

//-----------------------------------------------------------------------------
// Function declarations
//-----------------------------------------------------------------------------

Using the utility functions, the URI is broken apart and stored in $uri_array . It is then passed to
get_controller_classname() , which stores the controller's class name in $class_name . The remaining URI
components are stored in $options for later use.
Next, $class_name is checked to ensure it isn't empty; if it is, the default class name “Home” is supplied.
Finally, using a try...catch block, a new controller object of the requested type is instantiated, passing the
$options as an argument to the constructor. If anything goes wrong, a new Error object is created to display an
error message.

■ Note You will be building the Error class later in this chapter.

Outputting the View
With the controller loaded, there's nothing left to do but output the markup. In index.php , add the following
bold code:

//-----------------------------------------------------------------------------
// Loads and processes view data
//-----------------------------------------------------------------------------

// Parses the URI
$uri_array = parse_uri();
$class_name = get_controller_classname($uri_array);
$options = $uri_array;

// Sets a default view if nothing is passed in the URI (i.e. on the home page)
if (empty($class_name)) {
$class_name = 'Home';
}

// Tries to initialize the requested view, or else throws a 404 error
try {
$controller = new $class_name($options);
} catch (Exception $e) {
$options[1] = $e->getMessage();
$controller = new Error($options);
}