Initializing all the classes ?? Is this good ?

Question

Hello, I am a PHP beginner. I have developed a social networking website similar to Orkut in PHP.

The basic program flow of my website is redirect everything to index.php

The index.php determines the $_SERVER['REQUEST_URI'] and does what needs to be done and render the output.

I initiaze all the classes at the top of index.php I want to know if it is a good practice to do this or not.

The index.php starts like this :-

// all the configuration files
require_once ("siteconfig.php");

// include library files / classes
require_once "lib/auth.php";
require_once "lib/album.php";
require_once "lib/db.php";
require_once "lib/form.php";
require_once "lib/inbox.php";
require_once "lib/social.php";
require_once "lib/profile.php";
require_once "lib/user.php";
require_once "lib/settings.php";
require_once "lib/validate.php";
require_once "lib/logs.php";
require_once "lib/sms.php";



// initialize all the classes
$db = new db($dbuser, $dbpass, $dbname, $dbhost);
$validate = new validate();
$auth = new auth();
$user = new user();
$profile = new profile();
$social = new social();
$settings = new settings();
$usersearch = new usersearch();
$album = new album();
$logs = new logs();
$liveupdates = new liveupdates();
$sms = new sms();

Answer 1

Not really. Initialize only what you need. Use autoloading to load on request what you need. Also take a look at Autoloader method from Zend_Loader.

Answer 2

A method I recently learned this year was using an spl autoloader to basically handle any invocation with the new keyword to determine where to actually grab and include a class, I believe this is an example of the lazy loading design pattern.

The tutorial on phpro.org is the one I used to learn how to use it.

However you may need to refactor some of your code if you were to implement this method, might be a good example to paste a snippet of code to see how it interacts with one of your class variable instances.

Answer 3

Initializing all objects from the start is obviously a bad idea. Less obvious is that using "new" in your "main" code is not a brilliant thought either. Use a "loader" that provides you with objects (not classes) you need and avoid "new" outside of the loader.

 // WRONG

 class MainController 
 {
          function action_send_sms() {
              require 'lib/sms.php'; // or use autoload
              $sms = new MySmsClass();
              $sms->send(....)


 // RIGHT

 class Loader
 {
        function sms_object() {
              require 'lib/sms.php'; // or use autoload
              return new MySmsClass();
        }
  ....

 class MainController 
 {
          function action_send_sms() {
              $sms = $this->loader->sms_object();
              $sms->send(....)

// edit: why we would need this?

Imagine you have a number methods in your Controller that use the Sms object. If you use "new" and an explicit class name (the "wrong" approach above), 1) you must provide initialization data (e.g. sms gateway address) for the object in each method, 2) you have to edit your Controller code in case class name or constructor signature changes and 3) your cannot temporary replace Sms object dependent on a condition (e.g. "DummySms" for testing on your local machine).

With Loader class all issues are no problem, because you write all object initialization code exactly once.

(More precisely this pattern is called ServiceLocator, see http://martinfowler.com/articles/injection.html for more details).