In PHP 5, this is no longer necessary. You may define an __autoload function which is automatically called in case you are trying to use a class/interface which hasn’t been defined yet.
This is how it works in action. We will create two classes. So create Image.php file and paste this in:
[sourcecode language="php"]
<?php
class Image {
function __construct() {
echo 'Class Image loaded successfully <br />';
}
}
?>
[/sourcecode]
Now create Test.php file and paste this in:
[sourcecode language="php"]
<?php
class Test {
function __construct() {
echo 'Class Test working <br />';
}
}
?>
[/sourcecode]
<?php
class Test {
function __construct() {
echo 'Class Test working <br />';
}
}
?>
[/sourcecode]
Basically, we created 2 simple classes with constructors which echo some text out. Now, create a file index.php and paste this in:
[sourcecode language="php"]
<?php
function __autoload($class_name) {
require_once $class_name . '.php';
}
$a = new Test();
$b = new Image();
?>
[/sourcecode]
<?php
function __autoload($class_name) {
require_once $class_name . '.php';
}
$a = new Test();
$b = new Image();
?>
[/sourcecode]
When you run index.php in browser, everything is working fine (assuming all 3 files are in the same folder). Maybe you don’t see a point, but imagine that you have 10 or more classes and have to write require_once as many times.
I will show you how to properly throw exception if you are using PHP 5.3 and above. Chane your index.php to look like this:
[sourcecode language="php"]
<?php
function __autoload($class_name) {
if(file_exists($class_name . '.php')) {
require_once($class_name . '.php');
} else {
throw new Exception("Unable to load $class_name.");
}
}
try {
$a = new Test();
$b = new Image();
} catch (Exception $e) {
echo $e->getMessage(), "\n";
}
?>
[/sourcecode]
<?php
function __autoload($class_name) {
if(file_exists($class_name . '.php')) {
require_once($class_name . '.php');
} else {
throw new Exception("Unable to load $class_name.");
}
}
try {
$a = new Test();
$b = new Image();
} catch (Exception $e) {
echo $e->getMessage(), "\n";
}
?>
[/sourcecode]
Now, it checks if file exists and throws a proper Exception if it doesn’t.
That’s it. A handy functionality to spare some typing.
