1. What are Autoloading Classes?

Many developers writing object-oriented applications create one PHP source file per class definition. One of the biggest annoyances is having to write a long list of needed includes at the beginning of each script (one for each class).

2. How to use Autoload Classes

In PHP 5, this is no longer necessary. The spl_autoload_register() function registers any number of autoloaders, enabling for classes and interfaces to be automatically loaded if they are currently not defined. By registering autoloaders, PHP is given a last chance to load the class or interface before it fails with an error.

Example #1 Autoload example

This example attempts to load the classes MyClass1 and MyClass2 from the files MyClass1.php and MyClass2.php respectively.

	<?php
	spl_autoload_register(function ($name) {
	echo "Want to load $name.\n";
	throw new Exception("Unable to load $name.");
	});
	try {
	$obj = new NonLoadableClass();
	} catch (Exception $e) {
	echo $e->getMessage(), "\n";
	}
	?>

view raw autoload.php hosted with by GitHub

Example #2 Autoload other example

This example attempts to load the interface ITest.

	<?php
	spl_autoload_register(function ($name) {
	echo "Want to load $name.\n";
	throw new Exception("Unable to load $name.");
	});
	try {
	$obj = new NonLoadableClass();
	} catch (Exception $e) {
	echo $e->getMessage(), "\n";
	}
	?>

view raw autoload.php hosted with by GitHub

Example #3 Autoloading with exception handling for 5.3.0+

This example throws an exception and demonstrates the try/catch block.

	<?php
	spl_autoload_register(function ($name) {
	echo "Want to load $name.\n";
	throw new Exception("Unable to load $name.");
	});
	try {
	$obj = new NonLoadableClass();
	} catch (Exception $e) {
	echo $e->getMessage(), "\n";
	}
	?>

view raw autoload.php hosted with by GitHub

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Pradeep K