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Autoloading Classes

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).

The 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. spl_autoload_register

Any class-like construct may be autoloaded the same way. That includes classes, interfaces, traits, and enumerations.

Let op: > Prior to PHP 8.0.0, it was possible to use to autoload classes and interfaces. However, it is a less flexible alternative to and is deprecated as of PHP 7.2.0, and removed as of PHP 8.0.0. __autoload``spl_autoload_register``__autoload

Opmerking: > may be called multiple times in order to register multiple autoloaders. Throwing an exception from an autoload function, however, will interrupt that process and not allow further autoload functions to run. For that reason, throwing exceptions from an autoload function is strongly discouraged. spl_autoload_register

Voorbeeld: Autoload example

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

<?php
spl_autoload_register(function ($class_name) {
    include $class_name . '.php';
});

$obj  = new MyClass1();
$obj2 = new MyClass2(); 
?>

Voorbeeld: Autoload other example

 This example attempts to load the interface .
`ITest`

<?php

spl_autoload_register(function ($name) {
    var_dump($name);
});

class Foo implements ITest {
}

/*
string(5) "ITest"

Fatal error: Interface 'ITest' not found in ...
*/
?>

Voorbeeld: Using Composer's autoloader

 link.composer generates a 
 which is set up to automatically load packages that are being managed
 by Composer. By including this file, those packages can be used without
 any additional work.
`vendor/autoload.php`

<?php
require __DIR__ . '/vendor/autoload.php';

$uuid = Ramsey\Uuid\Uuid::uuid7();

echo "Generated new UUID -> ", $uuid->toString(), "\n";
?>

unserializeunserialize_callback_funcunserialize_max_depthspl_autoload_register``spl_autoload``__autoload

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