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 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.
Prior to PHP 8.0.0, it was possible to use __autoload() to autoload classes and interfaces. However, it is a less flexible alternative to spl_autoload_register() and __autoload() is deprecated as of PHP 7.2.0, and removed as of PHP 8.0.0.
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 ($class_name) {
include $class_name . '.php';
});
$obj = new MyClass1();
$obj2 = new MyClass2();
?>
Example #2 Autoload other example
This example attempts to load the interface ITest.
<?php
spl_autoload_register(function ($name) {
var_dump($name);
});
class Foo implements ITest {
}
/*
string(5) "ITest"
Fatal error: Interface 'ITest' not found in ...
*/
?>
Example #3 Autoloading with exception handling
This example throws an exception and demonstrates the try/catch block.
<?php
spl_autoload_register(function ($name) {
echo "Want to load $name.\n";
throw new Exception("Unable to load $name.");
});
try {
$obj = new NonLoadableClass();
} catch (Exception $e) {
echo $e->getMessage(), "\n";
}
?>
The above example will output:
Want to load NonLoadableClass. Unable to load NonLoadableClass.
Example #4 Autoloading with exception handling - Missing custom exception
This example throws an exception for a non-loadable, custom exception.
<?php
spl_autoload_register(function ($name) {
echo "Want to load $name.\n";
throw new MissingException("Unable to load $name.");
});
try {
$obj = new NonLoadableClass();
} catch (Exception $e) {
echo $e->getMessage(), "\n";
}
?>
The above example will output:
Want to load NonLoadableClass. Want to load MissingException. Fatal error: Class 'MissingException' not found in testMissingException.php on line 4