While any valid PHP callback may be registered with spl_autoload_register()
, Zend Framework autoloaders often provide more flexibility by being stateful and allowing configuration. To provide a common interface, Zend Framework provides the SplAutoloader
interface.
Objects implementing this interface provide a standard mechanism for configuration, a method that may be invoked to attempt to load a class, and a method for registering with the SPL autoloading mechanism.
To create your own autoloading mechanism, simply create a class implementing the SplAutoloader
interface (you may review the methods defined in the Methods section <zend.loader.spl-autoloader.methods>
). As a simple example, consider the following autoloader, which will look for a class file named after the class within a list of registered directories.
namespace Custom;
use Zend\Loader\SplAutoloader;
class ModifiedIncludePathAutoloader implements SplAutoloader
{
protected $paths = array();
public function __construct($options = null)
{
if (null !== $options) {
$this->setOptions($options);
}
}
public function setOptions($options)
{
if (!is_array($options) && !($options instanceof \Traversable)) {
throw new \InvalidArgumentException();
}
foreach ($options as $path) {
if (!in_array($path, $this->paths)) {
$this->paths[] = $path;
}
}
return $this;
}
public function autoload($classname)
{
$filename = $classname . '.php';
foreach ($this->paths as $path) {
$test = $path . DIRECTORY_SEPARATOR . $filename;
if (file_exists($test)) {
return include($test);
}
}
return false;
}
public function register()
{
spl_autoload_register(array($this, 'autoload'));
}
}
To use this ModifiedIncludePathAutoloader
from the previous example:
$options = array(
'/path/one',
'/path/two'
);
$autoloader = new Custom\ModifiedIncludePathAutoloader($options);
$autoloader->register();
This component defines no configuration options, as it is an interface.
- __construct
Initialize and configure an autoloader
__construct($options = null)
Constructor Autoloader constructors should optionally receive configuration options. Typically, if received, these will be passed to the
setOptions()
method to process.
- setOptions
Configure the autoloader state
setOptions($options)
setOptions() Used to configure the autoloader. Typically, it should expect either an array or a
Traversable
object, though validation of the options is left to implementation. Additionally, it is recommended that the method return the autoloader instance in order to implement a fluent interface.
- autoload
Attempt to resolve a class name to the file defining it
autoload($classname)
autoload() This method should be used to resolve a class name to the file defining it. When a positive match is found, return the class name; otherwise, return a boolean false.
- register
Register the autoloader with the SPL autoloader
register()
register() Should be used to register the autoloader instance with
spl_autoload_register()
. Invariably, the method should look like the following:public function register() { spl_autoload_register(array($this, 'autoload')); }
Please see the Quick Start <zend.loader.spl-autoloader.quick-start>
for a complete example.