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RobotLoader: Class Autoloading

When working with Nette Framework, forget about including every single file using require or include. Nette cares about your comfort and does it itself.

  • get rid of all require
  • only necessary scripts are loaded
  • requires no strict file naming conventions
  • allows more classes in single file

We can load Nette Framework with a single command: require 'Nette/loader.php' (the path may be different of course) and all of its classes will be loaded automatically when you use them for the first time. That not only saves you a lot of writing, but it also accelerates entire application. Why? Simply because only those files that are actually needed are loaded. No unnecessary files get parsed by PHP.

Nette\Loaders\RobotLoader

Nette\Loaders\RobotLoader is a tool that gives you comfort of automated class loading for your entire application including third-party libraries. So we can forget about those famous code blocks:

require_once 'Zend/Pdf/Page.php';
require_once 'Zend/Pdf/Style.php';
require_once 'Zend/Pdf/Color/GrayScale.php';
require_once 'Zend/Pdf/Color/Cmyk.php';
...

Like the Google robot crawls and indexes websites, RobotLoader crawls all PHP scripts and records what classes and interfaces were found in them. These records are then saved in cache and used during all subsequent requests. You just need to specify what directories to index and where to save the cache:

$loader = new Nette\Loaders\RobotLoader;
// Add directories for RobotLoader to index
$loader->addDirectory('app');
$loader->addDirectory('libs');
// And set caching to the 'temp' directory on the disc
$loader->setCacheStorage(new Nette\Caching\Storages\FileStorage('temp'));
$loader->register(); // Run the RobotLoader

And that's all. From now on, you don't need to use require. Great, isn't it?

When RobotLoader encounters duplicate class name during indexing, it throws an exception and informs you about it.

Inside sandbox, where the paths to application and library files are defined in APP_DIR and LIBS_DIR constants, it's possible to use the following in bootstrap.php:

$configurator = new Nette\Config\Configurator;

// Enable RobotLoader - this will load all classes automatically
$configurator->setTempDirectory(__DIR__ . '/../temp');
$configurator->createRobotLoader()
	->addDirectory(APP_DIR)
	->addDirectory(LIBS_DIR)
	->register();

The variable $loader->autoBuild determines whether RobotLoader should reindex the scripts if asked for nonexistent class. This feature is disabled by default on production server.

Therefore, it's necessary to delete the cache when uploading a new version of your application.

If you want RobotLoader to skip some directory, create a file there called netterobots.txt:

Disallow: /Zend

From this point on, the Zend directory will not be indexed.

RobotLoader is extremely comfortable and addictive!