ClassLoader Component ===================== ClassLoader loads your project classes automatically if they follow some standard PHP conventions. The Universal ClassLoader is able to autoload classes that implement the PSR-0 standard or the PEAR naming convention. First, register the autoloader: ```php require_once __DIR__.'/src/Symfony/Component/ClassLoader/UniversalClassLoader.php'; use Symfony\Component\ClassLoader\UniversalClassLoader; $loader = new UniversalClassLoader(); $loader->register(); ``` Then, register some namespaces with the `registerNamespace()` method: ```php $loader->registerNamespace('Symfony', __DIR__.'/src'); $loader->registerNamespace('Monolog', __DIR__.'/vendor/monolog/src'); ``` The `registerNamespace()` method takes a namespace prefix and a path where to look for the classes as arguments. You can also register a sub-namespaces: ```php $loader->registerNamespace('Doctrine\\Common', __DIR__.'/vendor/doctrine-common/lib'); ``` The order of registration is significant and the first registered namespace takes precedence over later registered one. You can also register more than one path for a given namespace: ```php $loader->registerNamespace('Symfony', array(__DIR__.'/src', __DIR__.'/symfony/src')); ``` Alternatively, you can use the `registerNamespaces()` method to register more than one namespace at once: ```php $loader->registerNamespaces(array( 'Symfony' => array(__DIR__.'/src', __DIR__.'/symfony/src'), 'Doctrine\\Common' => __DIR__.'/vendor/doctrine-common/lib', 'Doctrine' => __DIR__.'/vendor/doctrine/lib', 'Monolog' => __DIR__.'/vendor/monolog/src', )); ``` For better performance, you can use the APC based version of the universal class loader: ```php require_once __DIR__.'/src/Symfony/Component/ClassLoader/UniversalClassLoader.php'; require_once __DIR__.'/src/Symfony/Component/ClassLoader/ApcUniversalClassLoader.php'; use Symfony\Component\ClassLoader\ApcUniversalClassLoader; $loader = new ApcUniversalClassLoader('apc.prefix.'); ``` Furthermore, the component provides tools to aggregate classes into a single file, which is especially useful to improve performance on servers that do not provide byte caches.