Loading Classes

Kohana supports the PSR-0 autoloading specification as of version 3.3. This allows you to take advantage of PHP autoloading, removing the need to call include or require before using a class. When you use a class Kohana will find and include the class file for you. For instance, when you want to use the Cookie::set method, you simply call:

Cookie::set('mycookie', 'any string value');

Or to load an Encrypt instance, just call Encrypt::instance:

$encrypt = Encrypt::instance();

Classes are loaded via the Kohana::auto_load method, which makes a simple conversion from class name to file name:

1. Classes are placed in the classes/ directory of the filesystem
2. Any underscore characters in the class name are converted to slashes
3. The filename must match the case of the class

When calling a class that has not been loaded (eg: Session_Cookie), Kohana will search the filesystem using Kohana::find_file for a file named classes/Session/Cookie.php.

If your classes do not follow this convention, they cannot be autoloaded by Kohana. You will have to manually included your files, or add your own autoload function.

Custom Autoloaders

Kohana's default autoloader is enabled in application/bootstrap.php using spl_autoload_register:

spl_autoload_register(array('Kohana', 'auto_load'));

This allows Kohana::auto_load to attempt to find and include any class that does not yet exist when the class is first used as long as it follows the PSR-0 specification. If you wish to support the previous Kohana filename convention (using lowercase filesnames), an additional autoloader is provided by Kohana:

spl_autoload_register(array('Kohana', 'auto_load_lowercase'));

Example: Zend

You can easily gain access to other libraries if they include an autoloader. For example, here is how to enable Zend's autoloader so you can use Zend libraries in your Kohana application.

Download and install the Zend Framework files

• Download the latest Zend Framework files.
• Create a vendor directory at application/vendor. This keeps third party software separate from your application classes.
• Move the decompressed Zend folder containing Zend Framework to application/vendor/Zend.

Include Zend's Autoloader in your bootstrap

Somewhere in application/bootstrap.php, copy the following code:

/**
 * Enable Zend Framework autoloading
 */
if ($path = Kohana::find_file('vendor', 'Zend/Loader'))
{
    ini_set('include_path',
    ini_get('include_path').PATH_SEPARATOR.dirname(dirname($path)));

    require_once 'Zend/Loader/Autoloader.php';
    Zend_Loader_Autoloader::getInstance();
}

Usage example

You can now autoload any Zend Framework classes from inside your Kohana application.

if ($validate($this->request->post()))
{
    $mailer = new Zend_Mail;

    $mailer->setBodyHtml($view)
        ->setFrom(Kohana::$config->load('site')->email_from)
        ->addTo($email)
        ->setSubject($message)
        ->send();
}