Joomla\DI\Container

README.md

Joomla\DI\Container

A Dependency Injection container for Joomla. It allows you to pass a key and callback via array syntax to a Joomla\DI\Container instance to help manage the lifesycle of an object.

The callback receives the current instance of the container as it's only (optional) argument. You can reference it to anything, I prefer to use $c (for 'container'). All the public methods of the container are avialable within the callback.

$config = array(
	'mailer.username' => 'foo',
	'mailer.password' => 'bar'
);

$dic = new \Joomla\DI\Container($config);

$dic['mailerTransport'] = function($c)
{
	return new Zend_Mail_Transport_Smtp('smtp.gmail.com', array(
		'auth'     => 'login',
		'username' => $c->getParam('mailer.username'),
		'password' => $c->getParam('mailer.password'),
		'ssl'      => 'ssl',
		'port'     => 465
	));
};

Creating an Application Instance

A very simplistic example that is obviously overkill for this situation. The AbstractWebApplication takes a Joomla\Input\Input dependency in the constructor.

class App extends \Joomla\Application\AbstractWebApplication { /* required methods */ }

$dic = new Joomla\DI\Container;

$dic['input'] = function ()
{
	// Use $_GET data only
	return new \Joomla\Input\Input($_GET);
}

$dic['app'] = function ($c)
{
	return new App($c['input']);
};

$dic['app']->execute();

To Do

• Add more (extended) examples
• Better documentation

Container.php

<?php
/**
 * Potentially Part of the Joomla Framework DI Package
 *
 * @copyright  Copyright (C) 2013 Don Gilbert. All rights reserved.
 * @license    LGPL version 2 or later; see http://www.gnu.org/licenses/old-licenses/lgpl-2.0.html
 */

namespace Joomla\DI;

class Container implements \ArrayAccess
{
	/**
	 * Holds the shared instances.
	 *
	 * @var    array  $instances
	 *
	 * @since  1.0
	 */
	private $instances = array();

	/**
	 * Holds the keys, their callbacks, and whether or not
	 * the item is meant to be a shared resource.
	 *
	 * @var    array  $dataStore
	 *
	 * @since  1.0
	 */
	private $dataStore = array();

	/**
	 * Holds config options accessible within the passed callback.
	 *
	 * @var    array  $config
	 *
	 * @since  1.0
	 */
	public $config = array('default.shared' => true);

	/**
	 * Constructor for the DI Container
	 *
	 * @param  array  $config  Array of configuration parameters.
	 *
	 * @since  1.0
	 */
	public function __construct(array $config = array())
	{
		$this->setConfig($config);
	}

	/**
	 * Method to set the key and callback to the dataStore array.
	 *
	 * @param   string    $key       Name of dataStore key to set.
	 * @param   callable  $callback  Callable function to run when requesting the specified $key.
	 * @param   boolean   $shared    True to create and store a shared instance.
	 *
	 * @return  Joomla\DI\Container  This instance to support chaining.
	 *
	 * @since   1.0
	 */
	public function set($key, $callback, $shared = true)
	{
		if (isset($this->dataStore[$key]))
		{
			throw new \OutOfBoundsException(sprintf('Key %s has already been assigned.', $key));
		}

		if (!is_callable($callback))
		{
			throw new \UnexpectedValueException('Provided value is not a valid callback.');
		}

		$this->dataStore[$key] = array(
			'callback' => $callback,
			'shared' => $shared
		);

		return $this;
	}

	/**
	 * Method to retrieve the results of running the $callback for the specified $key;
	 *
	 * @param   string  $key  Name of the dataStore key to get.
	 *
	 * @return  mixed   Results of running the $callback for the specified $key.
	 *
	 * @since   1.0
	 */
	public function get($key)
	{
		if (!isset($this->dataStore[$key]))
		{
			throw new \InvalidArgumentException(sprintf('Key %s has not been registered with the container.', $key));
		}

		if ($this->dataStore[$key]['shared'])
		{
			if (!isset($this->instances[$key]))
			{
				$this->instances[$key] = $this->dataStore[$key]['callback']($this);
			}

			return $this->instances[$key];
		}

		return $this->dataStore[$key]['callback']($this);
	}

	/**
	 * Method to set an array of config options.
	 *
	 * @param   array  $config  Associative array to merge with the internal config.
	 *
	 * @return  Joomla\DI\Container  This instance to support chaining.
	 *
	 * @since   1.0
	 */
	public function setConfig(array $config)
	{
		$this->config = array_merge($this->config, $config);

		return $this;
	}

	/**
	 * Method to retrieve the entire config array.
	 *
	 * @return  array  The config array for this instance.
	 *
	 * @since   1.0
	 */
	public function getConfig()
	{
		return $this->config;
	}

	/**
	 * Method to set a single config option.
	 *
	 * @param   string  $key    Name of config key.
	 * @param   mixed   $value  Value of config key.
	 *
	 * @return  Joomla\DI\Container  This instance to support chaining.
	 *
	 * @since   1.0
	 */
	public function setParam($key, $value)
	{
		$this->config[$key] = $value;

		return $this;
	}

	/**
	 * Method to retrieve a single configuration parameter.
	 *
	 * @param   string  $key  Name of config key to retrieve.
	 *
	 * @return  mixed  Value of config $key or null if not yet set.
	 *
	 * @since   1.0
	 */
	public function getParam($key)
	{
		return isset($this->config[$key]) ? $this->config[$key] : null;
	}

	/**
	 * Whether an offset exists.
	 *
	 * @param   string  $key  Name of the bindings key to check if exists.
	 *
	 * @return  boolean  True if the specified offset exists.
	 *
	 * @since   1.0
	 */
	public function offsetExists($key)
	{
		return isset($this->dataStore[$key]);
	}

	/**
	 * Offset to retrieve.
	 *
	 * @param   string  $key  Name of the dataStore key to get.
	 *
	 * @return  mixed  Results of running the $callback for the specified $key.
	 *
	 * @since   1.0
	 */
	public function offsetGet($key)
	{
		return $this->get($key);
	}

	/**
	 * Offset to set.
	 *
	 * @param   string    $key       Name of dataStore key to set.
	 * @param   callable  $callback  Callable function to run when requesting $key.
	 *
	 * @return  void
	 *
	 * @since   1.0
	 */
	public function offsetSet($key, $callback)
	{
		$this->set($key, $callback, $this->config['default.shared']);
	}

	/**
	 * Offset to unset.
	 *
	 * @param   string  $key  Offset to unset.
	 *
	 * @return  void
	 *
	 * @since   1.0
	 */
	public function offsetUnset($key)
	{
		unset($this->dataStore[$key]);
	}
}

I like the simplicity a lot.