trait AutoConfigurable {

	/**
	 * Stores configuration information for object instances at time of construction.
	 *
	 * @var array
	 */
	protected $_config = [];

	/**
	 * Default constructor implementation. Initializes class configuration (`$_config`), and
	 * assigns object properties using the `_init()` method, unless otherwise specified by
	 * configuration. See below for details.
	 *
	 * @see lithium\core\AutoConfigurable::$_config
	 * @see lithium\core\AutoConfigurable::_init()
	 * @param array $config The configuration options which will be assigned to the `$_config`
	 *        property. This method accepts one configuration option:
	 *        - `'init'` _boolean_: Controls constructor behavior for calling the `_init()`
	 *          method. If `false`, the method is not called, otherwise it is. Defaults to `true`.
	 * @return void
	 */
	public function __construct(array $config = []) {
		$this->_autoConfig($config, isset($this->_autoConfig) ? $this->_autoConfig : []);
		$this->_autoInit($config);
	}

	/**
	 * Assigns configuration values to object properties.
	 *
	 * For example, given the following:
	 * ```
	 * class Bar {
	 * 	protected $_foo;
	 *
	 * 	public function __construct(array $config = []) {
	 *		$this->_autoConfig($config, ['foo']);
	 * 	}
	 * }
	 *
	 * $instance = new Bar(['foo' => 'baz']);
	 * ```
	 *
	 * The `foo` property would automatically be set to `'baz'`. If `foo` was an array,
	 * `$auto` could be set to `['foo' => 'merge']`, and the config value of `'foo'`
	 * would be merged with the default value of the `foo` property and assigned to it.
	 *
	 * @param array $config
	 * @param array $auto An array of values that should be processed. Each value should have
	 *      a matching protected property (prefixed with `_`) defined in the class. If the
	 *      property is an array, the property name should be the key and the value should
	 *      be `'merge'`.
	 * @return void
	 */
	protected function _autoConfig(array $config, array $auto) {
		$this->_config = $config;

		foreach ($auto as $key => $flag) {
			if (!isset($config[$key]) && !isset($config[$flag])) {
				continue;
			}
			if ($flag === 'merge') {
				$this->{"_{$key}"} = $config[$key] + $this->{"_{$key}"};
			} else {
				$this->{"_$flag"} = $config[$flag];
			}
		}
	}

	protected function _autoInit($config) {
		if (!isset($config[AUTO_INIT_CLASS]) || $config[AUTO_INIT_CLASS] !== false) {
			$this->_init();
		}
	}

	/**
	 * Empty `_init()` method, intended to be overridden if needed.
	 *
	 * @return void
	 */
	protected function _init() {}
}