Config class with dot notation support.

Config.php

<?php

/**
 * $configs = array(
 *      'app' => array(
 *          'tmp_dir' => '/tmp',
 *          'db' => array(
 *              'database' => 'abc
 *          )
 *      )
 * );
 * $config = new Config($configs);
 * 
 * echo $config->get('app.db.database'); // abc
 * 
 * $config->set('app.tmp_dir', '/usr/tmp');
 * echo $config->get('app.tmp_dir'); // /usr/tmp
 * 
 * var_dump($config->get('app')) // object..
 */
class Config
{
    /**
     * @var array
     */
    protected $data;

    /**
     * @param array $data
     */
    public function __construct(array $data = array())
    {
        $this->data = json_decode(json_encode($data));
    }

    /**
     * @param $key
     * @param null $default
     * @return mixed
     */
    public function get($key, $default = null)
    {
        $value = &$this->data;
        foreach (explode('.', $key) as $step) {
            $value = &$value->{$step};
        }

        if ($value === null) {
            return $default;
        }

        return $value;
    }

    /**
     * @param $key
     * @param $value
     */
    public function set($key, $value)
    {
        $oldValue = &$this->data;
        foreach (explode('.', $key) as $step) {
            $oldValue = &$oldValue->{$step};
        }
        $oldValue = $value;
    }
}