public function __construct($extra_config = array()) { parent::__construct(); if (!empty($extra_config) && is_array($extra_config)) { $merged_configuration = $extra_config + $this->configuration; if (isset($extra_config['classes']) && isset($this->configuration['classes'])) { $merged_configuration['classes'] = $extra_config['classes'] + $this->configuration['classes']; } $this->configuration = $merged_configuration; } }