protected static function _class($config, $paths = []) {
		if (!$name = $config['adapter']) {
			$self = get_called_class();
			throw new ConfigException("No adapter set for configuration in class `{$self}`.");
		}
		if (!$class = static::_locate($paths, $name)) {
			$self = get_called_class();
			throw new ConfigException("Could not find adapter `{$name}` in class `{$self}`.");
		}
		return $class;
	}