PHP class for reading configuration files PHP reads ini, yaml, xml configuration file information

/**
* Function: Read configuration file
* Editor: bbs.it-home.org
* Last modified: 2013/10/11
*/
class Settings {
    var $_settings = array();

    function get($var) {
        $var = explode('.', $var);
        $result = $this->_settings;
        foreach ($var as $key) {
            if (!isset ($result [$key])) {
                return false;
            }
            $result = $result [$key];
        }
        return $result;
    }

    function load() {
        trigger_error('Not yet implemented', E_USER_ERROR);
    }
}

class Settings_PHP extends Settings {
    function load($file) {
        if (file_exists($file) == false) {
            return false;
        }

        // Include file
        include ($file);
        unset ($file);

        // Get declared variables
        $vars = get_defined_vars();

        // Add to settings array
        foreach ($vars as $key => $val) {
            if ($key == 'this')
                continue;
            $this->_settings [$key] = $val;
        }

    }
}

class Settings_INI extends Settings {
    function load($file) {
        if (file_exists($file) == false) {
            return false;
        }
        $this->_settings = parse_ini_file($file, true);
    }
}

class Settings_YAML extends Settings {
    function load($file) {
        if (file_exists($file) == false) {
            return false;
        }

        include ('spyc.php');
        $this->_settings = Spyc::YAMLLoad($file);
    }
}

class Settings_XML extends Settings {
    function load($file) {
        if (file_exists($file) == false) {
            return false;
        }

        include ('xmllib.php');
        $xml = file_get_contents($file);
        $data = XML_unserialize($xml);

        $this->_settings = $data ['settings'];
    }
}
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