PHP read configuration file class instance

<?php 
class Settings { 
 var $_settings = array (); 
 function get($var) { 
 $var = explode ( &#39;.&#39;, $var ); 
 $result = $this->_settings; 
 foreach ( $var as $key ) { 
  if (! isset ( $result [$key] )) { 
  return false; 
  }  
  $result = $result [$key]; 
 }  
 return $result; 
 } 
 function load() { 
 trigger_error ( &#39;Not yet implemented&#39;, E_USER_ERROR ); 
 } 
} 
class Settings_PHP extends Settings { 
 function load($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 == &#39;this&#39;) 
  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 (&#39;spyc.php&#39;); 
 $this->_settings = Spyc::YAMLLoad ( $file ); 
 } 
} 
class Settings_XML extends Settings { 
 function load($file) { 
 if (file_exists ( $file ) == false) { 
  return false; 
 } 
 include (&#39;xmllib.php&#39;); 
 $xml = file_get_contents ( $file ); 
 $data = XML_unserialize ( $xml ); 
 $this->_settings = $data [&#39;settings&#39;]; 
 } 
} 
?>

/** 
* 针对PHP的配置,如有配置文件 
*config.php 
<?php 
$db = array(); 
// Enter your database name here: 
$db[&#39;name&#39;] = &#39;test&#39;; 
// Enter the hostname of your MySQL server: 
$db[&#39;host&#39;] = &#39;localhost&#39;; 
?> 
//具体调用: 
include (&#39;settings.php&#39;); //原始环境假设每个类为单独的一个类名.php文件 
// Load settings (PHP) 
$settings = new Settings_PHP; 
$settings->load(&#39;config.php&#39;); 
echo &#39;PHP: &#39; . $settings->get(&#39;db.host&#39;) . &#39;&#39;; 
* 
*/ 
 读取INI文件,主要用到parser_ini_file函数,该函数返回一个数组,如第二个参数为true时则返回多维数组
/** 
* ini例子:config.ini 
* 
[db] 
name = test 
host = localhost 
//调用例子: 
$settings = new Settings_INI; 
$settings->load(&#39;config.ini&#39;); 
echo &#39;INI: &#39; . $settings->get(&#39;db.host&#39;) . &#39;&#39;; 
*/ 
 读取XML文件,需要用到XML_PARSER，xmllib.php
/** 
* XML例子:config.xml 
<?xml version="1.0" encoding="UTF-8"?> 
<settings> 
<db> 
 <name>test</name> 
 <host>localhost</host> 
</db> 
</settings> 
// Load settings (XML) 
$settings = New Settings_XML; 
$settings->load(&#39;config.xml&#39;); 
echo &#39;XML: &#39; . $settings->get(&#39;db.host&#39;) . &#39;&#39;; 
* 
*/ 
 读取YAML格式文件,使用YAML必须使用到SPYC这个库
/** 
YAML配置例子:config.yaml 
db: 
 name: test 
 host: localhost 
// Load settings (YAML) 
$settings = New Settings_YAML; 
$settings->load(&#39;config.yaml&#39;); 
echo &#39;YAML: &#39; . $settings->get(&#39;db.host&#39;) . &#39;&#39;; 
*/