不懂 PHP，看了半天，还是语法不明白，所以来咱 ruby 问问，希望有先行者指点一二。代码如下 这是个打开网站首页调用的代码

<?php
$SCRIPT_START_TIME  = microtime(TRUE);
chdir(dirname(__FILE__));

require_once('./helpers/func_main.php');
require_once('./conf_system.php');

session_start();

//$httpsqs = new httpsqs_client("127.0.0.1", 1218, "q1w2e3r4t5y6", "utf-8");

$cache  = new cache();

$db1        = new mysql($C->DB_HOST, $C->DB_USER, $C->DB_PASS, $C->DB_NAME);
if( ! $C->INSTALLED ) {
    exit;
}

$network    = new network();
$network->LOAD();

$hcadmin=new hcadmin();
$hcadmin->LOAD();

$user       = new user();
$user->LOAD();

ob_start('ob_gzhandler', 6);

$page       = new page();
$page->LOAD();

?>

其中

$db1        = new mysql($C->DB_HOST, $C->DB_USER, $C->DB_PASS, $C->DB_NAME);

这句应该是链接数据库了，参数明白代的意思。但这个$C ->DBHOST，是个什么表达方法？什么意思了？是有定义了一个全局的变量 C，然后赋值 DB-HOST，再作为参数？ 在同目录下的 conf_main.php 文件发现如下

<?php

// Site Address Here:
//

$C->DOMAIN      = $_SERVER['HTTP_HOST'];
$C->SITE_URL        = 'http://' . $_SERVER['HTTP_HOST'] .'/';
if( substr($_SERVER['HTTP_HOST'], 0, 2) == 'm.' || substr($_SERVER['HTTP_HOST'], 0, 4) == 'wap.') {
    $C->DOMAIN      = $_SERVER['HTTP_HOST'];
    $C->SITE_URL    = 'http://' . $_SERVER['HTTP_HOST'] . "/";
}
//
//echo $C->DOMAIN;exit;
// Random identifier for this installation on this server
//
$C->RNDKEY  = '502e6';
//

// MySQL SETTINGS
//
//$C->DB_HOST   = '101.226.179.210 ';
//$C->DB_USER   = 'sq_s520426db0';
//$C->DB_PASS   = 'tiapq666';
//$C->DB_NAME   = 'sq_s520426db0';
$C->DB_HOST = 'localhost';
$C->DB_USER = 's520426db0';
$C->DB_PASS = 'tiapq666';
$C->DB_NAME = 's520426db0';

$C->DB_MYEXT = 'mysql'; // 'mysqli' or 'mysql'
//

// CACHE SETTINGS
//
$C->CACHE_MECHANISM = 'filesystem'; // 'apc' or 'memcached' or 'mysqlheap' or 'filesystem'
$C->CACHE_EXPIRE        = 3600;
$C->CACHE_KEYS_PREFIX   = '502e6';

// If 'memcached':
$C->CACHE_MEMCACHE_HOST = '192.168.0.2';
$C->CACHE_MEMCACHE_PORT = '11200';

// If 'filesystem':
$C->CACHE_FILESYSTEM_PATH   = $C->INCPATH.'cache/';
//

// IMAGE MANIPULATION SETTINGS
//
$C->IMAGE_MANIPULATION  = 'gd'; // 'imagemagick_cli' or 'gd'

// if 'imagemagick_cli' - /path/to/convert
$C->IM_CONVERT  = 'convert';
//

// DEFAULT LANGUAGE
//
$C->LANGUAGE    = 'en';
//

// USERS ACCOUNTS SETTINGS
//
// if urls are user.site.com or site.com/user
// this setting is still beta and it is not working properly
$C->USERS_ARE_SUBDOMAINS    = FALSE;
//

// RPC PING SETTINGS
//
$C->RPC_PINGS_ON        = TRUE;
$C->RPC_PINGS_SERVERS   = array('http://rpc.pingomatic.com');
//

// TWITTER & FACEBOOK CONNECT SETTINGS
//
// To activate Facebook Connect, check out the README.txt file
$C->FACEBOOK_API_KEY        = '';

// To activate Twitter OAuth login, check out the README.txt file
$C->TWITTER_CONSUMER_KEY    = '';
$C->TWITTER_CONSUMER_SECRET = '';

// Bit.ly Integration - used for sharing posts to twitter
$C->BITLY_LOGIN         = 'blogtronixmicro';
$C->BITLY_API_KEY           = 'R_ffd756f66a4f5082e37989f1bc3301a6';

// For inviting Yahoo contacts. Check out the README.txt file
$C->YAHOO_CONSUMER_KEY      = '';
$C->YAHOO_CONSUMER_SECRET   = '';
//

// FOOTER "Powered by Blogtronix" BACKLINK
//
// The License requires you to keep this backlink. To remove it, visit this page
// and follow the instructions: http://sharetronix.com/sharetronix/linkremoval
// Otherwise you are not allowed to modify this variable or remove the link.
$C->FOOTER_REMOVE_BACKLINK  = FALSE;
//

// IF YOUR SERVER SUPPORTS CRONJOBS, READ THE FILE ./system/cronjobs/readme.txt
//
$C->CRONJOB_IS_INSTALLED    = FALSE;
//

// DO NOT REMOVE THIS
//
$C->INSTALLED   = TRUE;
$C->VERSION     = '1.5.4';
$C->DEBUG_USERS     = array();
//
?>

似乎这应该是配置文件，但还是不明白$C->DB_HOST 的写法是要做什么，我猜测是可以全局引用$C?