Accessing a global array inside class constructor - php

Question

My aim is to retrieve some data from a global array which is defined in another PHP file. My code is running inside database.php file and the array I want to use is inside config.php file. I understand that accessing a global array inside class is not a good idea, but I want to do it so because of some reasons.
My code is as below:
config.php
$CONFIG = array();
// ...
$CONFIG["DATABASE"] = array();
$CONFIG["DATABASE"]["USERNAME"] = "user";
$CONFIG["DATABASE"]["PASSWORD"] = "pass";
$CONFIG["DATABASE"]["HOSTNAME"] = "127.0.0.1";
$CONFIG["DATABASE"]["DATABASE"] = "my_db";
// ...
database.php
require('config.php');
class Database
{
protected $m_Link;
private $m_User;
private $m_Pass;
private $m_Host;
private $m_Data;
private $m_bConnected;
public function __construct()
{
global $CONFIG;
$this->m_User = $CONFIG["DATABASE"]["USERNAME"];
$this->m_Pass = $CONFIG["DATABASE"]["PASSWORD"];
$this->m_Host = $CONFIG["DATABASE"]["HOSTNAME"];
$this->m_Data = $CONFIG["DATABASE"]["DATABASE"];
$this->m_bConnected = false;
$this->Connect();
}
// ...
};
There is no error given (except for the failed database connection notification).
I can't access to the array elements. For instance $CONFIG["DATABASE"]["USERNAME"] returns an empty value even though it was initialized with "user" string in the config.php.
How should I modify my code so that it can this global array can be accessible inside the class constructor?
(Note: PHP version is 5.3.0)

Answer 1

Your code looks right, so I think you should just debug it. Try to output $CONFIG before creating instance of Database class, $CONFIG may be redefined/changed somewhere in your code. And don't just check one value in array - output whole array with var_dump/print_r.

Answer 2

Instead of
$CONFIG = array();
use
$GLOBALS['CONFIG'] = array();

Answer 3

I think some how global is not working in __construct(). I am not sure if it is a bug or it is designed as it is.
For code
<?php
class Test {
public $value;
function __construct() {
global $value;
$value = "I am a test.";
}
}
$test = new Test();
echo $test->value;
You will see nothing when above php runs.
However, if you do not use global, but use $this->value, everything works fine.
<?php
class Test {
public $value;
function __construct() {
$this->value = "I am a test.";
}
}
$test = new Test();
echo $test->value;
If you insist to get a reason. I think maybe __construct() is design to initialize the properties. Some code like $this->value = $value is using a lot in __construct(). So maybe the php designer thinks it is not good practice to use global in __construct(). However. I can not find a word mentioned it in php manual after all.