Cant use the class object with other class - php

Question

I had 2 Class in PHP That i want to use with each other, but the Class in 2 different PHP Script like clothing_product.php and database.php. It look like this Below:
database.php:
require_once('config.php');
class MySqlDatabase
{
private $connection;
private $last_query;
private $magic_quotes_active;
private $real_escape_string_exist;
function __construct(){
$this->open_connection();
$this->magic_quotes_active = get_magic_quotes_gpc();
$this->real_escape_string_exist = function_exists("mysql_real_escape_string");
}
private function open_connection()
{
$this->connection = mysql_connect(DB_SERVER,DB_USER,DB_PASS);
if (!$this->connection){
die("Connection failed!". mysql_error());
}
else{
$db_select = mysql_select_db(DB_NAME);
if(!$db_select){
die("Select database failed". mysql_error());
}
}
}
public function query($sql){
$this->last_query = $sql;
$result = mysql_query($sql,$this->connection);
$this->confirm_query($result);
return $result;
}
public function confirm_query($result){
if(!$result){
$output = "Database query failed: " . mysql_error()."<br /><br />";
$output.= "Last query that fail is:" . $this->last_query;
die($output);
}
}
private function escape_value($value) {
if ($this->real_escape_string_exist) {
if($this->magic_quotes_active) {$value = stripslashes($value);}
$value = mysql_real_escape_string($value);
}
else {
if (!$this->magic_quotes_active) {$value = addslashes($value);}
}
return $value;
}
public function fect_array($result){
return mysql_fetch_array($result);
}
public function num_rows($result){
return mysql_num_rows($result);
}
public function last_id(){
return mysql_insert_id($this->connection);
}
public function affected_rows(){
return mysql_affected_rows($this->connection);
}
public function close_connection(){
if(isset($this->connection)){
mysql_close($this->connection);
unset($this->connection);
}
}
}
//$db = new MySqlDatabase();
clothing_product.php:
include('../database.php');
class Clothing_Product {
public $db = new MySqlDatabase();
public static function test(){
echo "Static call successfull";
return "Static call successfull";
}
}
The problem is when i try to USE 'Public $db = new MySqlDatabase();' in class clothing_product i get Error. I think the problem is maybe i got a wrong call. Please help me cuz m a noob thnk.

Answer 1

You can't initialize member variables to anything that is not static, and you're trying to create an object here:
public $db = new MySqlDatabase();
From the manual:
This declaration may include an initialization, but this
initialization must be a constant value--that is, it must be able to
be evaluated at compile time and must not depend on run-time
information in order to be evaluated.
The workaround is to set your variable in the constructor:
public $db;
public function __construct() {
$this->db = new MySqlDatabase();
}