Can't call an object method. PHP reports variable undefined - php

Question

This is the weirdest bug! It is probably something silly, but I have no idea how to fix it. If anyone could help, I would be most grateful! I have three files, one is called items.php, another is called tableFunctions.php, and the third is called mysql.php. I use two global objects called 'mysql' and 'tableFunctions'. They are stored in the files 'mysql.php', and
'tableFunctions.php', respectively. In each file, I create an instance of its object, assigning it to the global variable $_mysql, or $_table. like this:
In the file mysql.php:
global $_mysql;
$_mysql = new mysql();
In the file tableFunctions.php:
global $_table;
$_table = new tableFunctions();
Here's how it is supposed to work:
The items.php file includes the tableFunctions.php file...
Which in turn, needs the mysql.php file, so it includes it too.
In the items.php file, I call the method getTable(), which is contained in the object tableFunctions.(and in the variable $_table.) Like this:
$t = $_table->getTable('items');
The getTable function calls the method, arrayFromResult(), which is contained within in the object mysql.(and in the variable $_mysql.) Like this:
$result = $_mysql->arrayFromResult($r);
That's where I get the error. PHP says that the variable '$_mysql' is undefined, but I defined it in the 'mysql.php' file.(see above) I also included mysql.php with the following code:
include_once 'mysql.php';
I have no idea what is wrong! If anyone can help that would be much appreciated.
The source files can be downloaded with the following link: https://www.dropbox.com/sh/bjj2gyjsybym89r/YLxqyNvQdn

Answer 1

That's a common mistake, in the place of definition you need only the line:
$_mysql = new mysql();
and when you want to use it inside a function, only there you have to declare it as a global variable (otherwise it is considered like any other function variable):
global $_mysql;
so, for example, if we'll take your method:
function getTable($tableName) {
$r = mysql_query("SELECT * FROM $tableName");
err($r, 'mysql returned null when getting table!');
$result = $_mysql->arrayFromResult($r);
return $result;
}
it should be changed to:
function getTable($tableName) {
global $_mysql;
$r = mysql_query("SELECT * FROM $tableName");
err($r, 'mysql returned null when getting table!');
$result = $_mysql->arrayFromResult($r);
return $result;
}