How to change a class variable in PHP? - undefined

Question

I'm sure there is an easy answer to this question, but for the life of me, I can't find it. I'm using PHP5 and I'm trying to change the value of a class variable, but it doesn't appear to change. For example, I have something like this:
<?php
include_once "../includes/global.php";
loadDAOs('yweightGroups','yweightCourses','yweightUsers','user','yweightData');
class yweight {
private $header_includes;
private $user;
private $yweightUser;
//Description:
// Constructor.
//Parameters:
// -none-
//Returns:
// -nothing-
function __construct() {
global $r_action;
global $r_page;
$this->user = login_required();
if(!$this->user || empty($this->user)){
die();
goHome();
}
$this->header_includes = "";
if(isset($r_action)) {
$this->$r_action();
}
else if (isset($r_page)) {
$this->$r_page();
}
else {
$this->draw();
}
}
//Description:
// Draws the YWeight page
//Parameters:
// -none-
//Returns:
// -nothing-
function draw() {
global $r_page;
global $colorDAO;
global $yweightUsersDAO;
ob_start();
?>
<script type='text/javascript' src="./yweight.js"></script>
<link rel="stylesheet" type="text/css" href="yweight.css" />
<?php
$this->header_includes .= ob_get_clean();
$col = $colorDAO->read(17);
print_top("",$this->header_includes,"resources","",$col->value,$col->fontcolor);
$users = $yweightUsersDAO->GetByUserID($this->user->id);
if(!$users){
echo "<div class='msg_failed'>You are not authorized to view this page.</div>";
die();
}
$this->yweightUser = $users;
echo serialize($this->yweightUser[0]);
?>
<div id="yweight_area"></div>
<script type='text/javascript'>
<?php
if($users[0]->yweightUsers_intern == 0)
echo "drawPage('main_participant');";
else
echo "drawPage('main_intern');";
?>
</script>
<?php
print_bottom();
echo ob_get_clean();
}
//Description:
// Draws the main intern page.
//Parameters:
// -none-
//Returns:
// -nothing-
function main_intern() {
ob_start();
echo "hello intern";
echo ob_get_clean();
}
//Description:
// Draws the main participant page.
//Parameters:
// -none-
//Returns:
// -nothing-
function main_participant() {
global $yweightDataDAO;
ob_start();
$this->yweightUser = $this->yweightUser[0];
echo serialize($this->yweightUser);
?>
<div id="banner_div">
<img class="banner" width="927" src="images/ParticipantsMain.jpg" />
<img id="tracker_btn" class="std_btn" src="images/trackerButton.png" />
<img id="summary_btn" class="std_btn" src="images/summaryButton.png" />
<img id="requirements_btn" class="std_btn" src="images/reqButton.png" />
</div>
<div id="discussion_board_input_div">
<textarea id="discussion_board_input" />
<?php
echo build_btn("green",100,25,"Submit","","","","",
'submit_post()',"margin-top:5px; margin-bottom:5px; float:right;");
?>
<div class="clear_floats" />
</div>
<div id="discussion_board_div">
</div>
<?php
echo ob_get_clean();
}
function submit_post(){
global $yweightDataDAO;
global $userDAO;
global $r_post;
echo serialize($this->yweightUser);
$userDataID = $yweightDataDAO->GetByUserID($this->yweightUser->user_id);
if($userDataID){
$userData = $yweightDataDAO->read($userDataID);
$userDiscussion = unserialize($userData->yweightData_discussionBoard);
}
$userDiscussion[$this->user->firstName . time()] = $r_post;
$userData->yweightData_discussionBoard = serialize($userDiscussion);
$yweightDataDAO->save($userData);
}
}
$recs = new yweight();
?>
submit_post() is an ajax called function. The error I'm getting is that it says $this->yweightUser is undefined. I didn't orignally include all of the code because I thought that I was just misunderstanding how class variables are declared.

Answer 1

You have a typo. Use __construct. Two (_ _) underscores. Your fooVariable is never getting set. After it gets set it works fine.
Update: You only set $this->yweightUser in your function draw() method. If you don't call draw() before ajax_post() or w/e, it will not be defined.

Answer 2

As mentioned above, fix the syntax errrors and it works, 2 underscores for the constructor and opening brace for the constructor and also brackets for arguments:
class foo {
protected $fooVariable;
function __construct () {
$this->fooVariable = "hello world";
$this->changeVariable();
}
function changeVariable(){
$this->fooVariable = "goodbye world";
$this->echoVariable();
}
function echoVariable(){
echo $this->fooVariable;
}
}
$foo = new foo();