Basic Classes & Objects problems...

[andy_baptiste]

Hi People,

I'm in the process of switching from Java to php and am having alsorts of problems, for example:

// I'm instanciating an object:
// setting it up
$item = new ProductVO();
$item->setProductCode($productID);
$item->setDescription($productID);
$item->setPrice(10);

// and then retrieving the values I've set
$description=$item->getDescription();
echo($description);

// but this prints absolutely nothing 😕

Another one is where I have an object as a member of another class:

class ShoppingCartDelegate
{

var $cart=null;

function _construct(){$this->cart = new OrderVO();}

function addToCart($productID, $quantity)
{

$orderLines = $this->cart->getOrderLines();

}

}
This errors saying:
The script tried to execute a method or access a property of an incomplete object.

Thanks for any help....

[NogDog]

The problem may be due to your __construct method name only having one underscore (it needs to start with two underscores). Assuming it's not a typo in your post, then with only one underscore it's not being treated as a constructor.

[andy_baptiste]

Oh right..........no it was not a typo, well spotted!

I'll see how many of my issues this sorts...

Thanks for your help.

Both the problems above still happen even with the corrected syntax for php constuctors....any ideas?

[m_tt]

We can't help you if you don't provide the proper code. You asked why $description=$item->getDescription() doesn't return anything, well show us the getDescription() function and maybe we can answer that. As for the second problem, it looks like your problem would be in the OrderVO() class, and you provided no code for that either.

Also i'm not entirely sure, someone please correct me if i'm wrong, but __construct() is PHP5. A PHP4 constructor would be the class name.

Ie:

class MyClass {
// Construct
function MyClass() {

[andy_baptiste]

My apollogies.

The top problem seems to be working now so presume there was a syntax error somewhere, and I'm using php5.

The second problem occures when I do this more than once:
(It was doing it every time until I added __autoload() )

I call addToCartAction.php
It creates a ShoppingCartDelegate and sends an OrderVO off to it
It then calls shoppingCartDelegate->addToCart()
But when ShoppingCartDelegate's addToCart() invokes $this->cart->getOrderLines()

I get:
The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition "OrderVO" of the object you are trying to operate on was loaded before unserialize() gets called or provide a __autoload() function to load the class definition

addToCartAction.php

<?php
include_once('../myphp/ShoppingCartDelegate.inc');
include_once('../myphp/OrderVO.inc');

$shoppingCart = new ShoppingCartDelegate();

if(!$SESSION['cart'])$SESSION['cart']= new OrderVO();

// set cart up in delegate
$shoppingCart->setCart($_SESSION['cart']);

// effect cart
$shoppingCart->addToCart($itemToAdd,$quantity);

// set back in session
$_SESSION['cart']= $shoppingCart->getCart();

?>

ShoppingCartDelegate.inc

<?php
include_once('User.inc');
include_once('UserVO.inc');
require_once('OrderVO.inc');
require_once('OrderLineVO.inc');
include_once('ProductVO.inc');

class ShoppingCartDelegate
{

private $cart;

function construct(){$this->cart = new OrderVO();}
function autoload($class_name) { require_once $class_name.'.inc';}

// takes an OrderVO
public function setCart($cart)
{
$this->cart = $cart;
}

// returns an OrderVO
public function getCart()
{
return $this->cart;
}

// takes String productId, int quantity
public function addToCart($productID, $quantity)
{

$item = new ProductVO();
$item->setProductCode($productID);
$item->setDescription($productID);
$item->setPrice(10);

// cart is an OrderVO and getOrderLines is an array
$orderLines = $this->cart->getOrderLines(); // This is where it errors

}
?>

OrderVO.inc (Is just a simple Value Object)

<?php

class OrderVO
{
private $orderLines= array();

function construct(){$this->orderLines=array();}
function autoload($class_name) { require_once $class_name.'.inc';}

public function getOrderLines(){ return $this->orderLines; }
public function setOrderLines($orderLines){ $this->orderLines=$orderLines; }
}
?>

[andy_baptiste]

This appears to be working now.

Adding this to my classes only seemed to partly fix the problem:
function __autoload($class_name) { require_once $class_name.'.inc';}

But I read somewhere that you "should only have one __autoload method per application"
so I added it to the file that I use as the applications controller.