php nesting classes

[christophe.gosiau]

Hi everybody,
I have the following problem:
For an application, I made 2 classes: Order and Ticket
In the Order object I store an array with Ticket objects.
so far so good, now I needed the Order object inside the Ticket class.
So I stored a copy of the Order object inside the Ticket class.

This is what we got until now:

class Order {
pubic tickets = array()
}

class Ticket {
public Order = null
}
For both classes I made static methods: get_by_id()
Now my question: What happens if i do: Ticket::get_by_id(5);
A Ticket object will be created. Inside this Ticket object, an Order
object will be created with the Order::get_by_id($this->orderid)
method.
This Order object will fill his $tickets array wilt the
Ticket::get_by_id($ticketid) method.
Those tickets will create new Order objects...
So there will be a loop.
How will php handle this?
If this causes an error, is there another solution to fix this
problem?

Christophe

[Jerry Stuckle]

ch***************@gmail.com wrote:

Hi everybody,
I have the following problem:
For an application, I made 2 classes: Order and Ticket
In the Order object I store an array with Ticket objects.
so far so good, now I needed the Order object inside the Ticket class.
So I stored a copy of the Order object inside the Ticket class.

This is what we got until now:

class Order {
pubic tickets = array()
}

class Ticket {
public Order = null
}
For both classes I made static methods: get_by_id()
Now my question: What happens if i do: Ticket::get_by_id(5);
A Ticket object will be created. Inside this Ticket object, an Order
object will be created with the Order::get_by_id($this->orderid)
method.
This Order object will fill his $tickets array wilt the
Ticket::get_by_id($ticketid) method.
Those tickets will create new Order objects...
So there will be a loop.
How will php handle this?
If this causes an error, is there another solution to fix this
problem?

Christophe

Christophe,

*WHY* do you need a both a list of tickets in orders and an order in ticket?

Either an order has tickets, or a ticket has orders. But can you
explain how both are true?

--
==================
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Jerry Stuckle
JDS Computer Training Corp.
js*******@attglobal.net
==================

[christophe.gosiau]

Hi Jerry,

My original plan was to to so store Tickets in an array in the Order
object.
But, a ticket needs to be printed (render to pdf). To do that, I need
to know which name I have to print on it (object Customer) and the
event where it is for (object Event).
Both Customer and Event are also stored inside the Order class.
That is the only reason why I need the Order object inside the Ticket
class.

On 22 apr, 04:43, Jerry Stuckle <[e-mail]:

[e-mail] wrote:

Hi everybody,
I have the following problem:
For an application, I made 2 classes: Order and Ticket
In the Order object I store an array with Ticket objects.
so far so good, now I needed the Order object inside the Ticket class.
So I stored a copy of the Order object inside the Ticket class.

This is what we got until now:

class Order {
pubic tickets = array()
}

class Ticket {
public Order = null
}

For both classes I made static methods: get_by_id()
Now my question: What happens if i do: Ticket::get_by_id(5);
A Ticket object will be created. Inside this Ticket object, an Order
object will be created with the Order::get_by_id($this->orderid)
method.
This Order object will fill his $tickets array wilt the
Ticket::get_by_id($ticketid) method.
Those tickets will create new Order objects...
So there will be a loop.
How will php handle this?
If this causes an error, is there another solution to fix this
problem?

Christophe

Christophe,

*WHY* do you need a both a list of tickets in orders and an order in ticket?

Either an order has tickets, or a ticket has orders. But can you
explain how both are true?

--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
[e-mail]
==================

[Jerry Stuckle]

ch***************@gmail.com wrote:

On 22 apr, 04:43, Jerry Stuckle <[e-mail]:

>[e-mail] wrote:

>>Hi everybody,
I have the following problem:
For an application, I made 2 classes: Order and Ticket
In the Order object I store an array with Ticket objects.
so far so good, now I needed the Order object inside the Ticket class.
So I stored a copy of the Order object inside the Ticket class.
This is what we got until now:
class Order {
pubic tickets = array()
}
class Ticket {
public Order = null
}
For both classes I made static methods: get_by_id()
Now my question: What happens if i do: Ticket::get_by_id(5);
A Ticket object will be created. Inside this Ticket object, an Order
object will be created with the Order::get_by_id($this->orderid)
method.
This Order object will fill his $tickets array wilt the
Ticket::get_by_id($ticketid) method.
Those tickets will create new Order objects...
So there will be a loop.
How will php handle this?
If this causes an error, is there another solution to fix this
problem?
Christophe

Christophe,

*WHY* do you need a both a list of tickets in orders and an order in ticket?

Either an order has tickets, or a ticket has orders. But can you
explain how both are true?

--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
[e-mail]
==================

Hi Jerry,

My original plan was to to so store Tickets in an array in the Order
object.
But, a ticket needs to be printed (render to pdf). To do that, I need
to know which name I have to print on it (object Customer) and the
event where it is for (object Event).
Both Customer and Event are also stored inside the Order class.
That is the only reason why I need the Order object inside the Ticket
class.

Top posting fixed

OK, but right now I'm not sure what a "Ticket" is, and what an "Order"
is. Does the order have tickets?

One thing is clear, though - the ticket does not have an order. It uses
information from the order, so should reference the order. But it
should not keep a copy of the order.

And since the Order object itself has Ticket objects, perhaps the you
need an Order::MakeTicket method to create the Ticket object and fill in
the information (including a reference to itself).

Another option here would be to not keep the Order reference in the
Ticket. Rather, since you're storing the Ticket list in the Order
class, have an Order::PrintTicket method. Let the Order class print its
info and the Ticket class print it's info. This way you don't need to
keep even a reference to the Order object in the Ticket object.

But you should never keep a copy of something in your program. What
happens if you change the original, for instance?

P.S. Please don't top post. Thanks.
--
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
js*******@attglobal.net
==================

[Toby A Inkster]

Jerry Stuckle wrote:

Either an order has tickets, or a ticket has orders. But can you
explain how both are true?

I often do this sort of thing. Consider a list of authors and a list of
books that they've written:

<?php
class Author
{
private $surname = '';
private $forename = '';
private $books = array();

function __construct ($surname, $forename='')
{
$this->surname = $surname;
$this->forename = $forename;

if (!strlen($this->surname))
throw new Exception("Authors need a surname!");
}

function get_name ($reverse=FALSE)
{
if (!strlen($this->forename))
return $this->surname;

if ($reverse)
return "{$this->surname}, {$this->forename}";
else
return "{$this->forename} {$this->surname}";
}

function print_catalogue ()
{
print $this->get_name() . "\n";
foreach ($this->books as $b)
print "\t".$b->title."\n";
}

function give_credit (Book $book)
{
$book->author = $this;
$this->books[] = $book;
}
}

class Book
{
public $title;
public $author = NULL;

function __construct ($title)
{
$this->title = $title;

if (!strlen($this->title))
throw new Exception("Books need a title!");
}

function get_reference ()
{
if ($this->author instanceof Author)
return $this->author->get_name().': '.$this->title;
else
return $this->title;
}
}
$library['emma'] = new Book('Emma');
$library['pp'] = new Book('Pride & Prejudice');
$library['ss'] = new Book('Sense & Sensibility');
$library['wh'] = new Book('Wuthering Heights');
$library['dict'] = new Book('Concise Oxford English Dictionary');

$authors['JA'] =new Author('Austen', 'Jane');
$authors['JA']->give_credit($library['emma']);
$authors['JA']->give_credit($library['pp']);
$authors['JA']->give_credit($library['ss']);
$authors['JA']->give_credit(new Book('Love & Freindship'));

$authors['EB'] =new Author('Bronte', 'Emily');
$authors['EB']->give_credit($library['wh']);

print "My library of classic literature...\n\n";
foreach ($library as $book)
print $book->get_reference()."\n";
print "\n";
print "All known works of classic literature...\n\n";
foreach ($authors as $author)
$author->print_catalogue();
print "\n";
?>

Bi-directional links between objects are quite common. All authors have
a list of books; all books have an author. In a more advanced
implementation, there might be a Library class too, and it might be a good
idea to take into account the fact that some books have more than one
author.

--
Toby A Inkster BSc (Hons) ARCS
http://tobyinkster.co.uk/
Geek of ~ HTML/SQL/Perl/PHP/Python*/Apache/Linux

* = I'm getting there!