New to OO programming

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Ive been using PHP 4 for about 3.5 years now, and havnt messed with
objects and classes for whatever reason, however I know I need to start
using them. With someone who has no class/object programming
experience, php's manual is quite dull and leaves me scratching my
head. Is there a more indepth manual or tutortial somewhere that can
explain everything, and more importantly... I cant figure out why and
when an object/class would be used? Im also switching to PHP 5. Thanks.

Re: New to OO programming

OOP isn't a catch all for everything.  For larger application
development it is a godsend, though.

PHP5 follows most of the OOP principles, and resembles java in many
ways.  Any book, tutorial, information on Object Oriented Programming
will be relevent to PHP's Object model.  There are only a few
exceptions between PHP5 and general OO models that i've run into in the
past (or more precisely, frustration at single inheritance)

Generally, however, objects are used when you have a lot of code that
is similar between projects or other entities in the project, such as
User's information, Database connections, Shopping carts, etc etc.  All
those things are pretty much the same between projects, and can be
extended to do more for any specific application.

I wish i could provide a good resource for you, but i've yet to find
one myself.

Re: New to OO programming

Try and

For a more advanced version you can download and view the code in my sample  
application at

You might also find rather  

Tony Marston

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Re: New to OO programming

I agree - the manual is pretty dull, especially when you don't  
understand the whole purpose behind using OOP.

Richard was right when he said "For larger application development it is  
a godsend, though."  One reason why OOP is the way to go when developing  
larger applications is because it allows you to focus on one particular  
part of the application at a time, instead of trying to constantly keep  
the whole big picture in your head.

For example, let's say you're developing a shopping cart.  Think of the  
cart itself as an object - a real world physical object, like a cart in  
a grocery store.  What purpose does the cart serve?  It holds items. On  
a website, a cart needs to be able to receive and remove items. So your  
initial class would probably start out something like this (I'll do this  
with PHP4 for now for the sake of simplicity):

class cart {

   var $items = array(); // This will hold all the items in the cart

   function addItem($itemNo, $qty) {
     if(isset($this->items[$itemNo])) {
       $this->items[$itemNo]['qty'] += $qty;
     } else {
       $this->items[$itemNo]['qty'] = $qty;

   function removeItem($itemNo, $qty) {
     if(isset($this->items[$itemNo])) {
       $this->items[$itemNo] -= $qty;

Now, what you have is all the code that affects the shopping cart in one  
place. You add properties and methods (vars and functions) based on what  
functionality you want your cart to have.  For example, you'll probably  
want to add a displayContents() function for users to view the contents  
of the cart.

The items you put in the cart can also be objects with properties such  
as price, weight, item number, and name (although you'd need to do your  
addItem function a little differently than I did).  This will make it  
easy to access these properties when you display the cart contents.  
($this->items[$itemNo]->price) or something to that effect.

While PHP 5 has far superior OOP capabilities than PHP 4, it is also  
much more complex. There's a book by W.J. Gilmore called "Beginning PHP  
5 and MySQL: From Novice to Professional".  While this wasn't the best  
PHP book I've read, it did do a good job of explaining OOP in PHP 5.

Hope this helped!


gardnern wrote:
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Re: New to OO programming

Thanks for all the replies, some great info here. Ill read through your
site Tony, and Ill be sure to check out that book Scott. I have W.J.
Gilmores book called "PHP and E-Commerce: From Novice to Professional"
and found it helpfull, so Im sure this one will too. Thanks again.

Re: New to OO programming

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Excellent precis.  Thank you.


Stupendous Tales
Speculative Fiction, Pulp Dreams

Re: New to OO programming

Glad you liked it.  The benefits of OOP were a bit hazy to me until I  
started thinking about it from the physical world aspect.

Scott wrote:
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