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Posted by Scott on 03/09/06 21:08
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!
Scott
gardnern wrote:
> 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.
>
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