OOP class question

centenial

Hi,

I have 2 different classes.

1) MySQL - class.mysql.php
2) Cart - class.cart.php

The MySQL class allows me to efficiently write/execute queries. The cart class has functions like AddToCart, UpdateCart, and DeleteFromCart. However, to perform those functions I need to connect to the database and execute a query.

What is the best way to 'include' the functionality contained in the MySQL class to the Cart class? Should I do a "class extend", or simply 'include' the class.mysql.php file and create a new instance of the database class in each function?

Or could I create one instance of the MySQL class ($MYSQL = new MySQL😉 at the top of the Cart class and would that apply to all the functions within the Cart class?

I'd like to do this the "right way", so any help would definitely be appreciated!

ahundiak

There is no single right way though extending the database class to be a cart class would be a wrong way.

I'd suggest injecting the database class into the cart class.

$db = new Mysql();
$cart = new Cart($db);

But again, there are many valid approaches.

dougal85

Just as a quick note. if you are programming in PHP4 you should pass in the class by reference.


$db = &new Mysql();
$cart = new Cart($db);

This is because the default action in PHP4 is to copy the object, in PHP it automatically passes by reference. Copying the object is more time consuming as its copied all over the code.

ahundiak

dougal85 wrote:
Just as a quick note. if you are programming in PHP4 you should pass in the class by reference.
$db = &new Mysql();
$cart = new Cart($db); 
This is because the default action in PHP4 is to copy the object, in PHP it automatically passes by reference. Copying the object is more time consuming as its copied all over the code.

Doesn't hurt to pass it by reference but technically a copy is only made if an actual change to the object is made. And since one should not be updating $db in the cart class, there should not be a problem.

dougal85

I guess your right, I just wanted to add in that suggestion because who knows how much his mySQL class actually does. for all i know some things in it could change.