Using classes

1

my problem is how to join 2 classes… i wanted to use the other class inside another class… example

<?
class box {
 
var $arg1;
var $arg2;
 
function box($arg1,$arg2) {
$this->arg1=$arg1;
$this->arg2=$arg2;
}
 
function add() {
return $this->arg1+$this->arg2;
}
}
 
 
class ball {
 
var $arg3;
var $arg4;
 
function ball($arg3,$arg4) {
$this->arg3=$arg3;
$this->arg4=$arg4;
}
 
function multiply() {
return $this->arg3 * $this->arg4;
}
}
?>

now here is the part…

i wanted to have another function inside the class box where i can add and multiply and the multiplication method is by using the class ball… all in all, only 2 classes are used…

tnx… rok on!!!

2

Hi

I don’t altogether understand your problem.

You can either call the $ball->multiply method or make the ball a member of the box.

class box {
 
var $arg1;
var $arg2;
var $ball;  //a ball object
 
function box($arg1,$arg2,$ball) {
$this->arg1=$arg1;
$this->arg2=$arg2;
$this->ball=$ball;
}

I believe it’s called ‘composition’.

so you would call $box->ball->multiply()
You would have to alter your multiply method so it can accept arguments.

3

I don’t think PHP allows for the $box->ball->multiply(); syntax. I’ve tried doing it as well and was forced to do


$ball =& $box->ball;
$ball->multiply();

But that’s possibly cause my server isn’t running the most recent PHP version … not sure.

4

sounds like you may want to extend one of the classes with the other? Making the methods from one avaiable in the other.

5

It allows me to do it in PHP 4.3.10

6

Exactly what it sounds like…look on www.php.net for ‘extends.’
From php.net: *Often you need classes with similar variables and functions to another existing class. In fact, it is good practice to define a generic class which can be used in all your projects and adapt this class for the needs of each of your specific projects. *

7

To use a class ‘inside another class’ you would use composition

My understanding is that to use extends suggests that the extended class is a specialized type of the parent class :-/

Much like the ‘Is A’ vs ‘Has A’ argument in Colin Moock’s Actionscript 2.0 book.

To extend it you’d make a generic ‘shape’ class which had a multiply method and then extend both the box and the ball from that class.

Which has it’s benefits.

:beam:

8

Sounds like either might work:

For Composition See:
http://www.devshed.com/c/a/PHP/Object-Interaction-in-PHP-Introduction-to-Composition-conclusion/

For Extends See:
http://us2.php.net/manual/en/language.oop5.basic.php