Object-oriented programming, with it's "class" and "object" approach,
is meant to model real life more closely than functional programming.
In, a "parking space" is physically inside a "parking lot", but a
parking space is not a subclass of a parking lot. It's not a variation
or mini parking lot. It's an entirely different entity. A parking lot
consists of parking spaces, but a parking space is its own thing.
In other words, don't extend ParkingSpace from ParkingLot. They should
be separate classes entirely.
As for the recursion... no, that won't be a problem. Each ParkingSpace
you're instantiating is a separate instance, and won't be related to
the parent ParkingLot in anyway way internally.
<?php
class ParkingSpace {
var $size;
var $num_spaces;
var $spaces = array();
}
class ParkingSpace {
var $ps_ID;
var $occupied_by;
var $st_time;
}
?>
In the above class definition, simply populate the $spaces array with
instances of the ParkingSpace class.
~Ted
On 11-Jul-08, at 9:03 AM, Yeti wrote:
<?php
/*
I have a question here regarding object orientation in PHP and any
other
language.
Let's start with some hypothetical code:
*/
// <--- 1st CLASS
class ParkingLot {
var size; // size in sq feet
var max_number_of_cars; // how many cars there is space for
function __construct($size, $max_cars) {
$this->size = $size; $this->max_number_of_cars = $max_cars;
}
};
cpark = new ParkingLot(50000, 17);
// <--- 2nd CLASS
class ParkingSpace extends ParkingLot {
var ps_ID; // ID of the parking space ( 1 .. max_number_of_cars )
var occupied_by; // ID of the car on the parking space
var st_time; // Unix time stamp set when the car parks
function __construct($car, $id) {
$this->st_time = time();
$this->occupied_by = $car;
$this->ps_ID = $id;
}
};
/*
OK, so i got a parking lot class and its subclass parking space.
Now the question:
I want a list of occupied parking spaces, where do I put that? One
might put
it into the ParkingLot Class, but wouldn't that be a recursion (a
child
instance in the parent class)?
*/
$occ_parking_spaces = array();
$occ_parking_spaces[] =& new ParkingSpace('Joes Car', 8);
$occ_parking_spaces[] =& new ParkingSpace('My Prshe', 17);
$occ_parking_spaces[] =& new ParkingSpace('Toms Caddy', 4);
/*
After a while a method to print all occupied spaces is necessary.
Correct me
if I'm wrong, but I usually add it to the ParkingLot class.
class ParkingLot {
// previous code ...
var $occ_parking_spaces = array();
function print_occ_spaces() {
var_dump($this->occ_parking_spaces)
}
};
What bothers me here is that I'm actually having a list of child
classes in
the parent class, is there a better/correct way to do this?
I hope I made myself clear.
Greetz,
Yeti
*/
?>
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