On Fri, Jul 11, 2008 at 12:03 PM, Yeti <yeti@xxxxxxxxxx> 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
>
> */
>
> ?>
>
Listen to what everyone else has said so far. Look up IS-A versus
HAS-A. Favor composition over inheritance. You want your parking lot
to have spaces, but spaces don't have to be in a parking lot.
http://www.javacamp.org/moreclasses/oop/oop5.html
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