RE: [PHP] Question regarding OO
> -Original Message- > From: Jay Blanchard [mailto:[EMAIL PROTECTED] > Sent: Friday, July 11, 2008 1:51 PM > To: Eric Butera; php php > Subject: RE: [PHP] Question regarding OO > > [snip] > I understand my error in thinking now. > > Apple can't extend Tree. > > Oak, Evergreen or Willow extend Tree. > > I thank you all for helping me to understand. > [/snip] > > By jove, I think he's got it! > > Parking space could be a member variable of parking lot, that would > make > sense. One thing at a time, Jay... one thing at a time. ;) Todd Boyd Web Programmer -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
RE: [PHP] Question regarding OO
[snip] I understand my error in thinking now. Apple can't extend Tree. Oak, Evergreen or Willow extend Tree. I thank you all for helping me to understand. [/snip] By jove, I think he's got it! Parking space could be a member variable of parking lot, that would make sense. -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Fwd: [PHP] Question regarding OO
-- Forwarded message --
From: Yeti <[EMAIL PROTECTED]>
Date: Fri, Jul 11, 2008 at 2:08 PM
Subject: Re: [PHP] Question regarding OO
To: Eric Butera <[EMAIL PROTECTED]>
I understand my error in thinking now.
Apple can't extend Tree.
Oak, Evergreen or Willow extend Tree.
I thank you all for helping me to understand.
On 7/11/08, Eric Butera <[EMAIL PROTECTED]> wrote:
>
> On Fri, Jul 11, 2008 at 12:03 PM, Yeti <[EMAIL PROTECTED]> wrote:
> > >
> > /*
> >
> > 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 = $max_cars;
> >
> > }
> >
> > };
> >
> > cpark = new ParkingLot(5, 17);
> >
> > // <--- 2nd CLASS
> >
> > class ParkingSpace extends ParkingLot {
> >
> > var ps_ID; // ID of the parking space ( 1 .. max_number_of_cars )
> >
> > var occupied_by; // ID of the car on the parking space
> >
> > var st_time; // Unix time stamp set when the car parks
> >
> > function __construct($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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Re: [PHP] Question regarding OO
On Fri, Jul 11, 2008 at 12:03 PM, Yeti <[EMAIL PROTECTED]> wrote:
>
> /*
>
> 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 = $max_cars;
>
> }
>
> };
>
> cpark = new ParkingLot(5, 17);
>
> // <--- 2nd CLASS
>
> class ParkingSpace extends ParkingLot {
>
> var ps_ID; // ID of the parking space ( 1 .. max_number_of_cars )
>
> var occupied_by; // ID of the car on the parking space
>
> var st_time; // Unix time stamp set when the car parks
>
> function __construct($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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Re: [PHP] Question regarding OO
Corrected code example: (too early in the morning to think) In the above class definition, simply populate the $spaces array with instances of the ParkingSpace class. ~Ted -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Question regarding OO
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.
In the above class definition, simply populate the $spaces array with
instances of the ParkingSpace class.
~Ted
On 11-Jul-08, at 9:03 AM, Yeti wrote:
I have a question here regarding object orientation in PHP and any
other
language.
Let's start with some hypothetical code:
*/
// <--- 1st CLASS
class ParkingLot {
var size; // size in sq feet
var max_number_of_cars; // how many cars there is space for
function __construct($size, $max_cars) {
$this->size = $size; $this->max_number_of_cars = $max_cars;
}
};
cpark = new ParkingLot(5, 17);
// <--- 2nd CLASS
class ParkingSpace extends ParkingLot {
var ps_ID; // ID of the parking space ( 1 .. max_number_of_cars )
var occupied_by; // ID of the car on the parking space
var st_time; // Unix time stamp set when the car parks
function __construct($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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Re: [PHP] Question regarding OO
On Fri, 2008-07-11 at 18:03 +0200, Yeti wrote:
>
> /*
>
> 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(5, 17);
>
> // <--- 2nd CLASS
>
> class ParkingSpace extends ParkingLot {
Here's the point of your comfusion. ParkingSpace is not really a
ParkingLot is it? I mean you could say a parking lot having a single
parking space qualifies, but not really. I see you problem being similar
to apples versus apple tree. You wouldn't do the following (would you?):
Cheers,
Rob.
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Application and Templating Framework for PHP
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[PHP] Question regarding OO
size = $size; $this->max_number_of_cars = $max_cars;
}
};
cpark = new ParkingLot(5, 17);
// <--- 2nd CLASS
class ParkingSpace extends ParkingLot {
var ps_ID; // ID of the parking space ( 1 .. max_number_of_cars )
var occupied_by; // ID of the car on the parking space
var st_time; // Unix time stamp set when the car parks
function __construct($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
*/
?>
