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IX. Objets
Ces fonctions permettent de g�rer les classes et les objets.
Vous pouvez notamment conna�tre le nom de la classe d'un
objet, ses membres et ses m�thodes, et tous les objets
parents (les classes qui sont �tendues par la classe d'un objet).
Dans cet exemple, on d�finit une classe de base, et une
extension. La classe de base d�finit un l�gume, s'il est
mangeable ou pas, et sa couleur. La sous-classe
epinard ajoute une m�thode pour le cuisiner,
et une autre pour savoir s'il est cuisin�.
Exemple 1. classes.inc <?php
// classe de base, avec ses membres et ses m�thodes
class Legume {
var $mangeable;
var $couleur;
function legume( $mangeable, $couleur="green" ) {
$this->mangeable = $mangeable;
$this->couleur = $couleur;
}
function est_mangeable() {
return $this->mangeable;
}
function quelle_couleur() {
return $this->couleur;
}
} // fin de la classe Legume
// extend la classe de base
class Epinard extends Legume {
var $cuit = FALSE;
function Epinard() {
$this->Legume( TRUE, "green" );
}
function cuisine() {
$this->cuit = TRUE;
}
function est_cuit() {
return $this->cuit;
}
} // fin de la classe Epinard
?> |
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Lorsqu'on instantie deux objets de ces classes, et qu'on affiche
leurs informations, on affiche aussi leur h�ritage. On d�finit ici
des utilitaires qui servent essentiellement � afficher ces
informations proprement.
Exemple 2. test_script.php <pre>
<?php
include "classes.inc";
// utilitaires
function print_vars($obj) {
$arr = get_object_vars($obj);
while (list($prop, $val) = each($arr))
echo "\t$prop = $val\n";
}
function print_methods($obj) {
$arr = get_class_methods(get_class($obj));
foreach ($arr as $method)
echo "\tfunction $method()\n";
}
function class_parentage($obj, $class) {
global $$obj;
if (is_subclass_of($$obj, $class)) {
echo "L'objet $obj belongs to class ".get_class($$obj);
echo " est une sous-classe de $class\n";
} else {
echo "L'objet $obj n'est pas une sous classe $class\n";
}
}
// instantie 2 objets
$legume = new Legume(TRUE,"blue");
$feuilles = new Epinard();
// affiche les informations sur ces objets
echo "legume: CLASS ".get_class($legume)."\n";
echo "feuilles: CLASS ".get_class($feuilles);
echo ", PARENT ".get_parent_class($feuilles)."\n";
// affiche les propri�t�s du l�gume
echo "\nl�gume: Propri�t�s \n";
print_vars($legume);
// et les m�thodes de "feuilles"
echo "\nfeuilles: Methods\n";
print_methods($feuilles);
echo "\nParent�e:\n";
class_parentage("feuilles", "Epinard");
class_parentage("feuilles", "Legume");
?>
</pre> |
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Il est important de noter que dans les exemples ci-dessus, les objets
$feuilles sont une instance de
Epinard qui est une sous-classe de
Legume, donc la derni�re partie du script
va afficher :
User Contributed Notes
Objets |
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[email protected]
08-Mar-2001 07:59 |
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[Editor's note: If you are trying to do overriding, then you can just
interrogate (perhaps in the method itself) about what class (get_class())
the object belongs to, or if it is a subclass of a particular root
class.
You can alway refer to the parent overriden method, see
the "Classes and Objects" page of the manual and
comments/editor's notes therein.]
There is no function to
determine if a member belongs to a base class or current class
eg:
class foo {
function foo () { }
function a () {
}
}
class bar extends foo {
function bar () { }
function a () { }
}
lala = new
Bar();
------------------
how do we find programmatically if
member a now belongs to class Bar or Foo.
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[email protected]
04-Jun-2001 08:27 |
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i came across an error something to the extent:
Fatal error: The
script tried to execute a method or access a property of an incomplete
object.
This was because I had included the file defining the
class when i created the object but not in the script when i was trying to
access the object as a member variable of a different object
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[email protected]
29-Sep-2001 04:10 |
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I spent 20 minutes or so trying to figure this out, maybe someone else has
the same problem.
To access a class' function from within the
class you would have to say $this->functionname(params), rather than
just functionname(params) like in other programming
languages.
Hope this helps
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22-Nov-2001 09:18 |
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New to OOP? This listing of beginner PHP OOP tutorials may help:
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[email protected]
24-Feb-2002 06:34 |
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array in class ^^
class CConfig
{
var $color = array(
'top' => "",
'write' =>
"",
'reply' => "",
'bottom1' => "",
'bottom2' => "",
'bottom3' => ""
);
}
don't do var
color['write'];
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saryon_no_spam_@unfix dot o r g
05-Mar-2002 03:46 |
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Something nice i found out when i was trying to do with classes what i knew
could be done with
functions: they can be dynamically
loaded/used.
ex:
class a
{
function bla()
{
echo "1\n";
}
}
class b
{
function bla()
{
echo "2\n";
}
}
$class =
"a";
$test = new
$class;
$test->bla();
$class2 = "a";
$test2
= new
$class2;
$test2->bla();
-----------------------
This
will print:
1
2
------------------
For those of
you who were considering doing something with plugins....use this to
your
advantage :)
makes life soooo easy, this :)
Sar
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[email protected]
20-Mar-2002 04:39 |
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Actually, that example prints "1" and then "1", rather
than "1" and then "2". I'm assuming the typo is that
it should read $class2 = "b" instead of a.
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c.bolten AT grafiknews DOT de
22-Apr-2002 12:14 |
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another way to dynamically load your classes:
==========================
function loadlib($libname) {
$filename = "inc/".$libname.".inc.php";
//
check if file exists...
if (file_exists($filename)) {
// load library
require($filename);
return
TRUE;
}
else {
// print error!
die ("Could
not load library $libname.\n");
}
}
:)
have
phun!
-cornelius
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[email protected]
29-Apr-2002 03:48 |
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This is a pretty basic data structure, I know, but I come from a C++
background where these things were "da bomb" when I was first
learning to implement them. Below is a class implementation for a queue
(first-in-first-out) data structure that I used in a recent project at my
workplace. I believe it should work for any type of data that's passed to
it, as I used mySQL result objects and was able to pass the object from
one page to another as a form element.
# queue.php
# Define
the queue class
class queue
{
# Initialize class
variables
var $queueData = array();
var $currentItem = 0;
var
$lastItem = 0;
# This function adds an item to the end of the
queue
function enqueue($object)
{
# Increment the last item
counter
$this->lastItem = count($this->queueData);
#
Add the item to the end of the
queue
$this->queueData[$this->lastItem] =
$object;
}
# This function removes an item from the front of
the queue
function dequeue()
{
# If the queue is not
empty...
if(! $this->is_empty())
{
# Get the object at
the front of the queue
$object =
$this->queueData[$this->currentItem];
# Remove the
object at the front of the
queue
unset($this->queueData[$this->currentItem]);
#
Increment the current item
counter
$this->currentItem++;
# Return the
object
return $object;
}
# If the queue is
empty...
else
{
# Return a null value
return
null;
}
}
# This function specifies whether or not the
queue is empty
function is_empty()
{
# If the queue is
empty...
if($this->currentItem >
$this->lastItem)
# Return a value of true
return
true;
# If the queue is not empty...
else
#
Return a value of false
return
false;
}
}
?>
# Examples of the use of the
class
# Make sure to include the file defining the
class
include("queue.php");
# Create a new instance of
the queue object
$q = new queue;
# Get data from a mySQL
table
$query = "SELECT * FROM " . TABLE_NAME;
$result =
mysql_query($query);
# For each row in the resulting
recordset...
while($row = mysql_fetch_object($result))
{
#
Enqueue the row
$q->enqueue($row);
}
# Convert the queue
object to a byte stream for data transport
$queueData =
ereg_replace("\"", """,
serialize($q));
# Convert the queue from a byte stream back to an
object
$q = unserialize(stripslashes($queueData));
# For each
item in the queue...
while(! $q->is_empty())
{
# Dequeue an
item from the queue
$row = $q->dequeue();
}
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[email protected]
19-Aug-2002 03:38 |
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If you want to be able to call an instance of a class from within another
class, all you need to do is store a reference to the external class as a
property of the local class (can use the constructor to pass this to the
class), then call the external method like
this:
$this->classref->memberfunction($vars);
or if
the double '->' is too freaky for you, how
about:
$ref=&$this->classref;
$ref->memberfunction($vars);
This
is handy if you write something like a general SQL class that you want
member functions in other classes to be able to use, but want to keep
namespaces separate. Hope that helps
someone.
Justin
Example:
<?php
class class1
{
function test($var) {
$result = $var + 2;
return $result;
}
}
class class2{
var
$ref_to_class=''; # to be pointer to other class
function
class1(&$ref){ #constructor
$this->ref_to_class=$ref;
#save ref to other class as property of this class
}
function test2($var){
$val =
$this->ref_to_class->test($var); #call other class using ref
return $val;
}
}
$obj1=new class1;
# obj1 is
instantiated.
$obj2=new class2($obj1);
# pass ref to obj1 when
instantiating obj2
$var=5;
$result=obj2->test2($var);
#
call method in obj2, which calls method in obj1
echo
($result);
?>
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com_set