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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.12 $ -->
<!-- State: deprecated -->
<reference id="ref.overload">
<title>Object property and method call overloading</title>
<titleabbrev>Object overloading</titleabbrev>
<partintro>
<section id="overload.intro">
&reftitle.intro;
<para>
The purpose of this extension is to allow overloading of object
property access and method calls. Only one function is defined
in this extension, <function>overload</function> which
takes the name of the class that should have this functionality
enabled. The class named has to define appropriate methods if
it wants to have this functionality: <literal>__get()</literal>,
<literal>__set()</literal> and <literal>__call()</literal>
respectively for getting/setting a property, or calling a method.
This way overloading can be selective. Inside these handler
functions the overloading is disabled so you can access object
properties normally.
</para>
&warn.experimental;
<warning>
<para>
This extension is not a part of PHP 5. PHP 5 supports <literal>__get()</literal>, <literal>__set()</literal> and
<literal>__call()</literal> natively. See the <link
linkend="language.oop5.overloading">Overloading in PHP 5</link> page
for more information.
</para>
</warning>
</section>
<section id="overload.requirements">
&reftitle.required;
&no.requirement;
</section>
&reference.overload.configure;
<section id="overload.configuration">
&reftitle.runtime;
&no.config;
</section>
<section id="overload.resources">
&reftitle.resources;
&no.resource;
</section>
<section id="overload.constants">
&reftitle.constants;
&no.constants;
</section>
<section id="overload.examples">
&reftitle.examples;
<para>
Some simple examples on using the <function>overload</function>
function:
<example>
<title>Overloading a PHP class</title>
<programlisting role="php">
<![CDATA[
<?php
class OO {
var $a = 111;
var $elem = array('b' => 9, 'c' => 42);
// Callback method for getting a property
function __get($prop_name, &$prop_value)
{
if (isset($this->elem[$prop_name])) {
$prop_value = $this->elem[$prop_name];
return true;
} else {
return false;
}
}
// Callback method for setting a property
function __set($prop_name, $prop_value)
{
$this->elem[$prop_name] = $prop_value;
return true;
}
}
// Here we overload the OO object
overload('OO');
$o = new OO;
echo "\$o->a: $o->a\n"; // print: $o->a: 111
echo "\$o->b: $o->b\n"; // print: $o->b: 9
echo "\$o->c: $o->c\n"; // print: $o->c: 42
echo "\$o->d: $o->d\n"; // print: $o->d:
// add a new item to the $elem array in OO
$o->x = 56;
// instantiate stdclass (it is built-in in PHP 4)
// $val is not overloaded!
$val = new stdclass;
$val->prop = 555;
// Set "a" to be an array with the $val object in it
// But __set() will put this in the $elem array
$o->a = array($val);
var_dump($o->a[0]->prop);
?>
]]>
</programlisting>
</example>
</para>
</section>
</partintro>
&reference.overload.functions;
</reference>
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