Introduction
The purpose of this extension is to allow overloading of object
property access and method calls. Only one function is defined
in this extension, overload() 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: __get(),
__set() and __call()
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.
| Warning |
This extension is
EXPERIMENTAL. The behaviour of this extension --
including the names of its functions and anything else documented
about this extension -- may change without notice in a future release of PHP.
Use this extension at your own risk. |
Requirements
No external libraries are needed to build this extension.
Installation
In order to use these functions, you must compile
PHP with the --enable-overload option.
Runtime Configuration
This extension has no configuration directives defined in php.ini.
Resource Types
This extension has no resource types defined.
Predefined Constants
This extension has no constants defined.
Examples
Some simple examples on using the overload()
function:
Example 1. Overloading a PHP class <?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;
print "\$o->a: $o->a\n"; // print: $o->a:
print "\$o->b: $o->b\n"; // print: $o->b: 9
print "\$o->c: $o->c\n"; // print: $o->c: 42
print "\$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);
?> |
|
| Warning |
As this is an experimental extension, not all things
work. There is no __call() support
currently, you can only overload the get and set
operations for properties. You cannot invoke the
original overloading handlers of the class, and
__set() only works to one level
of property access.
|