LXIII. Object property and method call overloading


This module is EXPERIMENTAL. That means, that the behaviour of these functions, these function names, in concreto ANYTHING documented here can change in a future release of PHP WITHOUT NOTICE. Be warned, and use this module at your own risk.

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.

Some simple examples on using the overload() function:

Example 1. Overloading a PHP class


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

$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);




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.

Table of Contents
overload -- Enable property and method call overloading for a class