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Last updated: Sat, 19 Apr 2003

LXXVI. Object property and method call overloading

Einf�hrung

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.

Warnung

Diese Erweiterung ist EXPERIMENTELL. Das Verhalten dieser Erweiterung, einschlie�lich der Funktionsnamen, und alles Andere was hier dokumentiert ist, kann sich in zuk�nftigen PHP-Versionen ohne Ank�ndigung �ndern. Seien Sie gewarnt und verwenden Sie diese Erweiterung auf eigenes Risiko.

Anforderungen

Diese Erweiterung ben�tigt zur Erstellung keine externen Bibliotheken.

Installation

In order to use these functions, you must compile PHP with the --enable-overload option. Starting with PHP 4.3.0 this extension is enabled by default. You can disable overload support with --disable--overload.

The windows version of PHP has built in support for this extension. You do not need to load any additional extension in order to use these functions.

Anmerkung: Builtin support for overload is available with PHP 4.3.0.

Laufzeit Konfiguration

Diese Erweiterung definiert keine Konfigurationseinstellungen in der php.ini.

Resource Typen

Diese Erweiterung definiert keine Resource-Typen.

Vordefinierte Konstanten

Diese Erweiterung definiert keine Konstanten.

Beispiele

Some simple examples on using the overload() function:

Beispiel 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);

?>

Warnung

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.

Inhaltsverzeichnis
overload -- Enable property and method call overloading for a class


User Contributed Notes
Object property and method call overloading
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steve at walkereffects dot com
25-Feb-2003 05:32

If you are a perfectionist when it comes to your class interfaces, and you are unable to use overload(), there is another viable solution:

Use func_num_args() to determine how many arguments were sent to the function in order to create virtual polymorphism. You can create different scenarios by making logical assumptions about the parameters sent. From the outside the interface works just like an overloaded function.

The following shows an example of overloading a class constructor:

class Name
{
     var $FirstName;
     var $LastName;

     function Name($first, $last)
     {
         $numargs = func_num_args();

           if($numargs >= 2)
           {
                 $this->FirstName = $first;
                $this->LastName = $last;
           }
         else
           {
                 $names = explode($first);
                $this->FirstName = $names[0];
                $this->LastName = $names[1]
           }
     }

}

muell-spam-trash-abfall at kcet dot de
14-Mar-2003 02:53

This is the syntax of __get(), __set() and __call():

__get ( [string property_name] , [mixed return_value] )
__set ( [string property_name] , [mixed value_to_assign] )
__call ( [string method_name] , [array arguments] , [mixed return_value] )

__call() seems to work with PHP 4.3.0

See for using this extension in detail.

add a note

<ob_startoverload>
 Last updated: Sat, 19 Apr 2003
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