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LXXXV. Object property and method call overloading
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.
| 警告 | 本扩展模块是实验性的。该模块的行为，包括其函数的名称以及其它任何关于此模块的文档可能会在没有通知的情况下随 PHP 以后的发布而改变。我们提醒您在使用本扩展模块的同时自担风险。
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| 警告 |
This extension is not a part of PHP 5. PHP 5 supports __get(), __set() and
__call() natively. See the Overloading in PHP 5 page
for more information.
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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.
PHP 的 Windows 版本已经内置该扩展模块的支持。您无需加载任何附加的扩展库即可使用这些函数。 注:
Builtin support for overload is available with PHP 4.3.0.
Some simple examples on using the overload()
function:
例子 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;
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);
?>
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- 目录
- overload -- Enable property and method call overloading for a class
 add a note
User Contributed Notes
Object property and method call overloading
steve at walkereffects dot com
25-Feb-2003 02:32
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]
}
}
}
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