Section 11th-overloading-Classes and Objects in php5[11]

OBJECT|PHP5 | = This article is for Haohappy read <<core PHP programming>>
| = Notes from the chapter classes and objects
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Section 11th-Overloading

There is already an overloaded syntax in PHP4 to build mappings to the external object model, just like Java and COM. PHP5 brings a powerful object-oriented overload that allows programmers to establish custom behavior to access properties and invoke methods.

Overloads can be performed by __get, __set, and __call several special methods. PHP calls these methods when the Zend engine attempts to access a member and is not found.

In example 6.14, __get and __set Replace all access to an array of property variables. If necessary, you can implement any type of filter you want. For example, a script can disallow setting property values, starting with a certain prefix or containing a certain type of value.

The __call method shows how you can invoke an undefined method. When you call an undefined method, the method name and the parameters received by the method are passed to the __call method, and PHP passes the __call value back to the undefined method.

Listing 6.14 User-level Overloading
<?php
Class Overloader
{
Private $properties = Array ();

function __get ($property _name)
{
if (Isset ($this->properties[$property _name]))
{
Return ($this->properties[$property _name]);
}
Else
{
return (NULL);
}
}

function __set ($property _name, $value)
{
$this->properties[$property _name] = $value;
}

function __call ($function _name, $args)
{
Print ("Invoking $function _name () <br>n");
Print ("Arguments:");
Print_r ($args);

return (TRUE);
}
}
$o = new Overloader ();

Invoke __set () assigns a value to a nonexistent property variable, activating the __set ()
$o->dynaprop = "Dynamic Content";

Invoke __get () activate __get ()
Print ($o->dynaprop. "<br>n");

Invoke __call () activate __call ()
$o->dynamethod ("Leon", "Zeev");
?>