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.
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.
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.
Note: Builtin support for overload is available with PHP 4.3.0.
Some simple examples on using the overload() function:
Example 1. Overloading a PHP class
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.