Core PHP Programming, Third Edition

6.11. User-Level Overloading

PHP 4 introduced the ability for module developers to overload the object-oriented syntax and create mappings into external object models, such as Java or COM. PHP 5 brings the power of object-oriented overloading syntax to PHP developers, allowing them to create custom behaviors for accessing properties and invoking methods.

User-level overloading is done by defining one or more of the following special methods: __get, __set, and __call. PHP calls these methods when the Zend Engine attempts to access a member and does not find it in the current scope.

In Listing 6.14 __get and __set relay all property accesses to the properties array. If necessary, you can implement any kind of filtering you wish. For example, the ...