Most developers wlll be able to switch to the new version without having to change a single line of code. One of the most eagerly awaited new features is the integrated session support. The session API uses an abstracted data-handling mechanism, which allows you to store session data in different ways. The COM support has also been improved and allows instantiation of more sophisticated components now. You create new instances of a COM component with the predefined COM class by passing the component's name as constructor.
Overloaded objects are just one of the many enhancements behind the curtains.
The core engine is only responsible for parsing PHP code, and as such defines the syntax of the programming language. The core is named Zend, a combination of the two main developer's first names, Zeev and Andi. This makes it easy to integrate PHP with other servers. In accordance with this separation of tasks, the parser engine was completely rewritten. PHP 4.0 refuses to do anything with broken scripts, and will display an error message instead.