Ze’ev Suraski began by giving a brief technical history of the PHP language. PHP 1 and 2 were developed around 1995. PHP 3, which started using lex/yacc more efficiently, was released in June 1998, execute while parsing. PHP 4 (May 2000) greatly improved performance (swtiched to a “compile first/execute later” paradigm, added reference counting) and improved the web server and extension APIs.
Zend Engine 2 uses a Java-like object model. All objects will be passed by reference, not by value. Other improvments include $obj->foo()->bar() dereferencing, __clone(), destructors (objects may define a __destruct() function), and unified constructors, and static class variables. It also adds some support for namespaces, exceptions (try, catch, and throw). In the future, Zend Engine 2 might add multiple inheritance and private member variables.
Suraski went on to show some demos of the Zend Engine 2, pointing out how much easier it is to do things like design patterns when you have an objects-are-references system. He showed an example of a factory method that just didn’t work without adding 4 ampersands in strategic locations. We also saw demos of the clone, destructor, and debug backtrace features.
All of his demos used the Zend Studio IDE which seems to have pretty good syntax highlighting, integrated debugger, and a nice help system.
Although the static class variables are a great idea, I didn’t love the self::$foo syntax you had to use to access them. Coming from a C++ and Java background, I would expect that $this->$foo syntax to work on the class variable (instead of dynamically creating an instance variable of the same name).