In this chapter we will move directly into PHP 7, presenting recipes that take advantage of new high performance features. First, however, we will present a series of smaller recipes that serve to illustrate the differences in how PHP 7 handles parameter parsing, syntax, a foreach() loop, and other enhancements. Before we go into depth in this chapter, let's discuss some basic differences between PHP 5 and PHP 7.

PHP 7 introduced a new layer referred to as the Abstract Syntax Tree (AST), which effectively decouples the parsing process from the pseudo-compile process. Although the new layer has little or no impact on performance, it gives the language a new uniformity of syntax, which was not possible previously.

Another benefit of AST is the process of dereferencing. Dereferencing, simply put, refers to the ability to immediately acquire a property from, or run a method of, an object, immediately access an array element, and immediately execute a callback. In PHP 5 such support was inconsistent and incomplete. To execute a callback, for example, often you would first need to assign the callback or anonymous function to a variable, and then execute it. In PHP 7 you can execute it immediately.