Traits

We mentioned previously that PHP is a single inheritance language. We cannot use the extends keyword to extend multiple classes in PHP. This very feature is actually a rare commodity only a handful of programming languages support, such as C++. For better or worse, multiple inheritance allows some interesting tinkering with our code structures.

The PHP Traits provide a mechanism by which we can achieve these structures, either in the context of code reuse or the grouping of functionality. The trait keyword is used to declare a Trait, as follows:

<?php

trait Formatter
{
  // Trait body
}

The body of a Trait can be pretty much anything we would put in a class. While they resemble classes, we cannot instantiate a Trait itself. We can only use the Trait from another class. To do so, we employ the use keyword within the class body, as shown in the following example:

class Ups
{
  use Formatter;

  // Class body (properties & methods)
}

To better understand how Traits can be helpful...