PHP 7 Programming Cookbook

Hinting at data types

In many cases when developing functions, you might reuse the same library of functions in other projects. Also, if you work with a team, your code might be used by other developers. In order to control the use of your code, it might be appropriate to make use of a type hint. This involves specifying the data type your function expects for that particular parameter.

How to do it...

1. Parameters in functions can be prefixed by a type hint. The following type hints are available in both PHP 5 and PHP 7:
   • Array
   • Class
   • Callable
2. If a call to the function is made, and the wrong parameter type is passed, a TypeError is thrown. The following example requires an array, an instance of DateTime, and an anonymous function:

   function someTypeHint(Array ...