PSR-2 (by PHP Framework Interoperability Group) does not mention short array syntax. But as you can see in chapter 4.3 they use short array syntax to set the default value of
$arg3 to be an empty array.
So for PHP >= 5.4 the short array syntax seems to be the de-facto standard. Only use
array() , if you want your script to run on PHP <5.4.