Constant arrays

There are two types of constants in PHP, the constants and the class constants. The constants can be defined pretty much anywhere using the define construct, while the class constants are defined within the individual class or interface using the const keyword.

While we cannot say that one type of constant is more important than the other, PHP 5.6 made the difference between the two by allowing class constants with the array data type. Aside from that difference, both types of constants supported scalar values (integer, float, string, Boolean, or null).

The PHP 7 release addressed this inequality by adding the array data type to constants as well, making the following into valid expressions:

// The class constant - using 'const' keyword
class Rift {
  const APP = [
    'name' => 'Rift',
    'edition' => 'Community',
    'version' => '2.1.2',
    'licence' => 'OSL'
  ];
}

// The class constant - using 'const' keyword
interface IRift {
  const APP = [
    'name' => 'Rift',
    'edition' => 'Community',
    'version' => '2.1.2',
    'licence' => 'OSL'
  ];
}

// The constant - using 'define' construct
define('APP', [
  'name' => 'Rift',
  'edition' => 'Community',
  'version' => '2.1.2',
  'licence' => 'OSL'
]);

echo Rift::APP['version'];
echo IRift::APP['version'];
echo APP['version'];

Though having constants with the array data type might not be an exciting type of feature, it adds a certain flavor to the overall constant use.