PHP Constants Containing Arrays?

Question

This failed:

 define('DEFAULT_ROLES', array('guy', 'development team'));

Apparently, constants can't hold arrays. What is the best way to get around this?

define('DEFAULT_ROLES', 'guy|development team');

//...

$default = split(DEFAULT_ROLES, '|');

This seems like unnecessary effort.

Answer 1

Constants can only contain scalar values, I suggest you store the serialization (or JSON encoded representation) of the array.

Answer 2

Can you not just do:

$DEFAULT_ROLES = array('guy', 'development team');

Answer 3

You can store them as static variables of a class:

class Constants {
    public static $array = array('guy', 'development team');
}
# Warning: array can be changed lateron, so this is not a real constant value:
Constants::$array[] = 'newValue';

If you don't like the idea that the array can be changed by others, a getter might help:

class Constants {
    private static $array = array('guy', 'development team');
    public static function getArray() {
        return self::$array;
    }
}
$constantArray = Constants::getArray();

Answer 4

I agree with eyze, constants tend to be single value values needed for the entire life of your application. You might think about using a configuration file instead of constants for this sort of thing.

If you really need constant arrays, you could use naming conventions to somewhat mimic arrays: for instance DB_Name, DB_USER, DB_HOST, etc.

Answer 5

That is correct, you cannot use arrays for a constant, only scaler and null. The idea of using an array for constants seem a bit backwards to me.

What I suggest to do instead is define your own constant class and use that to get the constant.

Answer 6

You can also serialize your array and then put it into the constant:

# define constant, serialize array
define ("FRUITS", serialize (array ("apple", "cherry", "banana")));

# use it
$my_fruits = unserialize (FRUITS);

HTH, flokra

Answer 7

But you can convert an whole array to constants see link text