Is using the directory separator constant neccessary?

Question

I am using PHP, but I guess this question might be language agnostic.

With PHP, a constant is defined by PHP, called DIRECTORY_SEPARATOR. I have seen this in Joomla

define('DS', DIRECTORY_SEPARATOR); // quicker to type plus DS is easier to read in a path

I thought this looked like a good idea so I incorporated it into some of my sites. Now I'm asking myself why. I have only experience on Windows and OS X (One day Linux...) and from what I know Microsoft, Linux and Apple all use the forward slash as the directory separator.

I know it might help if one day someone changes the directory separator, but that's unlikely in the foreseeable future (at least I think so).

Is using this constant unnecessary?

Answer 1

Mac OS Classic uses ":", for instance. See Wikipedia for details. Also it's considered good style avoiding 'magic numbers' or similar constructs.

Answer 2

Windows actually uses a backslash as the directory separator, although some environments that have Windows versions will translate between forward slashes and backslashes automatically (Python comes to mind).