Description:
------------
hello,

const is too restrictive in PHP.

I think it could be a good idea that the following code worked as expected.

If the constant is not defined, PHP could print a NOTICE and use the name of the constant instead.

Reproduce code:
---------------
<?

define("ROOT", $_SERVER['DOCUMENT_ROOT']);

class FIIFO {

	const PATH = ROOT."/path/to/this/class";



}
?>

Expected result:
----------------
As PATH is a constant,

(FIIFO::PATH == "/www/path/to/this/class") for example.



Actual result:
--------------
A parse error...