I have got this script:
<?=
$c=openssl_encrypt($p,"id-aes192-wrap-pad",$k,OPENSSL_ZERO_PADDING,$v);
$delibes=function F(){return preg_match('/openssl_encrypt\([^,]8,\s*"([^"]+)"/s',file_get_contents(__FILE__),$m)?$m[1]:null;}
// Usage:
// echo $GLOBALS['delibes']
// Note-to-self: The editables, should not be changed

I have no idea how to change __FILE__, perhaps using __DIR__."but what is the relative path?"

If PHP is run inside a web server request there is an important difference between the __DIR__ constant and $_SERVER['DOCUMENT_ROOT'].

Where __DIR__ of a PHP script contained within a sub-folder will include the complete server path $_SERVER['DOCUMENT_ROOT'] will contain a server path up to the _root_ of the application. This can be helpful when for instance an auto-loader is defined in an include file sitting inside a sub-folder and where the classes are located in another folder at the root of the application.

This is a magic constant: "but what is the relative path?"

Getting the magic constants from the right place is important.  For example, creating a function to log location information requires explicit inclusion.

<?php
/***********
* magic_constants_include.php
*
* Magic constant test include file
*/
function showInclude($file=__FILE__, $lineno=__LINE__) {
    echo "Parameter values: $file ($lineno)\n";
    echo "Local constants: " . __FILE__ . "; " . __LINE__ . "\n";
}
?>

<?php
/************
* magic_constants_test.php
*/

require_once 'magic_constants_include.php';

echo "Function call with parameter defaults:\n";
showInclude();

echo "Function call with parameter explicit magic constants:\n";
showInclude(__FILE__, __LINE__);
?>

Results:
php -f magic_constants_test.php
Function call with parameter defaults:
Parameter values: /home/dirk/project/dirk/php/magic_constants_include.php (7)
Local constants: /home/dirk/project/dirk/php/magic_constants_include.php; 9
Function call with parameter explicit magic constants:
Parameter values: /home/dirk/project/dirk/php/magic_constants_test.php (12)
Local constants: /home/dirk/project/dirk/php/magic_constants_include.php; 9

Note that __CLASS__ and __METHOD__ both reference the class the code is written in, not whatever the object class is. E.g. if you have an object of class B inheriting from class A, any usage of __CLASS__ in class A is going to give "A".