Output a PHP string or expression as a HTTP header / Drupal

debug-via-header.php

<?php
/**If a 'debug' parameter is set, output a PHP string or expression, probably as a HTTP header.
 *
 * Inspired by OUVLE ouauth module, and FirePHP.
 *
 * @param mixed $exp A PHP string or expression.
 * @copyright 2012-01-31 N.D.Freear.
 */
function _MY_DRUPAL_MODULE_debug($exp) {
  // For Drupal, try variable_get().
  if ((isset($_GET['debug']) && $_GET['debug']) || variable_get('debug', NULL)) {
    static $count = 0;
    static $where;
    // $where could be based on __FUNCTION__ or debug_backtrace().
    if(!$where)$where = str_replace(array('_','.'), '-', basename(__FILE__));
    @header("X-D-$where-$count: ".json_encode($exp));
    $count++;
  }
}