PHP debug function that provides basic trace info

debug.php

<?php

function X($msg) {
  $nameLen = 20;
  $trace = debug_backtrace();
  $caller = array_shift($trace);
  $date = date('c');
  list($ms) = explode(' ', microtime());
  $line = str_pad($caller['line'], 4, '0', STR_PAD_LEFT);
  $file = str_pad(substr(basename($caller['file'], '.php'), -$nameLen), $nameLen);
  return "$file [$line] ($date $ms) $msg\n";
}