class Exception

def backtrace_string(current_location = nil)
  if current_location.nil?
    location = nil
  else
    location = "in #{current_location} "
  end
  current_thread = Thread.current
  if !(thread_id = current_thread[:id])
    current_thread.to_s =~ /:(0x[0-9a-f]+)/i
    thread_id = $1 || '?'
  end
  if thread_name = current_thread[:name]
    thread_name = "(#{thread_name})"
  end
  return "*** Exception #{self.class} #{location}" <<
    "(#{self}) (process #{$$}, thread #{thread_id}#{thread_name}):\n" <<
    "\tfrom " << backtrace.join("\n\tfrom ")
end