c comment macro

a.c

DEFUN ("or", For, Sor, 0, UNEVALLED, 0,
       doc: /* Eval args until one of them yields non-nil, then return that value.
The remaining args are not evalled at all.
If all args return nil, return nil.
usage: (or CONDITIONS...)  */)
  (Lisp_Object args)
{
  Lisp_Object val = Qnil;

  while (CONSP (args))
    {
      Lisp_Object arg = XCAR (args);
      args = XCDR (args);
      val = eval_sub (arg);
      if (!NILP (val))
	break;
    }

  return val;
}