function remove_dw_comments($tpl_source, &$smarty)
{
 return preg_replace("/<!--#.*-->/U","",$tpl_source);
 //去除原tpl文件中的注释，使其在编译后的文件中不显示
}
//注册预过滤器
$smarty->register_prefilter("remove_dw_comments");
$smarty->display("test1.tpl");

function add_header_comment($tpl_source, &$smarty)
{
 return "<"<!-- Created by Smarty! -->\n\" ".$tpl_source;
 //添加头部注释
}
//注册后过滤器
$smarty->register_postfilter("add_header_comment");
$smarty->display('test2.tpl');

function protect_email($tpl_output, &$smarty){
  $tpl_output = preg_replace('!(\S+)@([a-zA-Z0-9\.\-]+\.([a-zA-Z]{2,3}|[0-9]{1,3}))!', '$1%40$2', $tpl_output);
  return $tpl_output;}// register the outputfilter$smarty->register_outputfilter("protect_email");
  $smarty->display("index.tpl");
}
$smarty->register_outputfilter("protect_email");
$smarty->display("index.tpl");