registered or loaded from the plugins directory by using load_filter() function or by setting $autoload_filters variable. smarty will pass the template source code as the first argument, and expect the function to return the resulting template source code.

模板后过滤器是一些PHP函数，模板就是在那些函数编译后才运行。这样有利于预先处理你的模板，删除不不需要的内容，监视对模板进行的操作，例如：预过滤器同样能够通过 load filter() 函数和设置 $autoload filters 变量来注册或者从工具目录里载入。SMARTY将传递模板输出作为第一个参数，通过自定义函数返回处理结果。

Example 15-2. using a template prefilter <?php // put this in your application function remove_dw_comments($tpl_source, &$smarty) { return preg_replace("/<!--#.*-->/U","",$tpl_source); } // register the prefilter $smarty->register_prefilter("remove_dw_comments"); $smarty->display("index.tpl"); ?> {* Smarty template index.tpl *} <!--# this line will get removed by the prefilter -->