Template prefilters are PHP functions that your templates are ran through before they are compiled. This is good for preprocessing your templates to remove unwanted comments, keeping an eye on what people are putting in their templates, etc. Prefilters can be either 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

// put this in your application
function remove_dw_comments($tpl_source, &$smarty)
 return preg_replace("/<!--#.*-->/U","",$tpl_source);

// register the prefilter

{* Smarty template index.tpl *}
<!--# this line will get removed by the prefilter -->