Smarty的模板中不允许PHP的代码？

/******************************************************************************
 *                  Smarty的模板中不允许PHP的代码？
 * 说明：
 *     在将PHP的代码转换为Smarty的模板的过程中，遇到Smarty无法转换PHP代码的问题，
 * 原因是这个功能被禁止了，因为既然使用Smarty模板，那么PHP代码做的事情尽量放在
 * Controller那里，这样可读性会更高。
 *
 *                                         2017-3-13 深圳 南山平山村 曾剑锋
 *****************************************************************************/

一、参考文档：
    1. Using PHP code in Smarty tpl FIle        
        http://stackoverflow.com/questions/7446851/using-php-code-in-smarty-tpl-file
    2. Using PHP inside Smarty template files [duplicate]
        http://stackoverflow.com/questions/14877736/using-php-inside-smarty-template-files
    3. How to add PHP code to .tpl file [duplicate]
        http://stackoverflow.com/questions/9601547/how-to-add-php-code-to-tpl-file
    4. Using PHP code in Smarty tpl FIle
        http://stackoverflow.com/questions/7446851/using-php-code-in-smarty-tpl-file
    5. Difference between Smarty and SmartyBC classes
        http://stackoverflow.com/questions/35863410/difference-between-smarty-and-smartybc-classes

二、原因：
    1. SmartyBC is a Backwards Compatibility Wrapper. it allows {php} and {include_php} inside templates. Both tags were dropped with the Smarty 3.1 release.
    2. You shouldn't add PHP code to the template. It will make whole idea of templates spoiled. You have to add PHP code to controller, not template.