Zend Framework Smarty extension implementation method

<?php
/**
* Zend_View_Interface
*/
require_once &#39;Zend/View/Interface.php&#39;;
/**
* Smarty 
*/
require_once("smarty/Smarty.class.php");
/**
* 创建Smarty视图
*/
class Zend_View_Smarty implements Zend_View_Interface
{
  /**
   * Smarty object
   * @var Smarty
   */
  protected $_smarty;
  /**
   * Constructor
   *
   * @param string $tmplPath
   * @param array $extraParams
   * @return void
   */
  public function __construct($tmplPath = null, $extraParams = array())
  {
    $this->_smarty = new Smarty;
    if (null !== $tmplPath) {
      $this->setScriptPath($tmplPath);
    }
    foreach ($extraParams as $key => $value) {
      $this->_smarty->$key = $value;
    }
  }
  /**
   * Return the template engine object  
   *
   * @return Smarty
   */
  public function getEngine()
  {
    return $this->_smarty;
  }
  /**
   * Set the path to the templates
   *
   * @param string $path The directory to set as the path.
   * @return void
   */
  public function setScriptPath($path)
  {
    if (is_readable($path)) {
      $this->_smarty->template_dir = $path;
      return;
    }
    throw new Exception(&#39;Invalid path provided&#39;);
  }
  /**
  * set smarty缓存
  * @author lengfeng
  */
  public function setCompilePath($path){
    if (is_readable($path)) {
      $this->_smarty->compile_dir = $path;
      return;
    }
    throw new Exception(&#39;Invalid path provided&#39;);    
  }
  /**
  * set smarty 编译后文档
  * @author lengfeng
  */
  public function setCachePath($path){
    if (is_readable($path)) {
      $this->_smarty->cache_dir = $path;
      return;
    }
    throw new Exception(&#39;Invalid path provided&#39;);    
  }
  /**
   * Retrieve the current template directory
   *
   * @return string
   */
  public function getScriptPaths()
  {
    return array($this->_smarty->template_dir);
  }
  /**
   * Alias for setScriptPath
   *
   * @param string $path
   * @param string $prefix Unused
   * @return void
   */
  public function setBasePath($path, $prefix = &#39;Zend_View&#39;)
  {
    return $this->setScriptPath($path);
  }
  /**
   * Alias for setScriptPath
   *
   * @param string $path
   * @param string $prefix Unused
   * @return void
   */
  public function addBasePath($path, $prefix = &#39;Zend_View&#39;)
  {
    return $this->setScriptPath($path);
  }
  /**
   * Assign a variable to the template
   *
   * @param string $key The variable name.
   * @param mixed $val The variable value.
   * @return void
   */
  public function __set($key, $val)
  {
    $this->_smarty->assign($key, $val);
  }
  /**
   * Retrieve an assigned variable
   *
   * @param string $key The variable name.
   * @return mixed The variable value.
   */
  public function __get($key)
  {
    return $this->_smarty->get_template_vars($key);
  }
  /**
   * Allows testing with empty() and isset() to work
   *
   * @param string $key
   * @return boolean
   */
  public function __isset($key)
  {
     return (null !== $this->_smarty->get_template_vars($key));
  }
  /**
   * Allows unset() on object properties to work
   *
   * @param string $key
   * @return void
   */
  public function __unset($key)
  {
    $this->_smarty->clear_assign($key);
  }
  /**
   * Assign variables to the template
   *
   * Allows setting a specific key to the specified value, OR passing an array
   * of key => value pairs to set en masse.
   *
   * @see __set()
   * @param string|array $spec The assignment strategy to use (key or array of key
   * => value pairs)
   * @param mixed $value (Optional) If assigning a named variable, use this
   * as the value.
   * @return void
   */
  public function assign($spec, $value = null)
  {
    if (is_array($spec)) {
      $this->_smarty->assign($spec);
      return;
    }
    $this->_smarty->assign($spec, $value);
  }
  /**
   * Clear all assigned variables
   *
   * Clears all variables assigned to Zend_View either via {@link assign()} or
   * property overloading ({@link __get()}/{@link __set()}).
   *
   * @return void
   */
  public function clearVars()
  {
    $this->_smarty->clear_all_assign();
  }
  /**
   * Processes a template and returns the output.
   *
   * @param string $name The template to process.
   * @return string The output.
   */
  public function render($name)
  {
    return $this->_smarty->fetch($name);
  }
  /**
   * 设置是否生成缓存
   * 如果没有参数,默认为true
   */
  public function setCache($bool){
     if (isset($bool)) {
      $this->_smarty->caching = $bool;
      return;
    }
  }
}

dir.compile    = ../app/compile
dir.cache    = ../app/cache

/**
* 初始化smarty视图
*
*/
private function _initSmartyView()
{
    $view = new Zend_View_Smarty();
    $view->setBasePath($this->_pathConfig->dir->viewBase);
    $view->setScriptPath($this->_pathConfig->dir->viewBase."/scripts");
    $view->setCompilePath($this->_pathConfig->dir->compile);
    $view->setCachePath($this->_pathConfig->dir->cache);
    $smarty=$view->getEngine();
    $smarty->caching=false;
    $smarty->debugging = true;
    $smarty->compile_check = true;    
    $smarty->left_delimiter = "<{"; //定义标示符
    $smarty->right_delimiter = "}>";
    $registry = Zend_Registry::getInstance();
    $registry->set(&#39;smartyview&#39;,$smarty); //smarty对象
    $registry->set(&#39;sview&#39;,$view);          
}

$this->_initSmartyView();

$view = Zend_Registry::getInstance()->get("smartyview");
//注意这是smarty对象，使用smarty的那些语法，比如 $view->assign("user","root");
$view = Zend_Registry::getInstance()->get("sview");
//这是zf的view对象，按zf中的那些方法用，不用改变。
//按这样，你如果要将以前写的代码改为用smaty，后台不用变了，只需要将视图文件改变就行了