挺难懂的
下面这段代码如何理解呢，最好在关节点上给与解释
* 行为模型实例<br /> *<br /> * @param string $model 模型名称<br /> * @return obj 对象形式的返回结果<br /> */<br />function Logic($model = null, $base_path = null){<br /> static $_cache = array();<br /> $cache_key = $model.'.'.$base_path;<br /> if (!is_null($model) && isset($_cache[$cache_key])) return $_cache[$cache_key];<br /> $base_path = $base_path == null ? BASE_DATA_PATH : $base_path;<br /> $file_name = $base_path.'/logic/'.$model.'.logic.php';<br /> $class_name = $model.'Logic';<br /> if (!file_exists($file_name)){<br /> return $_cache[$cache_key] = new Model($model);<br /> }else{<br /> require_once($file_name);<br /> if (!class_exists($class_name)){<br /> $error = 'Logic Error: Class '.$class_name.' is not exists!';<br /> throw_exception($error);<br /> }else{<br /> return $_cache[$cache_key] = new $class_name();<br /> }<br /> }<br />}<br />function Logic($model = null, $base_path = null){<br /> //定义静态变量<br /> static $_cache = array();<br /> //定义缓存key值<br /> $cache_key = $model.'.'.$base_path;<br /> //若是静态变量中有这个模型的实例就直接返回<br /> if (!is_null($model) && isset($_cache[$cache_key])) return $_cache[$cache_key];<br /> //组织类文件路径<br /> $base_path = $base_path == null ? BASE_DATA_PATH : $base_path;<br /> $file_name = $base_path.'/logic/'.$model.'.logic.php';<br /> $class_name = $model.'Logic';<br /> //类文件是否存在<br /> if (!file_exists($file_name)){<br /> //不存在就实例一个model<br /> return $_cache[$cache_key] = new Model($model);<br /> }else{<br /> //存在就引入<br /> require_once($file_name);<br /> //判断是否存在 该类<br /> if (!class_exists($class_name)){<br /> //不存在就抛出异常<br /> $error = 'Logic Error: Class '.$class_name.' is not exists!';<br /> throw_exception($error);<br /> }else{<br /> //存在就实例化它，存入静态数组中并返回<br /> return $_cache[$cache_key] = new $class_name();<br /> }<br /> }<br />}<br />
