PHP：追加到抛出的异常信息

Question

采取以下功能的什么我想要做的一个例子：

public function save() { 
    $this->connect('wb'); 
    try { 
     if(!$this->lock()) 
      throw new Exception("Unable to acquire configuration locks"); 
     if (!$backup = $this->backup()) 
      throw new Exception("Failed to create configuration backup"); 
     try { 
      if(!fwrite($this->_pointer, $this->dump("string"))); 
       throw new Exception("Error occured while writing to configuration"); 
      $this->unlock(); 
      $this->disconnect(); 
     } catch (Exception $e) { 
      if(rename ($backup, $this->_file)) 
       $e .= PHP_EOL."Successfully restored configuration from backup"; 
      else 
       $e .= PHP_EOL."Failed to restore configuration from backup"; 
      $this->unlock(); 
      $this->disconnect(); 
      throw $e; 
     } 
    } catch (Exception $e) { 
     echo PHP_EOL, $e->getMessage(); 
    } 
} 

我有嵌套try()和catch()语句。从最内部抛出异常并被捕获，然后执行一些函数并抛出另一个异常。注意我在哪写$e .=，我明白这是不正确的语法。我想要做的是将字符串附加到例外的$e->getMessage()。

我该怎么做呢？

Answer 1

创建您自己的异常类并创建将字符串附加到消息的方法。

<?php 
class SuperException extends Exception 
{ 
    public function AppendToMessage($msg) 
    { 
     // $this->message is inherited from Exception class, 
     // where it is protected field (member) of the class 
     $this->message .= $msg; 
    } 
} 
?> 

Answer 2

为什么不使用单独的变量来保留消息？

public function save() { 
    $this->connect('wb'); 
    $exceptionMessage = ""; 
    try { 
     if(!$this->lock()) 
      throw new Exception("Unable to acquire configuration locks"); 
     if (!$backup = $this->backup()) 
      throw new Exception("Failed to create configuration backup"); 
     try { 
      if(!fwrite($this->_pointer, $this->dump("string"))); 
       throw new Exception("Error occured while writing to configuration"); 
      $this->unlock(); 
      $this->disconnect(); 
     } catch (Exception $e) { 
      if(rename ($backup, $this->_file)) 
       $exceptionMessage .= PHP_EOL."Successfully restored configuration from backup"; 
      else 
       $exceptionMessage .= PHP_EOL."Failed to restore configuration from backup"; 
      $this->unlock(); 
      $this->disconnect(); 
      throw $e; 
     } 
    } catch (Exception $e) { 
     echo PHP_EOL. $exceptionMessage . PHP_EOL . $e->getMessage(); 
    } 
} 

Answer 3

大多数支持异常处理的面向对象的语言框架实现了对这个主题的需求。您需要了解例外不是日志发生了什么事。相反，他们在那里准确地查明错误发生的位置。

因此，不仅该语法不正确，整个想法违反了一打OOD原则。您应该引入一个记录器类，随时收集有关错误的信息，并使用例外来确定需要记录的事件。

class ErrorLogger { 

    private $log; 

    public function __construct() { 
     $this->log = array(); 
    } 

    public function log(Exception $e) { 
     array_push($this->log, $e->getMessage()); 
    } 

} 

，并进一步在代码：

$logger = new ErrorLogger(); 
try { 
    : 
} catch (Exception $e) { 
    $logger->log($e); 
}