开始救援不捕捉错误 [英] Begin Rescue not catching error

问题描述

我正在使用一些包含在开始 - 救援模块中的ruby代码，但不知何故，它仍然崩溃。

代码块如下所示：

 ＃检索邮件从服务器
 def get_messages 
 @ connection.select（'INBOX'）
 @ connection.uid_search（['ALL']）。each do | uid | 
 msg = @ connection.uid_fetch（uid，'RFC822'）。first.attr ['RFC822'] 
 begin 
 process_message（msg）
 add_to_processed_folder（uid）if @processed_folder 
 rescue 
 handle_bogus_message（msg）
 end 
＃将消息标记为已删除
 @ connection.uid_store（uid，+ FLAGS，[：Seen，... Deleted] ）
 end 
 end 
  

给定这个代码我会假设如果 process_message 或 add_to_processed_folder 无法执行，那么救援将会启动并调用 handle_bogus_message 。这就是说，我在生产环境中运行这个代码，有时当我收到一封电子邮件（这是从耙子任务运行的时候），它死了一个 SyntaxError 。

有关错误信息，请查看 http：// pastie .org / 1028479 ，而不是那个 process_message 是与上述相同的 process_message 。是否有任何原因开始 - 救援不会捕获此异常？

解决方案

rescue 没有参数只是拯救继承自 StandardError的。要拯救一个 SyntaxError 使用 rescue SyntaxError 。

拯救您将使用的所有例外 rescue Exception ，但请注意，这是一个坏主意（这就是为什么它不是默认行为 rescue ），如 here 所述和此处。特别是这部分：

拯救中断防止用户使用CTRLC退出程序。

Rescuing SignalException可防止程序对信号进行正确的响应。除了kill -9之外，它将不可用。

I'm using some ruby code wrapped in a begin - rescue block but somehow it manages to still crash.

the block of code looks like this:

# Retrieve messages from server
def get_messages
  @connection.select('INBOX')
  @connection.uid_search(['ALL']).each do |uid|
    msg = @connection.uid_fetch(uid,'RFC822').first.attr['RFC822']
    begin
      process_message(msg)
      add_to_processed_folder(uid) if @processed_folder
    rescue
       handle_bogus_message(msg)
    end
    # Mark message as deleted 
    @connection.uid_store(uid, "+FLAGS", [:Seen, :Deleted])
  end
end

Given this code i would assume that if process_message or add_to_processed_folder could not execute then rescue would kick in and call handle_bogus_message. That being said I'm running this code in a production environment and sometimes when i "get" an email message (this is run from a rake task) it dies with a SyntaxError.

For a look at the error message check out http://pastie.org/1028479 and not that process_message that it is referring to is the same process_message above. Is there any reason why begin - rescue won't catch this exception?

解决方案

rescue without a parameter just rescues exceptions that inherit from StandardError. To rescue a SyntaxError use rescue SyntaxError.

To rescue all exceptions you would use rescue Exception, but note that that's a bad idea (which is why it's not the default behavior of rescue) as explained here and here. Especially this part:

Rescuing Interrupt prevents the user from using CTRLC to exit the program.

Rescuing SignalException prevents the program from responding correctly to signals. It will be unkillable except by kill -9.

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