单个“抛出”是什么？声明呢？ [英] What does a single "throw;" statement do?

问题描述

这些天，我一直在阅读很多 C ++ FAQ ，特别是< a href =http://www.parashift.com/c++-faq-lite/exceptions.html =noreferrer>此页面。

阅读本节我发现一个技巧，作者称之为异常调度程序，允许某人将其所有的异常处理组合在一个方便的功能中：

  void handleException（）
 {
 try {
 throw; //？ 
} 
 catch（MyException& e）{
 //...code处理MyException ... 
} 
 catch（YourException& e）{
 //...code来处理YourException ... 
} 
} 
 
 void f（）
 {
 try {
 // ...可能会抛出... 
} 
 catch（...）{
 handleException（）; 
} 
} 
  

令人困扰的是单个 throw; 语句：如果你考虑给定的例子，那么确定，它是显而易见的：它重新抛出首先在 f（）并再次处理它。

但是如果我直接调用 handleException（）从 catch（）子句执行它？有没有指定的行为？

除了奖励积分，还有其他奇怪（可能不是好的话）使用 throw 你知道吗？

谢谢。

解决方案>

如果你自己做一个 throw; ，那么它不会被重新抛出，而程序会突然结束。 （更具体地说， terminate（）被调用。）

注意throw;是重新抛出当前异常的唯一安全方式 - 它不等于

catch（exception const& e）{throw e; }

These days, I have been reading a lot the C++ F.A.Q and especially this page.

Reading through the section I discovered a "technique" that the author calls "exception dispatcher" that allows someone to group all his exception handling in one handy function:

void handleException()
{
  try {
    throw; // ?!
  }
  catch (MyException& e) {
    //...code to handle MyException...
  }
  catch (YourException& e) {
    //...code to handle YourException...
  }
}

void f()
{
  try {
    //...something that might throw...
  }
  catch (...) {
    handleException();
  }
}

What bothers me is the single throw; statement: if you consider the given example then sure, it is obvious what it does: it rethrows the exception first caught in f() and deals with it again.

But what if I call handleException() on its own, directly, without doing it from a catch() clause ? Is there any specified behavior ?

Additionally for bonus points, is there any other "weird" (probably not the good word) use of throw that you know of ?

Thank you.

解决方案

If you do a throw; on its own, and there isn't a current exception for it to rethrow, then the program ends abruptly. (More specifically, terminate() is called.)

Note that throw; is the only safe way to re-throw the current exception - it's not equivalent to

catch (exception const & e) { throw e; }

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