为什么C ++ 0x的`noexcept`被动态检查？ [英] Why is C++0x's `noexcept` checked dynamically?

问题描述

我很好奇 noexcept 背后的理由/papers/2010/n3092.pdf\"> C++0x FCD 。 throw（X）已被弃用，但 noexcept 似乎也做同样的事情。有没有理由 noexcept 在编译时没有检查？看起来，如果这些函数被静态检查，他们只在 try 块中调用抛出函数会更好。

I am curious about the rationale behind noexcept in the C++0x FCD. throw(X) was deprecated, but noexcept seems to do the same thing. Is there a reason that noexcept isn't checked at compile time? It seems that it would be better if these functions were checked statically that they only called throwing functions within a try block.

推荐答案

如果我记得throw已经被弃用，因为没有办法指定模板函数可以抛出的所有异常。即使对于非模板函数，您将需要throw子句，因为您已经添加了一些跟踪。

If I remember throw has been deprecated because there is no way to specify all the exceptions a template function can throw. Even for non-template functions you will need the throw clause because you have added some traces.

另一方面，编译器可以优化不会抛出异常的代码。请参阅关于noexcept的辩论，第一部分（以及 II 和III ）进行详细讨论。主要点似乎是：

On the other hand the compiler can optimize code that doesn't throw exceptions. See "The Debate on noexcept, Part I" (along with parts II and III) for a detailed discussion. The main point seems to be:

过去二十年的丰富经验表明，在实践中，只有两种形式的异常规范是有用的：

The vast experience of the last two decades shows that in practice, only two forms of exceptions specifications are useful:

• 缺少明确的异常规范，指定一个可以引发任何类型异常的函数：

• The lack of an overt exception specification, which designates a function that can throw any type of exception:

int func(); //might throw any exception

这样的函数可以由throw（）规范指示：

A function that never throws. Such a function can be indicated by a throw() specification:

int add(int, int) throw(); //should never throw any exception

这篇关于为什么C ++ 0x的`noexcept`被动态检查？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！