我应该使用C ++中的异常说明符吗？ [英] Should I use an exception specifier in C++?

问题描述

在C ++中，您可以指定函数可以通过使用异常说明符来抛出异常。例如：

In C++, you can specify that a function may or may not throw an exception by using an exception specifier. For example:

void foo() throw(); // guaranteed not to throw an exception
void bar() throw(int); // may throw an exception of type int
void baz() throw(...); // may throw an exception of some unspecified type

我怀疑实际使用它们是因为

I'm doubtful about actually using them because of the following:

1. 编译器并没有严格执行异常说明符，所以好处不大。


2. 如果一个函数违反了一个异常说明符，我认为标准的行为是终止程序。


3. 在VS.Net中，它将throw（X）作为throw（...），因此遵守标准并不强。

您认为应该使用例外说明符吗？

请回答yes或no，并提供一些理由来证明您的答案。

Do you think exception specifiers should be used?
Please answer with "yes" or "no" and provide some reasons to justify your answer.

推荐答案

否。

以下是几个示例：

1. 模板代码不能用异常规范写入，

1. Template code is impossible to write with exception specifications,

template<class T>
void f( T k )
{
     T x( k );
     x.x();
}

副本可能会抛出，参数传递可能会抛出，而<$ c $

The copies might throw, the parameter passing might throw, and x() might throw some unknown exception.

异常规范倾向于禁止可扩展性。

Exception-specifications tend to prohibit extensibility.

virtual void open() throw( FileNotFound );

可能会演变为

virtual void open() throw( FileNotFound, SocketNotReady, InterprocessObjectNotImplemented, HardwareUnresponsive );

你真的可以写成

throw( ... )

旧代码

当你编写依赖另一个库的代码时，你不知道什么东西出错时可能会做什么。

When you write code which relies on another library, you don't really know what it might do when something goes horribly wrong.

int lib_f();

void g() throw( k_too_small_exception )
{ 
   int k = lib_f();
   if( k < 0 ) throw k_too_small_exception();
}

g ，当 lib_f（） throws。这是（在大多数情况下）不是你真正想要的。 std :: terminate（）不应该被调用。总是最好让应用程序崩溃与未处理的异常，您可以从中检索堆栈跟踪，而不是静静/暴力死亡。

g will terminate, when lib_f() throws. This is (in most cases) not what you really want. std::terminate() should never be called. It is always better to let the application crash with an unhandled exception, from which you can retrieve a stack-trace, than to silently/violently die.

写入

Error e = open( "bla.txt" );
if( e == FileNotFound )
    MessageUser( "File bla.txt not found" );
if( e == AccessDenied )
    MessageUser( "Failed to open bla.txt, because we don't have read rights ..." );
if( e != Success )
    MessageUser( "Failed due to some other error, error code = " + itoa( e ) );

try
{
   std::vector<TObj> k( 1000 );
   // ...
}
catch( const bad_alloc& b )
{ 
   MessageUser( "out of memory, exiting process" );
   throw;
}

库只是抛出你自己的异常，你可以使用异常规范来声明你的意图。

Nevertheless, when your library just throws your own exceptions, you can use exception specifications to state your intent.

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