C++ 中更松散的抛出说明符
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Looser Throw Specifier in C++
提问by user2824889
What does this error mean? How can I fix it? This is the header code that's causing it:
这个错误是什么意思？我该如何解决？这是导致它的标题代码：
class BadJumbleException : public exception {
public:
BadJumbleException (const string& msg); // Constructor, accepts a string as the message
string& what(); // Returns the message string
private:
string message; // Stores the exception message
};
And this is the source code:
这是源代码：
BadJumbleException::BadJumbleException (const string& m) : message(m) {}
string& BadJumbleException::what() { return message; }
EDIT: This is the error:
编辑：这是错误：
looser throw specifier for 'virtual BadJumbleException::~BadJumbleException()
'virtual BadJumbleException::~BadJumbleException() 的更宽松的抛出说明符
回答by Lightness Races in Orbit
In C++03, per §18.6.1/5, std::exceptionhas a destructor that is declared such that no exceptions can be thrown out of it (a compilation error will be caused instead).
在 C++03 中，根据 §18.6.1/5，std::exception有一个析构函数被声明为不会抛出异常（反而会导致编译错误）。
The language requires that when you derive from such a type, your own destructor must have the same restriction:
该语言要求当您从此类类型派生时，您自己的析构函数必须具有相同的限制：
virtual BadJumbleException::~BadJumbleException() throw() {}
// ^^^^^^^
This is because an overriding function may not have a looser throw specification.
这是因为覆盖函数可能没有更宽松的 throw 规范。
In C++11, std::exception::~exceptionis notmarked throw()(or noexcept) explicitly in the library code, but all destructors are noexcept(true)by default.
在C ++ 11，std::exception::~exception被未标记throw()（或noexcept）明确地在库中的代码，但是所有析构函数是noexcept(true)默认情况下。
Since that rule would include yourdestructor and allow your program to compile, this leads me to conclude that you are not reallycompiling as C++11.
由于该规则将包括您的析构函数并允许您的程序进行编译，这使我得出结论，您并没有真正按照 C++11 进行编译。
回答by Mital Vora
I was getting similar exception for one of my sample code. I tried to implement this in c++14. Here is the implementation:
我的示例代码之一遇到了类似的异常。我试图在 c++14 中实现这一点。这是实现：
class BadJumbleException : public std::exception {
public:
BadJumbleException(const std::string& m_) : msg(m_) {}
virtual ~BadJumbleException() {}
virtual const char * what() const throw() {
return msg.c_str();
}
private:
const std::string msg;
};
