C中的内联throw()方法

发布时间：2020-12-16 03:36:10 所属栏目：百科来源：网络整理

导读：我试图定义一个非常简单的异常类.因为它非常简单,我只想将它保存在.h文件中,但编译器不喜欢throw().代码： #include exception#include stringclass PricingException : public virtual std::exception{private: std::string msg;public: PricingException(s

我试图定义一个非常简单的异常类.因为它非常简单,我只想将它保存在.h文件中,但编译器不喜欢throw().代码：

#include <exception>
#include <string>

class PricingException : public virtual std::exception
{
private:
    std::string msg;
public:
        PricingException(std::string message) : msg(message) {}
        const char* what() const throw() { return msg.c_str(); }
        ~PricingException() throw() {}
};

GCC给出以下错误：

/home/ga/dev/CppGroup/MonteCarlo/PricingException.h:13: error: expected unqualified-id before ‘{’ token
/home/ga/dev/CppGroup/MonteCarlo/PricingException.h:14: error: expected unqualified-id before ‘{’ token

对于带有throw()的行.知道怎么解决吗？

编辑

我试图删除有问题的方法的主体,即

virtual ~PricingException() throw();// {}

现在我得到更奇怪的错误信息：

/home/ga/dev/CppGroup/MonteCarlo/PricingException.h:14: error: looser throw specifier for ‘virtual PricingException::~PricingException()’
/usr/include/c++/4.5/exception:65: error:   overriding ‘virtual std::exception::~exception() throw ()’

它只是忽略了我的throw说明符！

解决方法

尝试使用C 0x语法,g 4.5可能已经足够支持它了：

const char* what() const noexcept { return msg.c_str(); }

但是,这应该不重要(来自3242草案,[除了.spec]部分的措辞：

Two exception-specifications are compatible if:

both are non-throwing (see below),regardless of their form,

both have the form noexcept(constant-expression) and the constant-expressions are equivalent,

one exception-specification is a noexcept-specification allowing all exceptions and the other is of the form throw(type-id-list),or

both are dynamic-exception-specifications that have the same set of adjusted types.

If a virtual function has an exception-specification,all declarations,including the definition,of any function that overrides that virtual function in any derived class shall only allow exceptions that are allowed by the exception-specification of the base class virtual function.

A function with no exception-specification or with an exception-specification of the form noexcept(constant-expression) where the constant-expression yields false allows all exceptions. An exception-specification is
non-throwing if it is of the form throw(),noexcept,or noexcept(constant-expression) where the constant-expression yields true. A function with a non-throwing exception-specification does not allow any exceptions.

因此,尝试更新的g版本,这些更改可能会更完整地实现.

（编辑：李大同）

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