如何避免在异常类中放入std::string ?

Here is my exception class:

下面是我的例外课程:

class Win32Failure : public std::exception
{
public:
    Win32Failure( char const* win32_function_name, LONG error_code );

    char const* win32_function_name() const { return win32_function_name_; }
    LONG error_code() const { return error_code_; }

    virtual char const* what() const;

private:

    std::string GetFormattedMessage() const;

    char const* win32_function_name_;
    LONG error_code_;
    std::string error_text_;
};

Win32Failure::Win32Failure( char const* win32_function_name, LONG error_code )
    : error_code_(error_code)
    , win32_function_name_(win32_function_name)
{
    std::stringstream error_msg;
    error_msg   << win32_function_name << " failed with code: "
                << error_code << " (" << GetFormattedMessage() << ")"
                ;

    error_text_ = error_msg.str();
}

std::string Win32Failure::GetFormattedMessage() const
{
    TCHAR message_buffer[1000];

    FormatMessage(
        //FORMAT_MESSAGE_ALLOCATE_BUFFER |
        FORMAT_MESSAGE_FROM_SYSTEM |
        FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL,
        error_code_,
        0, // Default language
        reinterpret_cast<LPTSTR>(&message_buffer),
        sizeof(message_buffer) / sizeof(TCHAR),
        NULL
        );

    return std::string(message_buffer);
}

char const* Win32Failure::what() const
{
    return error_text_.c_str();
}
clas