试图调用带有lua错误的对象方法时，luabind中止

Question

我使用了http://www.rasterbar.com/products/luabind/docs.html#deriving-in-lua中的示例在c++中定义了一个类，我可以在lua中派生这个类：

class base
{
public:
    base(const char* s)
    { std::cout << s << "\n"; }

    virtual void f(int a)
    { std::cout << "f(" << a << ")\n"; }
};

struct base_wrapper : base, luabind::wrap_base
{
    base_wrapper(const char* s)
        : base(s)
    {}

    virtual void f(int a)
    {
        call<void>("f", a);
    }

    static void default_f(base* ptr, int a)
    {
        return ptr->base::f(a);
    }
};

...

module(L)
[
    class_<base, base_wrapper>("base")
        .def(constructor<const char*>())
        .def("f", &base::f, &base_wrapper::default_f)
];

然后我在lua中创建了一个派生类：

class 'base_derived' (base)

function base_derived:__init(str)
    base.__init(self,str)
end

function base_derived:f()
    this_function_doesnt_exist()
end

任何对'f‘的调用都应该抛出lua错误，如果我在lua中这样做，效果很好：

local x = base_derived("Test")
x:f() -- Throws "attempt to call a nil value..." error

我想这样做，但在c++中：

auto g = luabind::globals(l);
auto r = g["base_derived"];
if(r)
{
    luabind::object o = r("Test");
    auto gm = luabind::object_cast<base_wrapper*>(o);
    if(gm != nullptr)
    {
        try
        {
            luabind::call_member<void>(o,"f",5);
        }
        catch(luabind::error &e)
        {
            std::cout<<"[LUA] Error: "<<e.what()<<std::endl;
        }
    }
    o.push(l);
}

但是，‘luabind：：call_员’-调用会导致'luabind/detail/call_member.hpp‘中的中止，第258行：

// Code snippet of luabind/detail/call_member.hpp
~proxy_member_void_caller()
{
    if (m_called) return;

    m_called = true;

    // don't count the function and self-reference
    // since those will be popped by pcall
    int top = lua_gettop(L) - 2;

    // pcall will pop the function and self reference
    // and all the parameters

    push_args_from_tuple<1>::apply(L, m_args);
    if (pcall(L, boost::tuples::length<Tuple>::value + 1, 0))
    {
        assert(lua_gettop(L) == top + 1);
#ifndef LUABIND_NO_EXCEPTIONS
////////////////////////////////////////////
        throw luabind::error(L); // LINE 258
////////////////////////////////////////////
#else
        error_callback_fun e = get_error_callback();
        if (e) e(L);

        assert(0 && "the lua function threw an error and exceptions are disabled."
            "If you want to handle this error use luabind::set_error_callback()");
        std::terminate();
#endif
    }
    // pops the return values from the function
    stack_pop pop(L, lua_gettop(L) - top);
}

该行中的异常实际上不是抛出的，而是导致中止的原因。

但是，只有当lua -函数导致lua错误时，才会发生中止。如果我注释‘this_function_doesnt_exist()’-调用，lua-和c++版本都运行得很好。

为什么抛出luabind：：error(L)；会导致中止，而且即使存在潜在的lua错误，我也能做些什么来安全地从c++调用函数呢？

// Edit:这是中止时的调用堆栈(当'luabind::call_member(o，“f”，5)被调用时)：

>   vcruntime140d.dll!__CxxFrameHandler(EHExceptionRecord * pExcept, unsigned __int64 RN, _CONTEXT * pContext, _xDISPATCHER_CONTEXT * pDC) Line 213 C++
    ntdll.dll!RtlpExecuteHandlerForException()  Unknown
    ntdll.dll!RtlDispatchException()    Unknown
    ntdll.dll!KiUserExceptionDispatch() Unknown
    KernelBase.dll!RaiseException() Unknown
    vcruntime140d.dll!_CxxThrowException(void * pExceptionObject, const _s__ThrowInfo * pThrowInfo) Line 136    C++
    server.dll!luabind::detail::proxy_member_void_caller<boost::tuples::tuple<int const * __ptr64,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type> >::~proxy_member_void_caller<boost::tuples::tuple<int const * __ptr64,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type> >() Line 258    C++

这是中止消息：

​

Answer 1

见第254行：

if (pcall(L, boost::tuples::length<Tuple>::value + 1, 0))

在这里，pcall要求lua执行您的x:f(5)等效调用。显然，这段代码返回一个错误，因为pcall()返回与零不同的内容。这是预期的，因为您确实是通过调用this_function_doesnt_exist()在lua中创建一个错误。这也解释了为什么当您注释this_function_doesnt_exist()调用时不会发生中止。

然后，转到C++代码：

     throw luabind::error(L);

这个错误是从析构函数：~proxy_member_void_caller()抛出的，结果是throwing an exception from a destructor is bad practice。众所周知，luabind (see this question)可以在不抛出的情况下触发中止调用。

解决方案是将noexcept(false)添加到~proxy_member_void_caller()的签名中，如下所示：

~proxy_member_void_caller() noexcept(false)