使用luac API从表中提取用户数据

我使用luacapi来循环表中的变量，比如这个

lua脚本：

array = {0,1,2,3}

lua c api

lua_getglobal(l, "array");
if(lua_isnil(l, -1)) {
}
lua_pushnil(l);
while(lua_next(l, -2)) {
    int value=(int)lua_tonumber(l, -1);
    printf("%d n",value);
    lua_pop(l, 1);
}

我可以得到的结果

01.2.3

然后我想在表中放入一些用户数据对象然后在c api 中循环它们

lua脚本

foo0 = Foo.new("fred0")
foo1 = Foo.new("fred0")
foo2 = Foo.new("fred0")
foo3 = Foo.new("fred0")
array = {foo0,foo1,foo2,foo3}

lua c api

extern "C"
{
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
}
#include <iostream>
#include <sstream>
#include <vector>
class Foo
{
public:
    Foo(const std::string & name) : name(name)
    {
        std::cout << "Foo is born" << std::endl;
    }
    std::string Add(int a, int b)
    {
        std::stringstream ss;
        ss << name << ": " << a << " + " << b << " = " << (a+b);
        return ss.str();
    }
    ~Foo()
    {
        std::cout << "Foo is gone" << std::endl;
    }
    std::string name;
};

int l_Foo_constructor(lua_State * l)
{
    const char * name = luaL_checkstring(l, 1);
    Foo ** udata = (Foo **)lua_newuserdata(l, sizeof(Foo *));
    *udata = new Foo(name);
    luaL_getmetatable(l, "luaL_Foo");
    lua_setmetatable(l, -2);
    return 1;
}


Foo * l_CheckFoo(lua_State * l, int n)
{
    return *(Foo **)luaL_checkudata(l, n, "luaL_Foo");
}
int l_Foo_add(lua_State * l)
{
    return 1;
}
int l_Foo_destructor(lua_State * l)
{
    Foo * foo = l_CheckFoo(l, 1);
    delete foo;
    return 0;
}
void RegisterFoo(lua_State * l)
{
    luaL_Reg sFooRegs[] =
    {
        { "new", l_Foo_constructor },
        { "add", l_Foo_add },
        { "__gc", l_Foo_destructor },
        { NULL, NULL }
    };
    luaL_newmetatable(l, "luaL_Foo");
    luaL_register(l, NULL, sFooRegs);
    lua_pushvalue(l, -1);
    lua_setfield(l, -1, "__index");
    lua_setglobal(l, "Foo");
}
int main()
{
    lua_State * l = luaL_newstate();
    luaL_openlibs(l);
    RegisterFoo(l);
    int erred = luaL_dofile(l,"/Volumes/Work/CODE/Test/testStatic/testStatic/kami.txt");
    if(erred)
        std::cout << "Lua error: " << luaL_checkstring(l, -1) << std::endl;

    lua_getglobal(l, "array");
    if(lua_isnil(l, -1)) {
        //return std::vector();
    }
    lua_pushnil(l);
    std::vector<Foo *> v;
    while(lua_next(l, -2)) {

        Foo * foo = l_CheckFoo(l, -1);//this line do not work
        //
        //
        //
        //
        //I don't know how to do it here.
        //
        //
        //
        //
        //v.push_back(foo);
        lua_pop(l, 1);
    }

//    for (Foo* theValue:v)
//    {
//        printf("==>%s",theValue->name.c_str());
//    }
    lua_close(l);
    return 0;
}

如何从表中提取用户数据？请帮帮我，谢谢。