一. lua调用C++
在lua中是以函数指针的形式调用函数, 并且所有的函数指针都必须满足如下此种类型:
typedef int (*lua_CFunction) (lua_State *L);
也就是说, 偶们在C++中定义函数时必须以lua_State为参数, 以int为返回值才能被Lua所调用. 但是不要忘记了, 偶们的lua_State是支持栈的, 所以通过栈可以传递无穷个参数, 大小只受内存大小限制. 而返回的int值也只是指返回值的个数真正的返回值都存储在lua_State的栈中. 偶们通常的做法是做一个wrapper, 把所有需要调用的函数都wrap一下, 这样就可以调用任意的函数了.
#include<iostream>
using namespace std;
#include<stdio.h>
extern "C" {
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
}
//#pragma comment(lib, "lua5.1.lib")
lua_State* L;
static int average(lua_State *L)
{//返回栈中元素的个数int n = lua_gettop(L);double sum = 0;int i;for (i = 1; i <= n; i++){if (!lua_isnumber(L, i)) {lua_pushstring(L, "Incorrect argument to 'average'");lua_error(L);}sum += lua_tonumber(L, i);}/* push the average */lua_pushnumber(L, sum / n);/* push the sum */lua_pushnumber(L, sum);/* return the number of results */return 2;
}
int main (int argc,char*argv[])
{/* initialize Lua */L = lua_open();/* load Lua libraries */luaL_openlibs(L);/* register our function */lua_register(L, "average", average);/* run the script */luaL_dofile(L, "e15.lua");lua_getglobal(L,"avg");cout<<"avg is:"<<lua_tointeger(L,-1)<<endl;lua_pop(L,1);lua_getglobal(L,"sum");cout<<"sum is:"<<lua_tointeger(L,-1)<<endl;/* cleanup Lua */lua_close(L);return 0;
}
//程序
//*lua_gettop()的作用是返回栈顶元素的序号. 由于Lua的栈是从1开始编号的,
// 所以栈顶元素的序号也相当于栈中的元素个数. 在这里, 栈中元素的个数就
// 是传入的参数个数.
//* for循环计算所有传入参数的总和. 这里用到了数值转换lua_tonumber().
//* 然后偶们用lua_pushnumber()把平均值和总和push到栈中.
//* 最后, 偶们返回2, 表示有两个返回值.
//* 虽然在C++中定义了average()函数, 但Lua程序并不知道, 所以需
// 要在main函数中加入
// // register our function
// lua_register(L, "average", average);
// 这两行的作用就是告诉e15.lua有average()这样一个函数.
//* 这个程序可以存成cpp也可以存成c, 如果以.c为扩展名就不需要加extern "C"
//
//编译的方法偶们上次说过了, 方法相同.
//e15.lua执行的方法只能用上例中的C++中执行, 而不能用命令行方式执行.*/
目标：
- 独立，无需第三方库依赖
- 小巧，仅提供大多数场景的功能需求
- 易用，接口简单明确
- 方便，提供完备的错误信息
目录结构：
state.hpp—对lua_state封装，支持对内存定制
reference.hpp—对lua的function、string、table引用，提高性能会用到
module.hpp--支持类似C++中namespace功能，以table方式实现
lua_reg.hpp--头文件包含
iterator.hpp--对不定参数的迭代
execute.hpp--执行lua文件，对lua_pcall封装，支持错误处理
error.hpp--错误处理，提供fatal_error与parameter_error，支持对堆栈内容的解析
converter.hpp--C++数据与lua数据的转换，默认支持C++原生类型、std::string\std::pair\std::tuple\std::map\std::vector
config.hpp--这个没什么好说的
class.hpp--对C++类的支持
call.hpp--lua_pcall封装，C++调用lua函数，支持错误处理
优势：
1. 可定制内存分配器，满足allocate、deallocate即可，默认使用std::allocator
2. 错误信息丰富，堆栈、参数列表、详情
3. 参数转换可扩展，采用模板偏特化方式实现，默认有std::vector\std::pair\std::tuple\std::map\std::string等STL容器类型
4. 支持lua中namespace（即module），采用table实现
实现机制：
1. lua参数与C++参数转换
<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1: </span><span class="kwrd">template</span> < <span class="kwrd">typename</span> T, <span class="kwrd">typename</span> EnableT = <span class="kwrd">void</span> ></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> <span class="kwrd">struct</span> convertion_t;</span>当需要对lua与C++参数进行转换时，请考虑片特化此类，如void*对应lightuserdata
<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> <span class="kwrd">template</span> < ></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> <span class="kwrd">struct</span> convertion_t<<span class="kwrd">void</span> *></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> <span class="kwrd">static</span> <span class="kwrd">void</span> * from(state_t &state, <span class="kwrd">int</span> index)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum5" class="lnum"> 5:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum6" class="lnum"> 6:</span> LUAREG_ERROR(lua_islightuserdata(state, index) != 0, LUA_TLIGHTUSERDATA, index);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum7" class="lnum"> 7:</span> </span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum8" class="lnum"> 8:</span> <span class="kwrd">return</span> ::lua_touserdata(state, index);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum9" class="lnum"> 9:</span> }</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum10" class="lnum"> 10:</span> </span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum11" class="lnum"> 11:</span> <span class="kwrd">static</span> std::uint32_t to(state_t &state, <span class="kwrd">void</span> *val)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum12" class="lnum"> 12:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum13" class="lnum"> 13:</span> <span class="kwrd">if</span>( val != nullptr )</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum14" class="lnum"> 14:</span> ::lua_pushlightuserdata(state, val);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum15" class="lnum"> 15:</span> <span class="kwrd">else</span></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum16" class="lnum"> 16:</span> ::lua_pushnil(state);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum17" class="lnum"> 17:</span> </span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum18" class="lnum"> 18:</span> <span class="kwrd">return</span> 1;</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum19" class="lnum"> 19:</span> }</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum20" class="lnum"> 20:</span> };</span>
2. C++函数与lua函数对应关系
当需要把C++函数注册到lua，如
<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> <span class="kwrd">int</span> test2(<span class="kwrd">int</span> n, <span class="kwrd">double</span> d, <span class="kwrd">const</span> std::string &msg)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> <span class="kwrd">return</span> 10;</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> }</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> luareg::module(state, <span class="str">"cpp"</span>)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> << lua::def(<span class="str">"test2"</span>, &test2);</span>在lua::def函数里，首先会推导test2的函数签名
<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> <span class="kwrd">template</span> < <span class="kwrd">typename</span> R, <span class="kwrd">typename</span> ...Args ></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> <span class="kwrd">inline</span> details::free_function_t<R, Args...> def(<span class="kwrd">const</span> <span class="kwrd">char</span> *name, R(*func)(Args...))</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> <span class="kwrd">return</span> details::free_function_t<R, Args...>(name, func);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum5" class="lnum"> 5:</span> }</span>根据模版参数，得到返回值类型，参数类型，构建一个free_function_t对象<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> <span class="kwrd">template</span> < <span class="kwrd">typename</span> R, <span class="kwrd">typename</span> ...Args ></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> <span class="kwrd">struct</span> free_function_t</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> <span class="kwrd">const</span> <span class="kwrd">char</span> *name_;</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum5" class="lnum"> 5:</span> </span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum6" class="lnum"> 6:</span> <span class="kwrd">typedef</span> R(*function_t)(Args...);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum7" class="lnum"> 7:</span> function_t function_;</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum8" class="lnum"> 8:</span> </span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum9" class="lnum"> 9:</span> free_function_t(<span class="kwrd">const</span> <span class="kwrd">char</span> *name, function_t func)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum10" class="lnum"> 10:</span> : name_(name)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum11" class="lnum"> 11:</span> , function_(func)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum12" class="lnum"> 12:</span> {}</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum13" class="lnum"> 13:</span> };</span>free_function_t对象保存注册名及当前函数指针，通过operator<<操作符把这个free_function_t匿名对象给module的临时匿名对象<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> <span class="kwrd">inline</span> module_t module(state_t &state, <span class="kwrd">const</span> <span class="kwrd">char</span> *name = nullptr)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> <span class="kwrd">if</span>( name )</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> assert(std::strlen(name) != 0);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum5" class="lnum"> 5:</span> <span class="kwrd">return</span> module_t(state, name);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum6" class="lnum"> 6:</span> }</span>在module里，提供了operator<<操作符重载<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> <span class="kwrd">template</span> < <span class="kwrd">typename</span> R, <span class="kwrd">typename</span> ...Args ></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> module_t &<span class="kwrd">operator</span><<(<span class="kwrd">const</span> details::free_function_t<R, Args...> &func)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> <span class="kwrd">auto</span> lambda = [](lua_State *l)-><span class="kwrd">int</span></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum5" class="lnum"> 5:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum6" class="lnum"> 6:</span> state_t state(l);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum7" class="lnum"> 7:</span> <span class="kwrd">typedef</span> <span class="kwrd">typename</span> details::free_function_t<R, Args...>::function_t function_t;</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum8" class="lnum"> 8:</span> <span class="kwrd">auto</span> func = <span class="kwrd">static_cast</span><function_t>(::lua_touserdata(state, lua_upvalueindex(1)));</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum9" class="lnum"> 9:</span> </span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum10" class="lnum"> 10:</span> <span class="kwrd">return</span> details::call(state, func);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum11" class="lnum"> 11:</span> };</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum12" class="lnum"> 12:</span> </span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum13" class="lnum"> 13:</span> ::lua_pushlightuserdata(state_, func.function_);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum14" class="lnum"> 14:</span> ::lua_pushcclosure(state_, lambda, 1);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum15" class="lnum"> 15:</span> ::lua_setfield(state_, -2, func.name_);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum16" class="lnum"> 16:</span> </span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum17" class="lnum"> 17:</span> <span class="kwrd">return</span> *<span class="kwrd">this</span>;</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum18" class="lnum"> 18:</span> }</span>通过把free_function_t对象的function_\name_注册到lua，这里使用了lua_pushccloure这个API，利用upvalue保存了这个注册函数的指针。这里的lambda是Lua_CFunction的原型，一旦lua调用了这个函数，就会回到这个lambda函数体中，再把函数指针取出来进行调用即可。
再来看看这个details::call
<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> <span class="kwrd">template</span> < <span class="kwrd">typename</span> R, <span class="kwrd">typename</span> ...Args ></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> std::int32_t call(state_t &state, R(*handler)(Args...),</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> <span class="kwrd">typename</span> std::enable_if<!std::is_same<R, <span class="kwrd">void</span>>::value>::type * = nullptr)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum5" class="lnum"> 5:</span> <span class="kwrd">return</span> convertion_t<R>::to(state, call_impl(state, make_obj(handler), 0));</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum6" class="lnum"> 6:</span> }</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> <span class="kwrd">template</span> < <span class="kwrd">typename</span> R, <span class="kwrd">typename</span> ...Args ></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> std::int32_t call(state_t &state, R(*handler)(Args...),</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> <span class="kwrd">typename</span> std::enable_if<std::is_same<R, <span class="kwrd">void</span>>::value>::type * = nullptr)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum5" class="lnum"> 5:</span> call_impl(state, make_obj(handler), 0);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum6" class="lnum"> 6:</span> </span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum7" class="lnum"> 7:</span> <span class="kwrd">return</span> 0;</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum8" class="lnum"> 8:</span> }</span>返回值代表返回多少个数据到lua，通过convertion来完成。这里的enable_if来决断调用的C++函数返回值是否为void，如果为void则返回0个参数到lua。
解析就写到这儿吧，至于call_impl和make_obj请大家自己看源码吧，如果有什么不明白的，请加群探讨165666547
使用示例:
1. 对lua内存定制，只需要满足allocate、deallocate接口
<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> std::allocator<<span class="kwrd">char</span>> std_allocator;</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> luareg::state_t state(std_allocator);</span><span style="font-family: 'Microsoft YaHei UI';"></span>2. 注册自由函数
<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> luareg::module(state, <span class="str">"cpp"</span>)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> << lua::def(<span class="str">"test0"</span>, &test0)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> << lua::def(<span class="str">"test1"</span>, &test1)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> << lua::def(<span class="str">"test2"</span>, &test2)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum5" class="lnum"> 5:</span> << lua::def(<span class="str">"test3"</span>, &test3)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum6" class="lnum"> 6:</span> << lua::def(<span class="str">"test4"</span>, &test4)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum7" class="lnum"> 7:</span> << lua::def(<span class="str">"test5"</span>, &test5)</span>当然，也可以注册类的成员函数，但是并不是由lua提供的userdata作为对象指针，而是由C++保存的指针<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> lua::def(<span class="str">"test6"</span>, &t, &test_t::test6);</span>
3. 注册类<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> luareg::module(state, <span class="str">"cpp"</span>)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> [</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> luareg::class_t<foo_t>(state, <span class="str">"foo_t"</span>)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> << luareg::constructor<<span class="kwrd">int</span>>()</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum5" class="lnum"> 5:</span> << luareg::destructor()</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum6" class="lnum"> 6:</span> << luareg::def(<span class="str">"add"</span>, &foo_t::add)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum7" class="lnum"> 7:</span> << luareg::def(<span class="str">"get"</span>, &foo_t::get)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum8" class="lnum"> 8:</span> << luareg::def(<span class="str">"get_pointer"</span>, &foo_t::get_pointer)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum9" class="lnum"> 9:</span> << luareg::def(<span class="str">"get_base"</span>, &foo_t::get_base)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum10" class="lnum"> 10:</span> ]</span><span style="font-family: 'Microsoft YaHei UI';">需要注意的是constructor与destructor都不是必须的，如果没有，则采用默认。是不是很像luabind的语法呢？</span>
<span style="font-family: 'Microsoft YaHei UI';">4. 执行lua文件</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> lua::execute(state, <span class="str">"test.lua"</span>);</span>
5. 执行lua的一个函数<span style="font-family: 'Microsoft YaHei UI';"><span id="lnum1" class="lnum"> 1:</span> <span class="kwrd">try</span></span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum2" class="lnum"> 2:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum3" class="lnum"> 3:</span> lua::execute(state, <span class="str">"test2.lua"</span>);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum4" class="lnum"> 4:</span> std::pair<<span class="kwrd">int</span>, std::string> n = lua::call(state, <span class="str">"test_call"</span>, 1, <span class="str">"haha"</span>, 10.2, false);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum5" class="lnum"> 5:</span> </span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum6" class="lnum"> 6:</span> <span class="kwrd">auto</span> val = std::make_pair(<span class="str">"test abc"</span>, 10.2);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum7" class="lnum"> 7:</span> lua::call(state, <span class="str">"test_call2"</span>, 1, <span class="str">"haha"</span>, val);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum8" class="lnum"> 8:</span> }</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum9" class="lnum"> 9:</span> <span class="kwrd">catch</span>(<span class="kwrd">const</span> luareg::fatal_error_t &e)</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum10" class="lnum"> 10:</span> {</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum11" class="lnum"> 11:</span> std::cout << e.what() << std::endl;</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum12" class="lnum"> 12:</span> e.dump(std::cout);</span><span style="font-family: 'Microsoft YaHei UI';"><span id="lnum13" class="lnum"> 13:</span> }</span>执行lua的test_call函数，返回两个值，因为lua可以返回多值，所以在C++中可以采用tuple或者pair来接收。其中，错误均已throw异常来处理，当然，debug的时候会有assert及堆栈信息和参数信息。
局限性：
- 对注册函数均已upvalue的方式来保存，限制了C++导出到lua函数个数（upvalue最大个数为255），不过，我认为这已足够，如果要导出很多接口道lua，那已经是不正常的了
- 与luabind比起，某些功能不支持（函数重载、导出变量等）
后记：
本框架大量使用C++11特性，使实现非常优雅的解决许多问题，比如lambda、variadic template、auto、decltype等等，所以，需要理解C++11，如果你有可能，请加入我们的C++11讨论群165666547。
github：https://github.com/chenyu2202863/lua_reg
