在C中存储对lua函数的引用

我有一个用C++实现的基本事件处理程序。我的应用程序中还有一个嵌入的Lua解释器，我需要它与事件管理器交互。最终目标是能够有一个事件处理程序，当事件被触发时，它将同时执行c++和Lua函数。

我的问题是，我无法想出一种简单的方法来在C++代码中存储对lua函数的引用。我知道如何从c执行Lua函数(使用lua_getglobal和lua_pcall)，但我更喜欢存储对函数本身的引用，这样我就可以将Lua函数直接传递给registerListener

注意假设所有Lua监听器的用户数据都是NULL是可以接受的。

这是我的代码：

EventManager.h

#include <string>
#include <map>
#include <vector>
using namespace std;
typedef void (*fptr)(const void* userdata, va_list args);
typedef pair<fptr, void*> Listener;
typedef map<string, vector<Listener> > CallbackMap;
class EventManager {
private:
friend ostream& operator<<(ostream& out, const EventManager& r);
CallbackMap callbacks;
static EventManager* emInstance;
EventManager() {
callbacks = CallbackMap();
}
~EventManager() {
}
public:
static EventManager* Instance();
bool RegisterEvent(string const& name);
void RegisterListener(string const &event_name, fptr callback,
void* userdata);
bool FireEvent(string name, ...);
};
inline ostream& operator<<(ostream& out, const EventManager& em) {
return out << "EventManager: " << em.callbacks.size() << " registered event"
<< (em.callbacks.size() == 1 ? "" : "s");
}

EventManager.cpp

#include <cstdarg>
#include <iostream>
#include <string>
#include "EventManager.h"
using namespace std;
EventManager* EventManager::emInstance = NULL;
EventManager* EventManager::Instance() {
if (!emInstance) {
emInstance = new EventManager;
}
return emInstance;
}
bool EventManager::RegisterEvent(string const& name) {
if (!callbacks.count(name)) {
callbacks[name] = vector<Listener>();
return true;
}
return false;
}
void EventManager::RegisterListener(string const &event_name, fptr callback,
void* userdata) {
RegisterEvent(event_name);
callbacks[event_name].push_back(Listener(callback, userdata));
}
bool EventManager::FireEvent(string name, ...) {
map<string, vector<Listener> >::iterator event_callbacks =
callbacks.find(name);
if (event_callbacks == callbacks.end()) {
return false;
}
for (vector<Listener>::iterator cb =
event_callbacks->second.begin();
cb != event_callbacks->second.end(); ++cb) {
va_list args;
va_start(args, NULL);
(*cb->first)(cb->second, args);
va_end(args);
}
return true;
}

luaw_eventmanager.h

#pragma once
#ifndef LUAW_EVENT_H
#define LUAW_EVENT_H
#include "EventManager.h"
extern "C" {
#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>
void luaw_eventmanager_push(lua_State* L, EventManager* em);
int luaopen_weventmanager(lua_State* L);
}
#endif

luaw_eventmanager.cpp

#include <assert.h>
#include <stdio.h>
#include <sstream>
#include <iostream>
#include "luaw_eventmanager.h"
using namespace std;
static int
luaw_eventmanager_registerevent(lua_State* L)
{
int nargs = lua_gettop(L);
if (nargs != 2) {
return 0;
}
stringstream ss;
ss << luaL_checkstring(L, 2);
EventManager::Instance()->RegisterEvent(ss.str());
return 1;
}
static int
luaw_eventmanager_registerlistener(lua_State* L)
{
return 1;
}
static int
luaw_eventmanager_fireevent(lua_State* L)
{
return 1;
}
static int
luaw_eventmanager_tostring(lua_State* L)
{
stringstream ss;
ss << *EventManager::Instance();
lua_pushstring(L, &ss.str()[0]);
return 1;
}
static const struct luaL_Reg luaw_eventmanager_m [] = {
{"registerEvent", luaw_eventmanager_registerevent},
{"registerListener", luaw_eventmanager_registerlistener},
{"fireEvent", luaw_eventmanager_fireevent},
{"__tostring", luaw_eventmanager_tostring},
{NULL, NULL}
};
void 
luaw_eventmanager_push(lua_State* L, EventManager* em)
{
EventManager** emUserdata = (EventManager**)lua_newuserdata(L, sizeof(EventManager*));
*emUserdata = em;
luaL_getmetatable(L, "WEAVE.mEventManager");
lua_setmetatable(L, -2);
}
int 
luaopen_weventmanager(lua_State* L)
{
luaL_newmetatable(L, "WEAVE.mEventManager");
lua_pushvalue(L, -1);
lua_setfield(L, -2, "__index");
luaL_register(L, NULL, luaw_eventmanager_m);
assert(!lua_isnil(L, -1));
return 1;
}