void doFunction(lua_State *L, int argc, t_atom *argv)
{
    lua_getglobal(L, "require");
    lua_pushstring(L, "foo"); //require("foo")
    if (lua_pcall(L, 1, LUA_MULTRET, 0))
    {
        error("error: %s", lua_tostring(L, -1));
        lua_pop(L, 1);
        return;
    }
    int top = lua_gettop(L);
    lua_getfield(L, -1, "test"); //find foo.test() function
    if (lua_type(L, -1) != LUA_TFUNCTION)
    {
        lua_pop(L, 2);
        return;
    }
    lua_newtable(L);
    for (int i = 0; i < argc; ++i) //convert array to lua table
    {
        lua_pushinteger(L, static_cast<lua_Integer>(i + 1));
        if (argv[i].a_type == A_FLOAT)
            lua_pushnumber(L, static_cast<lua_Number>(argv[i].a_w.w_float));
        else if (argv[i].a_type == A_SYMBOL)
            lua_pushstring(L, argv[i].a_w.w_symbol->s_name);
        lua_settable(L, -3);
    }
    if (lua_pcall(L, 1, LUA_MULTRET, 0)) //call foo.test() function
    {
        error("error: %s", lua_tostring(L, -1));
        lua_pop(L, 1);
        return;
    }
    if (lua_gettop(L) - top)
    {
        //do something with the returned value
    }
    lua_pop(L, 1);
}

lua_Debug ar;
 lua_getinfo(L, ">u", &ar);
 printf("%dn", ar.nparams);