Registering a class' function in LuaBridge, then calling it via a lua script?

Question

Whenever I run the program, it prints nothing to the console. This works fine if I don't use a class and just do it all in main().

The moment I put it in a class, I start having problems. What am I doing wrong?

using namespace luabridge;

myClass::myClass()
{
    lua_State* L = luaL_newstate();
    luaL_openlibs(L);
    getGlobalNamespace(L).beginClass<myClass>("myClass").addFunction("printMessage", &myClass::printMessage).endClass();
    luaL_dofile(L, "test.lua");
    lua_pcall(L, 0, 0, 0);
}

void myClass::printMessage(const std::string& s)
{
    std::cout << s << std::endl;
}

My lua script "test.lua"

I've tried

c = myClass()
c:printMessage("You can call C++ functions from Lua!")

and

myClass:printMessage("You can call C++ functions from Lua!")

and

printMessage("You can call C++ functions from Lua!")

Answer 1

There are three options to do what you want:

1. If you want to construct a myClass instance in lua, and use it like your first example, you need to also export a constructor after the beginClass:

   .addConstructor <void (*) (void)> ()

2. Construct a myClass instance in C++, and then pass it to lua using some other function. Then lua may access it like:

   myClassInstance:printMessage("Hello")

3. Make printMessage static, and export it with the following:

   .addStaticFunction("printMessage", &myClass::printMessage)

   Then you can call it in lua using:

   myClass.printMessage("Hello")

Notice the difference between . and : in the calls. . accesses like a static and : accesses like an instance.