Creation of lua object from c++ base class

Question

I have exported from C++ into lua such base class:

 class IState { public: virtual ~IState() { } virtual void Init() = 0; virtual void Update(float dSeconds) = 0; virtual void Shutdown() = 0; virtual string Type() const = 0; }; // Wraper of state base class for lua struct IStateWrapper : IState, luabind::wrap_base { virtual void Init() { call<void>("Init"); } virtual void Update(float dSeconds) { call<void>("Update", dSeconds); } virtual void Shutdown() { call<void>("Shutdown"); } virtual string Type() const { return call<string>("Type"); } }; 

Export code:

  class_<IState, IStateWrapper>("IState") .def("Init", &IState::Init) .def("Update", &IState::Update) .def("Shutdown", &IState::Shutdown) 

The next part: I have StateManager with function: void StateManager::Push(IState*) and it's export:

        class_<StateManager>("StateManager")
            .def("Push", &StateManager::Push)

Now, I want to create object of type IState in Lua and push it into StateManager:

-- Create a table for storing object of IState cpp class
MainState = {}

-- Implementatio of IState::Init pure virtual function
function MainState:Init()
    print 'This is Init function'
end

function MainState:Update()
    print 'this is update'
end

function MainState:Shutdown()
    print 'This is shutdown'
end

state = StateManager
state.Push(MainState)

Of course, this won't work. I don't know how to say that MainState if the object of type IState:

error: No matching overload found, candidates: void Push(StateManager&,IState*)

---

UPD

    module(state, "Scene") [
        class_<StateManager>("StateManager")
            .def("Push", &StateManager::Push),

        class_<IState, IStateWrapper>("IState")
            .def("Init", &IState::Init)
            .def("Update", &IState::Update)
            .def("Shutdown", &IState::Shutdown)
    ];

    globals(state)["StateManager"] = Root::Get().GetState(); // GetState() returns pointer to obj

After example:

class 'MainState' (Scene.IState)
function MainState:__init()
    Scene.IState.__init(self, 'MainState')
end
...
state = StateManager
state:Push(MainState())

error: no static '__init' in class 'IState'

And should state = StateManager has brackets? With them there is error that no such operator.

Answer 1

You can't just throw a table at Luabind. If you intend to derive from a Luabind-defined class, you have to follow the rules of Luabind. You have to create a Lua class with Luabind's tools , derived from your IState class. That would look like this:

class 'MainState' (IState) --Assuming that you registered IState in the global table and not a Luabind module.

function MainState:__init()
    IState.__init(self, 'MainState')
end

function MainState:Init()
    print 'This is Init function'
end

function MainState:Update()
    print 'this is update'
end

function MainState:Shutdown()
    print 'This is shutdown'
end

state = StateManager()
state:Push(MainState())

Also, take note of the changes to the last two lines. Specifically, how StateManager is called , not simply set into state ). Also, how you use state: and not state. . I have no idea how this code even functioned in your example.