Understanding compilation order, compilation errors, and luabind due to base class undefined

Question

How do I trace my compliation order? (So that I may re-order it)

My issue: I'm running Visual Studio 2012 writing a C++ application. I binded a scripting system, Lua, to my project using LuaBind

LuaBind hides away Lua stuff and figures out how to bind it to the Lua Language (or some magic)

I can take an object, call a function on it, and pass in a C++ object to be given to the lua script function

// ScriptComponent.h
class ScriptComponent : public Component
{
public:
    virtual void Initialize();
    virtual void Update();
protected:
    luabind::object luaDataTable;
    Entity* mOwner;

-

// ScriptComponent.cpp
void ScriptComponent::Initialize() {
    luabind::object compiledScript;
    luaL_loadfile(L, "myScript.lua");
    luabind::object compiledScript(luabind::from_stack(L, -1));
    luaDataTable = compiledScript();
    lua_pop(L, 1);
}

void ScriptComponent::Update() {
    luaDataTable["run"](mOwner); // Compiler breaks here.
    // Note: if I remove mOwner from the mix (and in the script file) everything works and runs fine.
}

Cool! But to get this to work, luabind needs to know what mOwner (Entity*) is and have ti defined. So, I define it in a different file:

// GameScriptingSystem.cpp
using namespace luabind;
module(inLuaState)
    [
        class_<GameObject>("GameObject"),
        class_<Entity, bases<GameObject> >("Entity")
            .def("DebugGetName", &Entity::DebugGetName)
    ];

The flow looks something like this:

The result:

error C2504: 'Entity' : base class undefined

Full error as requested:

...
2>  Component.cpp
2>  ScriptComponent.cpp
2>boost/type_traits/is_polymorphic.hpp(46): error C2504: 'Entity' : base class undefined
2>          boost/type_traits/is_polymorphic.hpp(62) : see reference to class template instantiation 'boost::detail::is_polymorphic_imp1<T>::d2' being compiled
2>          with
2>          [
2>              T=Entity
2>          ]
2>          boost/type_traits/is_polymorphic.hpp(97) : see reference to class template instantiation 'boost::detail::is_polymorphic_imp1<T>' being compiled
2>          with
2>          [
2>              T=Entity
2>          ]
2>          boost/type_traits/is_polymorphic.hpp(102) : see reference to class template instantiation 'boost::detail::is_polymorphic_imp<T>' being compiled
2>          with
2>          [
2>              T=Entity
2>          ]
2>          luabind/detail/make_instance.hpp(42) : see reference to class template instantiation 'boost::is_polymorphic<T>' being compiled
2>          with
2>          [
2>              T=Entity
2>          ]
2>          luabind/detail/make_instance.hpp(74) : see reference to function template instantiation 'std::pair<_Ty1,_Ty2> luabind::detail::get_dynamic_class<T>(lua_State *,T *)' being compiled
2>          with
2>          [
2>              _Ty1=luabind::detail::class_id,
2>              _Ty2=void *,
2>              T=Entity
2>          ]
2>          luabind/detail/policy.hpp(228) : see reference to function template instantiation 'void luabind::detail::make_instance<T*>(lua_State *,P)' being compiled
2>          with
2>          [
2>              T=Entity,
2>              P=Entity *
2>          ]
2>          luabind/detail/convert_to_lua.hpp(87) : see reference to function template instantiation 'void luabind::detail::pointer_converter::apply<Entity>(lua_State *,T *)' being compiled
2>          with
2>          [
2>              T=Entity
2>          ]
2>          luabind/object.hpp(1072) : see reference to function template instantiation 'void luabind::detail::convert_to_lua_p<1,Entity*,Policies>(lua_State *,const T &,const Policies &)' being compiled
2>          with
2>          [
2>              Policies=luabind::detail::null_type,
2>              T=Entity *
2>          ]
2>          luabind/object.hpp(1140) : see reference to function template instantiation 'void luabind::detail::push_args_from_tuple<Index>::apply<T0,boost::tuples::detail::map_tuple_to_cons<boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type,luabind::detail::null_type>(lua_State *,const boost::tuples::cons<HT,TT> &,const Policies &)' being compiled
2>          with
2>          [
2>              Index=1,
2>              T0=Entity *const *,
2>              HT=Entity *const *,
2>              TT=boost::tuples::detail::map_tuple_to_cons<boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type,
2>              Policies=luabind::detail::null_type
2>          ]
2>          luabind/object.hpp(1140) : see reference to function template instantiation 'void luabind::detail::push_args_from_tuple<Index>::apply<T0,boost::tuples::detail::map_tuple_to_cons<boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type,luabind::detail::null_type>(lua_State *,const boost::tuples::cons<HT,TT> &,const Policies &)' being compiled
2>          with
2>          [
2>              Index=1,
2>              T0=Entity *const *,
2>              HT=Entity *const *,
2>              TT=boost::tuples::detail::map_tuple_to_cons<boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>::type,
2>              Policies=luabind::detail::null_type
2>          ]
2>          luabind/object.hpp(1112) : see reference to function template instantiation 'luabind::adl::object luabind::adl::call_proxy<ValueWrapper,Arguments>::call<luabind::detail::null_type>(Policies *)' being compiled
2>          with
2>          [
2>              ValueWrapper=luabind::adl::index_proxy<luabind::adl::object>,
2>              Arguments=boost::tuples::tuple<Entity *const *,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>,
2>              Policies=luabind::detail::null_type
2>          ]
2>          luabind/object.hpp(1112) : see reference to function template instantiation 'luabind::adl::object luabind::adl::call_proxy<ValueWrapper,Arguments>::call<luabind::detail::null_type>(Policies *)' being compiled
2>          with
2>          [
2>              ValueWrapper=luabind::adl::index_proxy<luabind::adl::object>,
2>              Arguments=boost::tuples::tuple<Entity *const *,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>,
2>              Policies=luabind::detail::null_type
2>          ]
2>          luabind/object.hpp(1110) : while compiling class template member function 'luabind::adl::call_proxy<ValueWrapper,Arguments>::~call_proxy(void)'
2>          with
2>          [
2>              ValueWrapper=luabind::adl::index_proxy<luabind::adl::object>,
2>              Arguments=boost::tuples::tuple<Entity *const *,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>
2>          ]
2>          ..\src\Game\GameObjects\Components\ScriptComponent.cpp(75) : see reference to function template instantiation 'luabind::adl::call_proxy<ValueWrapper,Arguments>::~call_proxy(void)' being compiled
2>          with
2>          [
2>              ValueWrapper=luabind::adl::index_proxy<luabind::adl::object>,
2>              Arguments=boost::tuples::tuple<Entity *const *,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>
2>          ]
2>          ..\src\Game\GameObjects\Components\ScriptComponent.cpp(75) : see reference to class template instantiation 'luabind::adl::call_proxy<ValueWrapper,Arguments>' being compiled
2>          with
2>          [
2>              ValueWrapper=luabind::adl::index_proxy<luabind::adl::object>,
2>              Arguments=boost::tuples::tuple<Entity *const *,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type,boost::tuples::null_type>
2>          ]
2>boost/type_traits/is_polymorphic.hpp(34): error C2504: 'Entity' : base class undefined
2>          boost/type_traits/is_polymorphic.hpp(62) : see reference to class template instantiation 'boost::detail::is_polymorphic_imp1<T>::d1' being compiled
2>          with
2>          [
2>              T=Entity
2>          ]
2>  Map.cpp
2>  Generating Code...
2>  Compiling...
2>  GameScriptingSystem.cpp
2>  PoCToolsInterface.cpp
..

As far as I can tell, its due to the build order. My best guess is that Luabind does all this stuff at compiletime, and when I look at the compilation first, ScriptComponent is compiled first , GameScriptSystem is compiled after . When ScriptComponent builds, alll the luabind errors through. THEN after GameScriptSystem builds (which defines all the stuff LuaBind is complaining about)

So:

• How do I track my build order? See what files are triggering build of others, so that I may re-arrange it to my liking? (its a big project, its not as easy as looking at it for 2 seconds)

• If you know luabind, am I right about this being the issue?

Other data:

-- myScript.lua
local Cat = {}
local ticks = 0

function Cat.run(entity)
    ticks = ticks + 1
    LOG(tostring(ticks))
    LOG(entity:DebugGetName())
end

return Cat

Answer 1

No, it's not due to build order. C++ compilation units build independently. Even if the .cpp file which defines your entity has already been compiled, it won't be available automatically.

C++ never goes searching for definitions of entities. The only way to use an entity inside a compilation unit is for a declaration (depending on the usage, you might need only a forward declaration or a full definition) for that entity to exist in that compilation unit. Usually header files and #include are used to avoid code duplication.