Undefined symbol, access to a member function with a pointer C++

Question

I'd like to access to the member functions of my main class with a pointer, from a class in a lib.

I have access to the variables public in my main class. But when I try to access to the member functions (public), I have this error :

./Panda: symbol lookup error: libkoala.so: undefined symbol: _ZNK5Panda6getLOLEv

I really don't know why, maybe I don't have understand a notion in c++...

My main class:

class           Panda
{
protected:
  IAssistant*   (*external_creator)();
  IAssistant*   lib;
  void*         dlhandle;

  int           lol;
public:

  int           hello;

  Panda();
  ~Panda();

  int           getLOL() const;
};

Panda::Panda()
{
  if ((dlhandle = dlopen("libkoala.so", RTLD_LAZY)) == NULL)
    exit(-1);
  if ((external_creator = reinterpret_cast<IAssistant* (*)()>(dlsym(dlhandle, "create_assistant"))) == NULL)
    exit(-1);
  lib = external_creator();
  lol = 69;
  hello = 42;
  lib->do_something(this);
}

Panda::~Panda(){
}

int                     Panda::getLOL() const
{
  return lol;
}

The interface looks like that:

class IAssistant
{
public:
  virtual void do_something(Panda *) = 0;
};

And the class on my lib:

class Koala : public IAssistant
{
public:
  void do_something(Panda *);
};

void Koala::do_something(Panda * ptr)
{
  std::cout << ptr->hello; <========= work perfectly 
  std::cout << ptr->getLOL(); <====== doesn't work
}

extern "C"
{
        IAssistant* create_assistant()
        {
                return new Koala();
        }
}

Have you got any idea ?

Answer 1

Ok, the problem was during the compilation. After adding the flag -rdynamic, the code works perfectly.