Question

I’m using VS2010.
In the constructor of my non-compyable Scene class I have :

auto& character_mgr = CharacterManager::Instance();
    character_mgr.initialize();
character_mgr.add_observer(  std::bind( &Scene::on_character_event, *this, std::placeholders::_1, std::placeholders::_2 ) );

Here add_observer is defined as :

void add_observer( Observer observer ){ ... }

with Observer defined as :

typedef std::function< void ( CharacterEvent, const Character& ) > Observer;

The problem is that the compiler tells me there is an attempt to copy my Scene, that I provided in the bind using *this, thinking it would keep a reference on it, not trying to copy it when I copy the functor generated by the binding.

1. Why does it try to copy my object? Is it normal?
2. How should I do to avoid the copy while providing the member function of my object?

Answer 1

1. It’s the default behaviour.
2. To pass by reference, try using std::ref .