C++ call reference function from a const pointer

Question

I have a class with this function

class InputState
{
   public:
     key_map const & GetKeyMap();
}

then I have a const pointer:

InputState const * m_pInput;

How can I call that function from m_pInput ?

Answer 1

If your function indeed does not modify the object itself, mark it as const :

 key_map const & GetKeyMap() const;

If it does modify, do not call it from a const pointer (or, well, use const_cast if absolutely needed).

Answer 2

If: your member function doesn't alter the state of the object you add to it the const qualifier:

key_map const & GetKeyMap() const;

Else: use const_cast , which I don't recommend since it would break explicitly the const enss of your pointer, that might be for a reason in the first place:

const_cast<InputState*>(m_pInput)->GetKeyMap();