Call a non-const member function from a const member function

Question

I would like to know if its possible to call a non-const member function from a const member function. In the example below First gives a compiler error. I understand why it gives an error, I would like to know if there is a way to work around it.

class Foo
{
   const int& First() const
   {
         return Second();
   }

   int& Second()
   {
        return m_bar;
   }

   int m_bar;
}

I don't really want to discuss the wisdom of doing this, I'm curious if its even possible.

Answer 1

return (const_cast<Foo*>(this))->Second();

Then cry, quietly.

Answer 2

It is possible:

const int& First() const 
{ 
    return const_cast<Foo*>(this)->Second(); 
}

int& Second() { return m_bar; }

I wouldn't recommend this; it's ugly and dangerous (any use of const_cast is dangerous).

It's better to move as much common functionality as you can into helper functions, then have your const and non-const member functions each do as little work as they need to.

In the case of a simple accessor like this, it's just as easy to return m_bar; from both of the functions as it is to call one function from the other.