Question

class A
{
    ...

    public:
        shared_ptr<Logger> GimmeLogger () const
        {
            return m_logger;
        }

    private:
        shared_ptr<Logger> m_logger;
};

In class A, should GimmeLogger be const or non-const?

It would make sense to be const because it is a simple getter that doesn’t modify *this (syntactic const).

But on the other hand, it returns a non-const pointer to another object that it owns (semantically non-const).

Answer 1

If you make that non-const, then you cannot write this:

void f(const A & a)
{
    auto v = a.GimmeLogger(); //error
}

So if you want to write this; that is, if you want to call GimmeLogger on const object, then make GimmeLogger a const member function, because you cannot invoke a non-const member function, on const object. However, you can invoke a const member function, on non-const object (as well as on const object).

Inside a const member function, every member is semantically const objects. So the type of m_logger in the function becomes const share_ptr<const m_logger>. So change the return type accordingly.