I see you have three nice options here, 1. Return a shared_ptr. 2. Return a reference and throw exception for invalid indexes. 3. Return an optional. I think all three of them are nice and safe. emre

I have a class A that holds a container of objects of type B indexed by int for e.g.

Typically, I have a function of A

class A { public: const B& getB(int <index> ) const; private: std::map< int, shared_ptr<B> > listOfBs_; };

The implementation of getB could be

const B& A::getB(int <index> ) const { //what to do if index not found }

A number of solutions I think of:

1. boost::optional<const B&> getB(int <index> ) const { }

2. change signature to const B* getB(int <index> ) const

3. Define a static const B notFoundB; const B& A::getB(int <index> ) const returns notFoundB when not found and have API users compare return value with notFoundB

I suppose the cheapest in overhead/performance is 2... optional must have some time overhead?

Are there advised solutions? Favourites in terms of style?

Regards,