Returning a const reference to an object instead of a copy

Question

Whilst refactoring some code I came across some getter methods that returns a std::string. Something like this for example:

class foo
{
private:
    std::st         


        

Answer 1

I normally return const& unless I can't. QBziZ gives an example of where this is the case. Of course QBziZ also claims that std::string has copy-on-write semantics which is rarely true today since COW involves a lot of overhead in a multi-threaded environment. By returning const & you put the onus on the caller to do the right thing with the string on their end. But since you are dealing with code that is already in use you probably shouldn't change it unless profiling shows that the copying of this string is causing massive performance problems. Then if you decide to change it you will need to test thouroughly to make sure you didn't break anything. Hopefully the other developers you work with don't do sketchy stuff like in Dima's answer.