NFD » ndn-cxx

unique_ptr should be used. When the Interest is copied, simply don't copy the unique_ptr, and the second Interest instance may re-parse the Link object if necessary.

It's harmful to use shared_ptr because if someone decides to const_cast and modify the Link returned by one Interest::getLink, it would affect other instances.

I disagree. If you consider the case of violation of const access restriction, then you already have a bunch of issues with anything that return const&.

If you return a const Link&, the returned reference could outlive the referenced Link object, e.g.:

const Link& link = interest.getLink();
interest.unsetLink(); // or interest.setLink(anotherLink);
link.getDelegations(); // boom!

why not returning the shared_ptr? (this is the whole point of shared pointers... their purpose is to share ownership of an object)

One can always call .shared_from_this() if he/she needs to retain the instance. The only reason I'm against returning shared_ptr as it clutters the interface.

The issue Davide pointed is kind of possible, but I really don't want to care about this and open this can of worms (you can say the same about wireEncode(), about getName(), and about many other getters in many different classes). If one write such a statement, then his app should crash.