Can I use const in vectors to allow adding elements, but not modifications to the already added?

Question

My comments on this answer got me thinking about the issues of constness and sorting. I played around a bit and reduced my issues to the fact that this code:

Answer 1

You could derive a class const_vector from std::vector that overloads any method that returns a reference, and make it return a const reference instead. To do your sort, downcast back to std::vector.