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 can't create a vector of const ints, and it'd be pretty useless even if you could. If i remove the second int, then everything from there on is shifted down one -- read: modified -- making it impossible to guarantee that v[5] has the same value on two different occasions.

Add to that, a const can't be assigned to after it's declared, short of casting away the constness. And if you wanna do that, why are you using const in the first place?

Answer 2

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.