Is there any benefit to using virtual_vec as opposed to a std::deque then? It guarantees constant time pushes to the back and constant time random element access via operator[][0].
I think the case for std::vector::reserve() is when you know you are about to add N elements via push_back(), you call reserve() with the appropriate size to ensure there is only one reallocation caused by that addition of N elements.
I think the case for std::vector::reserve() is when you know you are about to add N elements via push_back(), you call reserve() with the appropriate size to ensure there is only one reallocation caused by that addition of N elements.
[0] https://www.cplusplus.com/reference/deque/deque/operator[]/