A couple things related to this. There's a thread about it in the General Discussions area. Basically it will be easier to move objects rather than copy them. So something heavyweight like a vector can be stored in another container with fewer efficiency issues. Instead of the heavyweight object getting copied everywhere, it gets moved. I was just kidding about waiting until then, though.
Another note about your previous question- If the parser really has a short lifetime like in your example, then you might be able to pass the vector into the parse function by reference. In that case you won't need to do any copies because you can get the vector directly from the map:
Code:
parser p;
p.parse(my_cache.map_[key_string]);
