"Beman Dawes" <bdawes@acm.org> writes:
"Gennadiy Rozental" <gennadiy.rozental@thomson.com> wrote in message news:d4ooik$f0h$1@sea.gmane.org...
you're analogy with vector<string> don't quite fit IMO. assigning vector<string> might be quite efficient with very few heap-allocations taking place; assigning ptr_vector<Foo> would cost the same as copy-construction + deallocation.
IMO no performance point could justify omitting assignment operator. If I need vector<ptr_vector<Foo> > - it's my decision and I will deal with performance penalties.
I agree very much with Gennadiy and others who argue that performance concerns should not cause an otherwise useful operation to be omitted.
In this case, the operation is not omitted at all, it's just spelled in a way that's incompatible with most of the rest of C++, in order to make certain things very inconvenient (i.e. "force you to think about the cost of copying"). That's what makes it so frustrating. Contrary to Peter, I have no serious problem with the idea that some achievable but poorly performing operations (e.g. operator + on a bidirectional iterator) might be omitted. I have a big problem with the idea that a function as basic as copy construction should be made available, but only with a nonstandard spelling. -- Dave Abrahams Boost Consulting www.boost-consulting.com