[Sorry, e-mail client acting up, ignore my previous email] [Nathan Ridge]
Of course, both use cases are worthwhile and deserve having a class for them in boost, and one's push_back should assert and the other's should throw. We can call one capacity_array and the other stack_vector, or whatever better names we come up with - but let's not give them the same name, when they are very different beasts.
[Nevin Liber]
How could it ever be a "drop-in replacement for vector"
For over a decade, the mental model for calling push_back, insert, resize, etc. is that it they have no preconditions to check. This is true *for every standard container* (which supports the corresponding operation, of course). You want to *silently* break that consistency. That will lead to buffer overrun bugs, which we know are hard to debug and
I don't have any strong feeling about this, but I would be OK with changing the name of capacity_array's push_back() to something else for this reason (in which case it would not have a method named push_back at all). Regards, Nate