On Tue, 2005-10-04 at 09:23 +0200, Matthias Troyer wrote:
On Oct 4, 2005, at 1:37 AM, Ian McCulloch wrote:
You still have not stated what advantages such a container would have over a resizable container. In other words, if you omit the resize() et. al. from std::vector, what extra functionality can be gained in return?
I see advantages in a variant of this idea, with a compile-time fixed capacity, an implementation of which was done a few years ago by Synge Todo and posted here. There the advantage is that pointer dereferencing can be avoided, and memory usage is minimized.
Another advantage is that you can store iterator to the array in other structures without having a resize in parallel that invalidates all the stored iterators. These are difficult to find bugs... Not that it is impossible to use the current vector by getting the size right at construction time, but the rule "never use resize" is difficult to enforce. Also bound checking might cost less as no operation is susceptible to change the size of the container (and thus an intelligent compiler might remove many checks). And for multidimensionnal arrays, having bounds defined at compile time can help optimization of array access (by generating optimal computation of the array index).