Cory Nelson wrote:
Say you have a large structure that you only need to build once, and won't modify after that except to delete it. Ideally:
- One arena (what you described) could service all the objects in the entire structure. This gives you high locality and no bookkeeping overhead.
- The objects wouldn't hold an allocator (reference to the arena). They only need to be built once, so keeping a reference around for future allocations is needless overhead.
- The arena would not be in global/static storage.
- The objects would all still have their destructors called.
This is impossible with std:: containers. I've been using C strings, wrappers around intrusive (to call destructors), and a tr1::array-ish class that lets me set pointer & size.
A lot of the time the overhead of std:: containers is acceptable for the convenience they give, but in my situation (Windows Mobile, need to be very tight on usage) it isn't.
I think the problem is fairly common and even desktop apps would benefit from such a design IF it where made convenient. I admit, I can't think of a convenient way to do this (though intrusive comes quite close).
It does not sound easy to solve, specially if you don't want the arena to be global/static. Interesting, though. Regards, Ion