Niall Douglas wrote:
However I am thinking here in terms of WG21 standardisation, specifically SG14's work on a std::vector upgrade which doesn't have the really unfortunate unpredictable latency. The general idea is that a low latency std::vector would never expand its capacity automatically, instead it would return success + capacity approaching warning status. You then could schedule the construction of a new, bigger vector outside the hot path.
I find this example as unconvincing as Lawrence's original one. For one, vector functions that grow the size typically return void. So you could just turn that into bool or an enum and you'd be done. For another, when you're in the hot path, the "capacity warning" status is not actionable, so it's of little use. Instead, when you get out of the hot path (or, better yet, before you get into it), you'd simply check capacity(), see if it's yellow/red, and reserve. Or not even check, just reserve( size() + <hot path max size requirement> ).
so the idea was that expected
could be returned.
Sounds like the discussion took place in a pub. Not that there's anything wrong with that. :-)