new Type[count] takes too much?

[Jonathan M Davis]

On Thursday, October 31, 2013 10:15:51 Namespace wrote:
> I'm sure we had already this conversation but I don't find the
> thread.
> 
> T[] buffer = new T[N]; assumes more space than stated (in average
> 2010 elements more. See: http://dpaste.dzfl.pl/af92ad22c). It
> behaves exactly like reserve and that is IMO wrong. If I reserve
> memory with buffer.reserve(N), I want to have at least N
> elements. That behaviour is correct. But if I use new T[N] I
> mostly want exactly N elements and no extra space.
> 
> Thoughts?

You're making the assumption that it would be normal to not want to then 
append to something you allocated with new T[N], and I don't think that that's 
a valid assumption. Also, from what I understand of how allocators work, they 
normally grab memory in sizes which are a multiple of 2, so I would expect it 
to be highly abnormal to ever get exactly the amount of memory that you 
requested. You're pretty much always going to get extra.

- Jonathan M Davis