Re: Reserve_Capacity for Unbounded_String?

[Simon Wright <simon.j.wright@mac.com>]

Robert A Duff <bobduff@shell01.TheWorld.com> writes:

> It's the copy I'm wondering about, not the new and free so much.
> To append N characters to an unb string requires quadratic copying
> (copying a char N**2 / 2 times).
>
> If you double the allocation every time, it's amortized linear.
> Yes, you waste some space that way.

I made a limited Unbounded_String type (with an Append operation) that
works this way when faced with a similar problem (I am stuck on a
rather old GNAT which allocates every time). 30% performance
improvement overall, as I recall.