Re: [boost] devector feedback request

Subject: Re: [boost] devector feedback request
From: Thorsten Ottosen (tottosen_at_[hidden])
Date: 2015-07-27 09:46:10

Hi Matthias,
>  From the documentation, it sounds like a devector is strictly superior
> to std::vector, as it offers a superset of functionality. It would be
> great if you could discuss a bit more the trade-offs, for example, in
> which cases a devector is inferior to a std::vector performance-wise.

This comparison makes most sense if the two containers are configured in 
a compatible way. That is, no internal buffer for devector and the same 
eponential growth of the buffer.

In this senario one should expect std::vector to be superior by a very 
small constant factor for many operations (so there is /never/ any 
big-Oh advantage of std::vector). For example, to initialize a default 
std::vector, you need to initialize three data members, whereas the 
devector needs to initialize four data members. Similarly, devector 
sometimes needs to adjust two members instead of one.

For many operations, I expect there will be very little difference, and 
as soon as you start using stuff that a devector can do efficiently, 
then devector code will perform much better.

kind regards

Thorsten