Re: [boost] Stack-based vector container

Subject: Re: [boost] Stack-based vector container
From: Michael Caisse (boost_at_[hidden])
Date: 2010-12-28 18:17:37

On 12/28/2010 03:03 PM, Gregory Crosswhite wrote:
> Hey everyone,
>
> In the course of my work as a computational scientist I have written a 
> container that emulates std::vector, but which is backed by an array 
> whose size is fixed at compile time.  Concretely, the class looks 
> something like the following:
>
>     template<typename T,unsigned int buffer_size> class static_vector {
>         ...
>         protected:
>             T data[buffer_size];
>             T* end_ptr;
>             size_t current_size;
>     }
>
> where in the [...] there are methods that emulate (at this time, 
> partially) the interface of std::vector, save that the size of the 
> static_vector is not allowed to grow beyond the buffer_size.
>
> The advantage of using a static_vector over vector is performance.  In 
> my code I have performed benchmarks that show up to a 30% performance 
> boost of static_vector over vector;  the benefit occurs most stongly 
> when working with lots of arrays of small objects, so that the use of 
> dynamic memory rather than stack memory appears to add significant 
> overhead to the computation.  (Note that I when running these 
> benchmarks I would use std::vector::reserve() to pre-allocate the 
> array so that std::vector would not perform multiple allocations as 
> the container grew, so that should not have been a source of overhead.)
>
> It seems to me that it would be useful to have this functionality 
> generally available as a library, and in particular it might be a good 
> fit for the boost family of libraries.  Is there any interest out 
> there for having such a library in boost?  If so, I would be happy to 
> do the work of taking what I have and fleshing it out so that it can 
> function as a drop-in replacement for vector, which means modeling the 
> Random Access Container and Back Insertion Sequence concepts as well 
> as adding capacity() and reserve(size_t) (no-op) methods.
>
> Thoughts?
>

How is this different than boost::array?
<http://www.boost.org/doc/libs/1_45_0/doc/html/array.html>

-- 
Michael Caisse
Object Modeling Designs
www.objectmodelingdesigns.com