Re: [boost] Interest in StaticVector - fixed capacity vector

Subject: Re: [boost] Interest in StaticVector - fixed capacity vector
From: Dave Abrahams (dave_at_[hidden])
Date: 2011-10-15 14:47:47

on Sat Oct 15 2011, "Peter Dimov" <pdimov-AT-pdimov.com> wrote:

> Dave Abrahams wrote:
>> on Sat Oct 15 2011, "Peter Dimov" <pdimov-AT-pdimov.com> wrote:
>> > What are the "proper" uses for it?
>>
>> It sounds like you're asking me to prove something for which we both
>> know there's no proof.
>
> Not really. As I already said in the other message, doing more
> push_backs than a compile-time constant size is a logic error only
> when the number of push_backs is a compile-time constant as well. So,
> it follows that it is only proper to use static_vector when the number
> of push_backs is known at compile time. 

Or when you have a fallback response (like dynamic allocation).  But the
right place to put that fallback response is where capacity is exceeded,
not somewhere outside after an exception is thrown.

> So I was wondering what some of these (nontrivial and variable size)
> uses are.
>
> As an example, a case in which 99.4% of the time the number of
> push_backs doesn't exceed capacity is a legitimate use, but it's not a
> logic error, and quite fits the mantra that "exceptions should be
> exceptional". 

I never liked that mantra anyhow, but you're right that it is a
legitimate use *if* your program can handle a particular step failing
.6% of the time.

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com