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

Subject: Re: [boost] Interest in StaticVector - fixed capacity vector
From: Peter Dimov (pdimov_at_[hidden])
Date: 2011-10-15 10:40:47

Dave Abrahams wrote:
> Nobody likes "unefined behaviour???"  But please allow me to replace
> that comment with:
>
>      "// throws an exception???"
>
> It's just not the most appropriate response.  For those who want
> checking, dropping into the debugger or dumping core or logging and
> terminating would be better, and those who don't will be annoyed to pay
> for unneeded checks when their code is correct.

We (as in the authors of the example) fall in neither category of yours. We 
want the algorithm that does push_back to terminate when it reaches 
capacity. Which is exactly what it will do, without having to be rewritten.

> Why should the library be locked into providing what is almost always a 
> suboptimal response?

It's your (and others') assertion that this is almost always a suboptimal 
response. You haven't backed it up. Yes, it's trivial to argue that logic 
errors should not be exceptions, but why is push_back over capacity "almost 
always" a logic error? Heck... why is it a logic error at all, except in the 
trivial case in which you start with an empty static_vector<T, N> and do 
exactly N push_backs, a case which more or less calls for an array because 
it doesn't exploit the fact that size() can be different from capacity()? 
Stated differently, is the number of push_backs always a compile time 
constant? Does it not come, more often than not, from runtime input?