Re: [boost] [range] Proposal: addition of front(), back(), at(), operator[]

Subject: Re: [boost] [range] Proposal: addition of front(), back(), at(), operator[]
From: Marshall Clow (mclow.lists_at_[hidden])
Date: 2014-03-24 13:36:26

On Mar 24, 2014, at 2:14 AM, Valentin Ziegler <vziegler_at_[hidden]> wrote:

> Hi Adam,
> 
>> 1. front()
>> returning the reference to the first element precondition (assert): !empty(rng)
> 
>> return *begin(rng);
> 
>> 2. back()
>> returning the reference to the last element precondition (assert): !empty(rng)
> 
>> For BidirectionalRange
>> return *(--end(rng));
> 
> In 99% of all cases above implementations will work just fine. However, there may be rare cases where the lifetime of the reference is bound to the lifetime of the iterator:
> 
> [iterator.requirements.general] 9. Destruction of an iterator may invalidate pointers and references previously obtained from that iterator.

Interesting. I think that in C++14, the committee put that possibility to bed.
See LWG issue 2360 http://cplusplus.github.io/LWG/lwg-defects.html#2360

I’ll open an issue that gets that cleared up.

— Marshall

> 
> Valentin
> 
> 
> --
> Valentin Ziegler | vziegler_at_[hidden]
> Senior Software Engineer
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