[boost] Re: [pointer container] copyability

From: Aleksey Gurtovoy (agurtovoy_at_[hidden])
Date: 2005-04-28 09:11:27

David Abrahams writes:
> Aleksey Gurtovoy <agurtovoy_at_[hidden]> writes:
>
>> David Abrahams writes:
>>> "Thorsten Ottosen" <nesotto_at_[hidden]> writes:
>>>> the second reason is that value-based and OO programming are different
>>>> and are best kept seperate; there are different idioms, different
>>>> parts of the langauge is being used.  
>>>
>>> That's a very paternalistic approach to library design, and rather
>>> unprecedented.  Normally the only reason to make functionality that
>>> you're implementing anyway hard to access is that it introduces
>>> potential correctness problems, e.g. undefined behavior.  Efficiency
>>> considerations are usually only used when deciding whether or not to
>>> provide functionality at all. for example, that's why we don't have
>>> std::vector::push_front.
>>
>> To be fair, usually the "disabled" functionality is still available
>> through other means, e.g. you can still do
>>
>>     v.insert( v.begin(), ... ) // == v.push_front( ... )
>>
>> and
>>
>>     std::advance( bi, n ) // == bi + n
>
> Yes, but the other part of the convention in those cases is that we
> only do it when there's a big-O difference.  In the case of
> ptr_container clone() is O(N) just like a copy construction would be
> for any other container.

Good point.

-- 
Aleksey Gurtovoy
MetaCommunications Engineering