Re: [boost] Re: Re: Re: Re: Re: [Formal review] Collection Traitslibrary

From: Peter Dimov (pdimov_at_[hidden])
Date: 2004-05-07 09:45:41

Thorsten Ottosen wrote:
> "Peter Dimov" <pdimov_at_[hidden]> wrote in message
> news:00f601c43438$67a5ab60$1d00a8c0_at_pdimov2...
>> Thorsten Ottosen wrote:
>>> "Peter Dimov" <pdimov_at_[hidden]> wrote in message
>>> news:003b01c4337c$83b49df0$1d00a8c0_at_pdimov2...
>>>> Thorsten Ottosen wrote:
>>> [snip]
>
>>>> Range is begin(), end();
>>>
>>> So you want size() and empty() to be removed from the Range Traits?
>>
>> I just omitted them for brevity, but since you ask, size() is
>> essential since it can be O(1) when distance( begin(), end() ) is
>> O(N), but it seems to me that empty() is always begin() == end(), so
>> it can be removed. (begin() and end() should be O(1).)
>
> hm...empty() is O(N) for strings if implemented as end() - begin(),
> but O(1) currently.

Yes, you are right, I missed that.

This however reminds me about a related issue. If I read the implementation
correctly, the size of T[N] is usually N, but it's N-1 when T is char or
wchar_t. I understand that this is being done to support "character
literals", but it obviously has the potential to introduce subtle off by one
bugs, especially in generic code.