Re: [boost] [range] range_size metafunction deprecated?

From: Thorsten Ottosen (thorsten.ottosen_at_[hidden])
Date: 2007-03-01 05:49:39

shunsuke wrote:
> Thorsten Ottosen wrote:
> 
>>shunsuke wrote:
>>
>>>Hi,
>>>
>>>I noticed Range Library Core proposal
>>>(http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2068.html)
>>>removed 'range_size' metafunction.
>>>It was replaced by 'range_difference'?
>>>(But, cvs head is not affected.)
>>
>>Right. A proposal for the standard and boost is two different things.
> 
> 
> The 'boost::range_size' of 'iterator_range' is defined as 'std::size_t'.
> Can it guarantee to represent any difference_type of iterator?

Probably not.

Anyway, I plan to change boost::size() to return iterator_difference.

(If there is one thing I hate about C++ containers it has to be the use
of unsigned.)

>>>If so, why 'std::size' too is proposed?
>>>'std::distance' seems enough.
>>
>>So that you may have the guarantee that the function is O(1) complexity.
> 
> 
> 'std::distance'(24.3.4/1) also seems to guarantee it?

Only for random access iterators. std::size() would only accept random 
access iterators.

-Thorsten