Re: [boost] [range] [general] making member functions SFINAE-friendly

Subject: Re: [boost] [range] [general] making member functions SFINAE-friendly
From: Thorsten Ottosen (thorsten.ottosen_at_[hidden])
Date: 2013-02-21 05:18:14

On 20-02-2013 22:12, Neil Groves wrote:
> On Wed, Feb 20, 2013 at 9:02 PM, Jeffrey Lee Hellrung, Jr. <
> jeffrey.hellrung_at_[hidden]> wrote:
>
>> On Wed, Feb 20, 2013 at 12:55 PM, Neil Groves <neil_at_[hidden]
>>> wrote:
>> [...]
>>
>>> I agree. My suggestion didn't have a new base class. I think by making
>>> boost::size(rng) call range_size(rng) we can provide an extension method
>>> similar to that already provided for boost::begin(rng) and
>> boost::end(rng).
>>>
>>
>> You mean like range_calculate_size [1] ?
>>
>> Exactly I thought that when I introduced this it has been quite
> successful, and that we could build upon this by adding the optimal
> implementations for standard library components. I have been using this as
> an extension mechanism privately in this manner for a while and it has
> worked well for me. I wanted to get other peoples views on this solution
> before making the extension mechanism more widely used and optimised by
> default for the standard library containers.

I would like to keep boost::size() O(1). Anybody that writes code 
relying on boost::size() should know that this is guaranteed.

As I understand it, there is a wish from som users to get a size even 
when O(1) time is not possible. This suggest to me that we also need to
extend boost::distance() to work for containers.

Either way, customizing a trait/providing an overload for every standard 
and boost container seems to be a solution that scales poorly
and which requires huge amounts of code to be included.

-Thorsten