On Thu, Feb 21, 2013 at 2:18 AM, Thorsten Ottosen < thorsten.ottosen@dezide.com> wrote:
On 20-02-2013 22:12, Neil Groves wrote:
On Wed, Feb 20, 2013 at 9:02 PM, Jeffrey Lee Hellrung, Jr. < jeffrey.hellrung@gmail.com> wrote:
On Wed, Feb 20, 2013 at 12:55 PM, Neil Groves <neil@grovescomputing.com
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.
Agreed. 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.
+1 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.
This can be mitigated somewhat if range_calculate_size(r) defaults to r.size() if that is available, but there's the tradeoff that r publishes a non-O(1) size member function, in which case range_calculate_size must be explicitly overridden. And then there are the cases when r.size() static asserts :/ In any case, providing an overload for every standard and boost container is what we already do with swap, so there is precedent. - Jeff