"Andy Little" <andy@servocomm.freeserve.co.uk> writes:
"David Abrahams" <dave@boost-consulting.com> wrote
"Andy Little" <andy@servocomm.freeserve.co.uk> writes:
Also I suspect that the change from boost::is_same to std::is_same is going to break a lot of code, unless the mpl tag requiremnet is lifted ;-)
Ditto.
The boost type_traits integral constant is derived from mpl::integral_c which has a tag type member, without which boost:::integral_constant wouldnt work with mpl types such as equal_to.
?? equal_to isn't a type.
The std version doesnt specify the tag, nor does the boost type_traits version in its documentation. Without the tag, boost::integral_constant would not work with mpl types such as equal_to as demonstrated in another mail in this thread. Therefore changing from boost::integral_constant to std::integral_constant will break code that uses mpl. Maybe its not important, but the innocent std:: integral_constant will appear to be bug ridden.
I see no requirement that a `tag' type member be included in http://boost.org/libs/mpl/doc/refmanual/integral-constant.html. However, it does look like the current implementation of equal_to depends on the presence of `tag'. I'm not sure what the plan was here; Aleksey? It would be easy enough to make most of the MPL numeric metafunctions work on types that don't supply `tag'. -- Dave Abrahams Boost Consulting www.boost-consulting.com