On Sat, Jul 16, 2011 at 11:02 PM, Joel falcou <joel.falcou@gmail.com> wrote:
On 17/07/11 04:58, Jeffrey Lee Hellrung, Jr. wrote:
* I *think* all generated metafunctions should also expose a nested "type" typedef in addition to a nested "value" static bool in order to be fully Boost.MPL compatible, but...I'm not sure on this one. For some reason, I've always followed this practice, I think because it allows has_type_xxx<T> to be used as a nullary Boost.MPL metafunction. Can someone comment on this?
Yes, could be nice to have as it will make the metafunction proper nullary MPL one. I suggest findign a way to inherit from boost::mpl::bool_ whenever possible.
I think inheritance might be inconvenient in this case, as I'm guessing (I haven't yet looked at the implementation) the value member is computed as value = sizeof( ... ) == sizeof( ... ); Probably sufficient to BOOST_STATIC_CONSTANT( bool, value = ... ); typedef this_metafunction_name type; // 1 typedef boost::integral_constant< bool, value > type; // 2 typedef boost::mpl::bool_< value > type; // 3 where I think any of 1, 2, or 3 is fine. - Jeff