Re: [boost] Road to low-quality-code is paved with good intentions of dropping dependencies

7 Jan 2015

      El 07/01/2015 a las 17:48, Nevin Liber wrote:
...
On 7 January 2015 at 09:22, Beman Dawes  wrote:
...
For all the type traits that are now supported by the standard library
in use, it might be nice if #include
 brought in the standard library
version. So eventually the many boost libraries that use only type
traits that have been standardized would have no dependencies on the
actual boost implementations.
In order to do that, we need to somehow unify the following unrelated types:
std::integral_constant
boost::integral_constant
boost::mpl::integral_c
We could try to improve interoperability with a type that accepts 
anything that seems a true/false-type. Something like:

namespace boost {
namespace core_traits {

template<bool Value>
struct bool_type
{
    template<class BoolType>
    bool_type
     (BoolType
     , enable_if_internal_bool_value_is_equal_to
          <Value>::type * = 0
     );
};

}  //namespace core_traits {
}  //namespace boost {

So every custom integral_constant would be convertible to bool_type, and 
a very basic trait that does not derive from integral_constant:

template<class T>
struct is_mytrait
{
    static const bool value = /**/;
};

could be used with tag dispatching or enable_if + is_convertible.

Best,

Ion

Re: [boost] Road to low-quality-code is paved with good intentions of dropping dependencies

Ion Gaztañaga