Re: Query regarding the use/limitiations of traits in metaprogramming

From: whastingsnj (Hastings5_at_[hidden])
Date: 2002-05-07 21:06:36

The following works as desired in CBuilder C++ 6.0:
As you have discovered, Borland has a hard time with compile-time 
constants used in template parameters.

#include <typeinfo>
#include <iostream>
#include "boost/config.hpp"

template <class T>
struct traita { BOOST_STATIC_CONSTANT(int, value=0); };
template <>
struct traita<int> { BOOST_STATIC_CONSTANT(int, value=1); };

template <class T, int>
struct trait1 {};

template <class T>
struct trait
{
        BOOST_STATIC_CONSTANT(int, value=traita<T>::value);
        typedef trait1<T, (traita<T>::value)> t1;
};

int main(int argc, char* argv[])
{
        std::cout
        << typeid(trait<int>::t1).name()
        << std::endl
        << trait<int>::value
        << std::endl
        ;
        return 0;
}