[Boost-users] [boost-users] enable_if and checking if class derives from boost::operators does not work.

From: chun ping wang (cablepuff_at_[hidden])
Date: 2007-10-12 19:33:52

namespace boost
{
       template <class T, class U>
        char (& is_op_test(boost::operators<T,U> const&) )[2];

        template <class T>
        char is_op_test(T const&);

        template<class T>
        T const& make();

        template <class T>
        struct is_operators
         : boost::mpl::bool_<(sizeof(is_op_test(make<T>())) == 2)>
        {};
}
and this function declaration.
template <typename T,
     template <typename ELEM, typename = std::allocator<ELEM> >
     class CONT
>
typename boost::enable_if<boost::mpl::or_<boost::is_integral<T>, boost::
is_operators<T> >, CONT<T> >::type
primelist(const T& MAX_BOUND, const T& K, boost::function<bool(const T&,
const T&)> f);

BigInteger class declaration looks like this..

class BigInteger : public BigUnsigned, boost::operators<BigInteger>,
boost::operators<BigInteger, int>
{
};

I compile with T = int and it works.

When i compile with T = BigInteger I get the following errors.

on visual c++.
error C2770: invalid explicit template argument(s) for
'boost::enable_if<boost::mpl::or_<boost::is_integral<T>,boost::is_operators<T>
>,CONT<T>>::type primelist(const T &,const T &,boost::function<bool(const T
&,const T &)>)'
        ./cs512/c++/primeMain.cpp(24) : see declaration of 'primelist'"

on mingw dev-cpp i get this error.
unable to find function....

In both cases passing BigInteger does not work.

thanks for the help.

BigInteger does derive from boost::operators and theirs two overload.