[Boost-users] How to create a compilation warning

From: Remi Ricard (remi.ricard_at_[hidden])
Date: 2007-12-20 15:32:15

Hi,

I want to warn user about a possible miss use of a function.

Now I'm only able to stop the compilation with the following code

template <typename ValueType>
class simVec3 {
.........
/// Unary multiply by scalar.
/// @param rsh The scalar to multiply the vector with
template<class T> simVec3<ValueType>& operator *= (const T& rhs)
{
// The function should not be use like this
// simVec<int> vec(1, 1, 1);
// a *= 0.3; // since what a will contain is [0, 0, 0]
BOOST_MPL_ASSERT_NOT(( boost::mpl::and_<     \
        boost::is_floating_point<T>,          \
        boost::is_integral<ValueType> >  ));

       ValueType s=static_cast<ValueType>(rhs);
       vec[0]*=s; vec[1]*=s; vec[2]*=s; return *this;
}

What I would want is something like
#if  A_meta_function_returning_1_if_int_double
#pragma message("simVec::Possible type truncation")
#endif

instead of the BOOST_MPL_ASSERT_NOT

I also tried something like:

template <bool x> struct AA;
template <> struct AA<true> { enum {value = 1 }; };
template <> struct AA<false> { enum {value = 0}; };

template <typename U, typename V>
double
myfct(U u, V v)
{
#if ( AA< boost::mpl::and_< boost::is_integral<U>, \
                             boost::is_floating_point<V> > > ::value )
#pragma message("****** Hellop *********")
#endif

   return u + v;
}

But the compilation is complaining about an unmatched parenthesis

Remi