Const static members in a template class?

[ElCattivo]

Hi there,
I have a little problem with template classes and their specialization. Here is a short example:

template <typename T>
struct A{
// some typedefs

const static T my_constant;
};

template<>
struct A<double>{
//some typedefs

const static double my_constant = 4.23;
};

The above example is not compiling, because of the assignment of the const static double. Double needs a constructor, but that doesn't work (or seems not to work) with static.

I'm not sure, if it works at all in C++ that way. All I want is a template struct with some typedefs and a constant which is different for different specializations. Don't think it has to be static, but that would be better style, wouldn't it?

Thanks for helping.
ElCattivo

[vlad from moscow]

If your compiler supports the new feature constexpr of the C++ 2011 Standard then try to change

const static double my_constant = 4.23;

to

constexpr static double my_constant = 4.23;

[JLBorges]

template < typename T > struct S { static T sval ; } ;

template < typename T > T S<T>::sval = T() ;


template <> struct S<double> { static double sval ; } ;

double S<double>::sval = 45.678 ;

[ElCattivo]

ok, I will try these two things. Thanks :)