Template specialization for multiple types

Question

Title is a little ambiguous.

Lets say I have a template defined as:

template < typename T >
void foo ( int x ) ;
template <>
void foo

        

Answer 1

One possibility is to specialize a class template for multiple types at once:

// from: http://en.cppreference.com/w/cpp/types/enable_if
    template
    struct enable_if {};

    template
    struct enable_if { typedef T type; };

template < typename A, typename B >
struct is_same
{
    static const bool value = false;
};
template < typename A >
struct is_same
{
    static const bool value = true;
};


template < typename T, typename dummy = T >
struct remap;

template < typename T >
struct remap
<
    T,
    typename enable_if<    is_same::value
                        || is_same::value, T >::type
>
{
    void foo(int);
};


int main()
{
    remap s;
    s.foo(42);
}

---

Another possibility is to specialize a class template for categories of types (type traits):

#include 

template < typename T >
struct is_integer
{
    static const bool value = false;
};
template<> struct is_integer { static const bool value = true; };
template<> struct is_integer { static const bool value = true; };


template < typename T, typename dummy = T, std::size_t S = sizeof(T) >
struct remap;

template < typename T >
struct remap
<
    T
    , typename enable_if::value, T>::type
    , 1 // assuming your byte has 8 bits
>
{
    void foo(int);
};


int main()
{
    remap s;
    s.foo(42);
}