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

You need your remap trait to simply map from input types to output types, and have your foo(int) interface function delegate to a foo_implementation::type>(int) implementation. i.e.:

template 
struct remap {
    // Default: Output type is the same as input type.
    typedef T type;
};

template <>
struct remap {
    typedef unsigned char type;
};

template <>
struct remap {
    typedef unsigned char type;
};

template 
void foo_impl(int x);

template <>
void foo_impl(int x) {
    std::cout << "foo_impl(" << x << ") called\n";
}

template 
void foo(int x) {
    foo_impl::type>(x);
}

See it live at ideone.com.

That said, it might be realistically simpler to define foo_char, foo_int and foo_short and just call the correct one from client code. foo() isn't syntactically much different from foo_X().