How can I specialize a C++ template for a range of integer values?

Question

Is there a way to have a template specialization based on a range of values instead of just one? I know the following code is not valid C++ code but it shows what I would li

Answer 1

Try std::conditional:

#include 

template
class circular_buffer {

    typedef typename
        std::conditional< SIZE < 256,
                          unsigned char,
                          unsigned int
                        >::type
        index_type;

    unsigned char buffer[SIZE];
    index_type head;
    index_type tail;
};

If your compiler doesn't yet support this part of C++11, there's equivalent in boost libraries.

Then again, it's easy to roll your own (credit goes to KerrekSB):

template 
struct conditional {
    typedef T type;
};

template   // partial specialization on first argument
struct conditional {
    typedef F type;
};