How to partially specialize a class template for all derived types?

Question

I want to partially specialize an existing template that I cannot change (std::tr1::hash) for a base class and all derived classes. The reason is that I\'m usin

Answer 1

Instead of modifying std::tr1::hash you should make your own namespace and define there new structure hash which inherited from std::tr1::hash or is specialized for CRTPBase.

template 
struct CRTPBase
{
    size_t hash() {return 0; }
};

struct AA : CRTPBase  {};
struct BB {};
//
namespace mynamespace {

template  
struct hash : std::tr1::hash {};
//
template 
struct hash, Derived>, char>::type >
{    
    size_t operator()(const CRTPBase & base) const     
    {         
        return base.hash();     
    }
};

} // namespace mynamespace {}
//
//
void ff()
{
    using namespace mynamespace;

    hash aa;  // my hash
    hash bb;  // std::tr1::hash

}