Question

I am trying to compile solutions and projects on MSVC++ 10 that worked fine in MSVC++ 9, and I am having trouble with it, mostly getting the following message:

error C2888: ‘std::hash’ : symbol cannot be defined within namespace ‘tr1’

on the following code:

namespace std {
namespace tr1 {

template <>
struct hash< Rubedo::eChannelFamily >
{
    std::size_t operator()( const Rubedo::eChannelFamily& Key ) const
    {
        return ( int ) Key;
    }
};
}}

I would be perfectly happy if I could do one of the following:

• Modify the code to fix the bugs and compile cleanly;
• Force the compiler to behave like MSVC++ 9.0.

How would I do something like that?
Thank you very much in advance.

Answer 1

hash is in namespace std in VS2010, as it’s part of C++0x’s Standard library, not std::tr1. Just remove the tr1 section and the compiler should be fine.

template<> class std::hash< Rubedo::eChannelFamily >>
    : public std::unary_function<const Rubedo::eChannelFamily, size_t>
{
public:
    size_t operator()(const Rubedo::eChannelFamily& ref) const {
        return ( int ) ref;
    }
};

This is a fairly trivial modification of a hash I have for my own type which compiles successfully.