Support std::hash

[krojew]

boost::uuids::uuid now supports only boost:hash via hash_value(), making it an unnecessary dependency on platforms supporting >= c++11. There also should be a std::hash specialization.

[jeking3]

Hi, thanks for reporting the issue. Can you add any more details or examples?

[krojew]

A typical usage example would be using uuid as the key for std::unordered_map. Since uuid already supports boost::hash, it would be nice to also support std::hash, to make that example work without changing the default hasher. In other words, what's missing is a std::hash specialization for uuid.

[jeking3]

If you can provide a simple code example of this that I could build into a unit test for C++11 or later, I would appreciate it.

[krojew]

A simple example can be:

#include <unordered_set>
#include <boost/uuid.hpp>

// make this compile
std::unordered_set<boost::uuids::uuid> set;

A fast solution can be the use of existing boost::hash_value:

namespace std
{
    template<>
    struct hash<boost::uuids::uuid>
    {
        std::size_t operator ()(const boost::uuids::uuid &value) const noexcept
        {
            return boost::hash_value(value);
        }
     };
}