The following code is valid: #if 1 #include <boost/ref.hpp> int const & (&b_unwrap_ref) (int const &) ((::boost ::unwrap_ref)); #endif The following code, however, is not (as of libstdc++ 4.5.1): #if 1 #include <tr1/functional> int const & (&tr1_unwrap_ref) (int const &) ((::std ::tr1 ::unwrap_ref)); #endif With the following diagnostic:
error: ‘unwrap_ref’ is not a member of ‘std::tr1’
So I started to ask myself: WTF? * It turns out that unwrap_ref did not make it to TR1, although reference_wrapper did. But why? * Because ref.hpp did not provide it when TR1 was formed? [1] Implication: * unwrap_ref (std:: reference wrapper) is a mismatch. #if 1 void test () { unwrap_ref (::boost ::cref (0)); unwrap_ref (::std ::tr1 ::cref (0)); // error: ‘unwrap_ref’ was not declared in this scope ::boost ::unwrap_ref (::std ::tr1 ::cref (0)); // error: error: invalid initialization of non-const reference } #endif Shouldn't we do something about it? Like, e.g., extend the scope of unwrap_ref to cover the corresponding standard class? This would at least allow expression #3. Chris ___ [1] <URL: https://svn.boost.org/svn/boost/!svn/bc/16384/trunk/boost/boost/ref.hpp >