Peter Dimov wrote:
Eric Niebler:
I'm glad we know how to write the identity function object in C++0x. What about in C++03?
I'd put the C++03 overloads in an #else block; apart from that, this identity function object is correct.
OK, thanks. Just for my own understanding, leaving the C++03 overloads in -- as well as the nested result<> template -- doesn't make it wrong, correct? Just not minimal. IIUC, this has implications for people wanting to write TR1-style function objects today. I think Shunsuke may be right in that we need an rvalue_wrapper so that it is possible to write function objects that will continue to work unmodified in C++0x. That is, my use of reference_wrapper to carry lvalue-ness has it backwards. T const & should be assumed to be a const lvalue, because it will mean that unambiguously in C++0x. FWIW, I think fusion::make_vector()'s use of reference_wrapper is also incorrect. :-( -- Eric Niebler Boost Consulting www.boost-consulting.com