On 16/05/2010 1:26, vicente.botet wrote:
* The use of the is_movable metafunction is not clear in the documentation. The name let think to a concept check, that is, is T a model of the Movable concept? But the check is related to whether T is convertible to rv<T>&, and it seems you uses it in Boost.Container to avoid conflicts using enable_if/disable_if. Could you clarify this? Should is_movable be renamed to a more specific name?
Is not clear and after discussing it in previous mails, I think it should be present only for C++03 with another name. It detects whether a class implements move emulation functions. It's useful to sfinae out some overloads in generic functions (eg. push_back in vector, since vector<int> should not instantiate at all any rv<int> type).
* Should the use of BOOST_RV_REF in template classes be protected with is_movable?
* What returns is_movable if BOOST_ENABLE_MOVE_EMULATION is not defined for compilers with rvalue references?
I don't have anything in addition to Jeffrey's explantions for those. Thanks Jeffrey!
* Could you add the requirements of a Movable type? Could we have a trait for this?
Yes, please see my previous post replying Jeffrey.
* I don't know if the next metafunction is correct in C++0x, If correct, could it be used to replace the macro BOOST_RV_REF?
See Jeffrey's explanation. Adding more metafunctions would be correct if we find they might be useful for generic programming. But I don't know if rv<T> & is the correct answer for generic programming using C++0x (add_rvalue_reference, remove_rvalue_reference, is_rvalue_reference). We still don't have enough experience with both rv references and this emulation to know the answer.
* BTW, why BOOST_RV_REF_2_TEMPL_ARGS and BOOST_RV_REF_3_TEMPL_ARGS are needed?
Preprocessor limitations, extra parens won't fix ;-) Regarding the use of Boost.Preprocessor, I aim was to write Boost.Move with very few dependencies. Although support for Boost.MPL was requested in previous discussions, I would like to get this without header dependencies, but I guess Boost.TypeTraits will also depend on MPL, although that could be fixed because traits might go to TypeTraits.
* has_nothrow_move. What are the expected some performance improvements. of movable classes that specialize this to true? Could an example be added?
See http://permalink.gmane.org/gmane.comp.lib.boost.devel/204112
* As the standard uses these more specific ones template<class T> struct has_nothrow_move_constructor;
template<class T> struct has_nothrow_move_assign;
Shouldn't Boost.Move use these
Yes, at least if they are stable in the draft. And maybe they should en end in Boost.TypeTraits, along with has_trivial_destructor after move, which can be used to avoid calling destructors in containers when an element is moved and its destructor does not need to release any resource.
Implementation * I would like to know the reason to don't use is_convertible from Boost.TypeTraits and define your own. * The same for identity?
Dependency issues, but I have no problem to change this. Best, Ion