March 2008 - Boost - lists.boost.org

Visitation using RTTI
by Mathias Gaunard 29 Mar '08

29 Mar '08

Boost.variant provides visitation over an object whose types is within a certain set. To identify the type of the object, it uses an additional int that uniquely identifies the type of the object within the set. However, RTTI already provides unique identification for objects of polymorphic types within all types. I'm well aware that typeid(SomeType) is not a constant expression (which is quite a shame really, especially since I can't see any technical reason why it couldn't be) but it is still possible to do something like this: switch(typeid(o).name()[0]) { case 'F': switch(typeid(o).name()[1]) { case 'o': switch(typeid(o).name()[2]) { case 'o': switch(typeid(o).name()[3]) { case 0: // object of type "Foo" break; default: // unknown type } default: // unknown type } default: // unknown type } default: // unknown type } By providing the name of the types as a compile-time string, it could be possible to generate the implementation-specific mangled name and, from it, this kind of switch statement. This would allow O(1) (but with a possibly large constant) visitation of objects of polymorphic types non-intrusively. An utility could provide something like this: struct Base { virtual ~Base() = 0; }; struct Derived1 : Base { virtual Derived1() {} }; struct Derived2 : Base { virtual Derived2() {} }; struct Derived3 : Base { virtual Derived3() {} }; typedef mpl::map< mpl::pair< mpl::string<'D', 'e', 'r', 'i', 'v', 'e', 'd', '1'>, Derived1 >, mpl::pair< mpl::string<'D', 'e', 'r', 'i', 'v', 'e', 'd', '2'>, Derived2 >, mpl::pair< mpl::string<'D', 'e', 'r', 'i', 'v', 'e', 'd', '3'> Derived3 > > derived_types; struct Visitor { typedef void result_type; template<typename T> void operator()(T&) const { // something useful } }; // b can actually be of any type derived from Base void foo(const Base& b) const { poly_visit<derived_types>(b, Visitor()); } Is there some interest in such a tool?

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[config] BOOST_HAS_NRVO not defined for VC++ 8.0 and later?
by Beman Dawes 29 Mar '08

29 Mar '08

Looking at config_info results, BOOST_HAS_NRVO doesn't appear to be defined for VC++ 8.0 and later. But see http://msdn2.microsoft.com/en-us/library/ms364057(VS.80).aspx. According to that, 8.0 and later does support the named return value optimization. What am I missing:-? --Beman

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[Proto] Reminder: review will end March 28th
by Hartmut Kaiser 28 Mar '08

28 Mar '08

Hi all, this is just a gentle reminder for all intending to write a Proto review to finish it really soon. At the same time this should be understood as an encouragement for all of you still hesitating to write one because you perhaps think the library is too complicated or too exotic and you probably won't be able to write an adequate review. Please do not hesitate! Even a short review based on your experience or based on what you've read in the documentations is highly appreciated. Please consider writing your review not later than March 28th. If you won't be able to finish it in time but still intend to write a review, please contact me directly so we can work out the details. Regards Hartmut Review manager

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Preview 2 of a template Geometry Library
by Barend Gehrels 28 Mar '08

28 Mar '08

Dear list, Herewith the URL to the second preview of Geodan's Geometry Library, including documentation and examples. The first preview was sent to this list in January. There were several valuable comments and they are processed. The documentation contains a page with the most important changes. The very most important change is done in the type geometry::point. The new design is now described here: http://geometrylibrary.geodan.nl/points.html As in the first preview, there are still implementation issues and algorithmic details to be figured out or to be implemented. This is a preview and not yet a real submission. However I think that the community will get a feeling how it works and/or should work. The URL with complete documentation (now generated using Doxygen) is here: http://geometrylibrary.geodan.nl/index.html, sources and headerfiles can be downloaded from "Related pages". Best regards, Barend Gehrels ------------------------------------- Barend Gehrels, Geodan Holding b.v., Amsterdam, The Netherlands, www.geodan.nl

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[iterator] operator_arrow_proxy constructor should be templated
by Felipe Magno de Almeida 28 Mar '08

28 Mar '08

Hello, operator_arrow_proxy exists to allow a T* to be created for input_iterators, but its constructor is not templated, so it is not possible to create a T from whatever is received. Making operator_arrow_proxy templated solves the problem. Regards, -- Felipe Magno de Almeida

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[spirit] [RC_1_35_0] multiple defined symbols error in static.hpp
by Felipe Magno de Almeida 28 Mar '08

28 Mar '08

Hi, There are linking errors on msvc 7.1 (and probably other compilers) with static.hpp. The structs destructor e default_ctor are defined inside static_ constructors. If I move them to outside the function, they link ok. Regards, -- Felipe Magno de Almeida

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Re: [boost] [1.35.0] Release Candidate 3 available
by David Abrahams 28 Mar '08

28 Mar '08

on Fri Mar 28 2008, Sohail Somani <sohail-Jk4wshXjlOsFFmt/ZbAu/w-AT-public.gmane.org> wrote: > Serialization issues: > > http://svn.boost.org/trac/boost/ticket/1711 > http://svn.boost.org/trac/boost/ticket/1725 > > At least the tests should be updated to show proper workarounds if a new > feature doesn't work properly across popular compilers (1711). I am not > using the bleeding edge (g++ 4.1 - bleeding is 4.3?). That second problem is surely not a compiler dependency but a failure to write a working Jamfile, is it not? -- Dave Abrahams Boost Consulting http://boost-consulting.com

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Re: [boost] [1.35.0] Release Candidate 3 available
by David Abrahams 28 Mar '08

28 Mar '08

on Fri Mar 28 2008, Sohail Somani <sohail-Jk4wshXjlOsFFmt/ZbAu/w-AT-public.gmane.org> wrote: > http://svn.boost.org/trac/boost/ticket/1711 > http://svn.boost.org/trac/boost/ticket/1725 > > At least the tests should be updated to show proper workarounds if a new > feature doesn't work properly across popular compilers (1711). I am not > using the bleeding edge (g++ 4.1 - bleeding is 4.3?). > > I leave it up to you to decide the showstopping-ness of it all but the > tests will fail (and so will code that tries to mimic the tests) on a lot > of machines. Robert pinged Dave about the issue but I haven't heard > anything more. He did? I didn't get any private email about it and haven't been able to keep up with this list for the last few weeks. -- Dave Abrahams Boost Consulting http://boost-consulting.com

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[function] breaking change detection
by shunsuke 28 Mar '08

28 Mar '08

Hi, boost::function<> template arity seems to be changed. Is there anyway to detect the change? e.g. BOOST_FUNCTION_HAS_NO_ALLOCATOR_PARAMETER My library is going to be reviewed 2 days later, but is partly broken by that change :-( Regards, -- Shunsuke Sogame

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Boost support requests
by Marshall Clow 28 Mar '08

28 Mar '08

Thanks to everyone who looked at the support requests These are the ones that are left. I'm hoping that we can deal with all of these by the time 1.35.0 is released.... [ Anyone want to look at #426 and #597 ] Thanks in advance! 2 az_sw_dude 1 nobody 1 no-maintainer 1 jsiek 1 johnmaddock 1 djowel 1 dave 1 anthonyw 1 agurtovoy agurtovoy 816 duplicat initial members -> erase_key postcond. fail anthonyw 1053 Error using boost::mutex and C++/CLI az_sw_dude 605 support new 2007 DST rules for timezone db az_sw_dude 614 new timezone db file for #1471723 - 2007 DST support dave 1262 [Boost.Iterators] Reasoning for boost::pointee<> not supporting back_insert_iterator? djowel 1221 Section names may cause html names to be too long johnmaddock 1636 Bug in regex? jsiek 580 Max Flow Algorithm no-maintainer 426 lambda vs pure virtual functions nobody 597 Non-basic-source-character-set characters conflict with MSVC -- -- Marshall Marshall Clow Idio Software <mailto:marshall@idio.com> It is by caffeine alone I set my mind in motion. It is by the beans of Java that thoughts acquire speed, the hands acquire shaking, the shaking becomes a warning. It is by caffeine alone I set my mind in motion.

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