July 2012 - Boost-users - lists.preview.boost.org

[boost] [type_erasure] Review started (July 18-27, 2012)
by Lorenzo Caminiti 04 Aug '12

04 Aug '12

Hello all, *** The review of Steven Watanabe's proposed Boost.TypeErasure library begins on July 18, 2012 and ends on July 27, 2012. *** THE LIBRARY C++ provides runtime polymorphism through virtual functions. They are a very useful feature, but they do have some limitations. * They are intrusive. In generic programming, we can design an interface which allows third-party types to be adapted to it. * They require dynamic memory management. Of course, most of the problems can be avoided by using an appropriate smart pointer type. Even so, it still acts like a pointer rather than a value. * Virtual functions' ability to apply multiple independent concepts to a single object is limited. The Boost.TypeErasure library solves these problems allowing us to mirror static generic programming at runtime. Library source: http://svn.boost.org/svn/boost/sandbox/type_erasure/ Pre-built documentation: http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure/ You can also download archives with pre-built documentation from: http://sourceforge.net/projects/steven-watanabe.u/files/ YOUR REVIEW Please submit a review to the mailing-list by replying to this email ("[boost] [type_erasure] Review ..." should be in the subject). Please state clearly whether you think this library should be accepted as a Boost library. Other questions you may want to consider: 1. What is your evaluation of the design? 2. What is your evaluation of the implementation? 3. What is your evaluation of the documentation? 4. What is your evaluation of the potential usefulness of the library? 5. Did you try to use the library? With what compiler? Did you have any problems? 6. How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? 7. Are you knowledgeable about the problem domain? Thanks in advance to all who participate in the review discussion -- I'm looking forward to it! The review manager. --Lorenzo

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Using single-pass ranges.
by Robert Jones 03 Aug '12

03 Aug '12

I have a class that hands out a sequence of Things through a getNextThing() interface, ie., struct Thing { }; struct ThingFeed { Thing * getNextThing( ); }; returning null when there's no more things. I'd like to be able to feed this into the Boost range-based algorithms, something like boost::for_each( thingFeedProxy | filter( someCondition ), doSomething ); But it's not clear to me how or if I can represent my ThingFeed as a range. Any thoughts or advice appreciated. Thx, Rob

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linker error
by Kraus Philipp 03 Aug '12

03 Aug '12

Hello, I have got some problems with linking some Boost libraries (1.50) on OSX The linker shows: boost::detail::sp_counted_impl_p<boost::exception_detail::clone_impl<boost::exception_detail::bad_alloc_> >::~sp_counted_impl_p()in test.o boost::detail::sp_counted_impl_p<boost::exception_detail::clone_impl<boost::exception_detail::bad_exception_> >::~sp_counted_impl_p()in test.o boost::system::error_category::~error_category()in test.o boost::detail::sp_counted_base::~sp_counted_base()in test.o boost::exception_detail::clone_base::~clone_base()in test.o boost::exception_detail::clone_impl<boost::exception_detail::bad_exception_>::clone() constin test.o boost::exception_detail::clone_impl<boost::exception_detail::bad_exception_>::~clone_impl()in test.o boost::system::system_error::~system_error()in test.o boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::thread_resource_error> >::~clone_impl()in test.o boost::thread_exception::~thread_exception()in test.o boost::thread_resource_error::~thread_resource_error()in test.o boost::exception_detail::bad_exception_::~bad_exception_()in test.o and with ASIO "std::basic_streambuf<char, std::char_traits<char> >::pbackfail(int)", referenced from: vtable for boost::asio::basic_streambuf<std::allocator<char> >in twitter.o vtable for boost::iostreams::detail::linked_streambuf<char, std::char_traits<char> >in twitter.o vtable for boost::re_detail::parser_buf<char, std::char_traits<char> >in twitter.o "std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long)", referenced from I', using boost thread, iostreams, filesystem, exception an aiso. The exception library is linked with the static option, other dynamic. Which is the correct order to solve the dependency error? Can anybody help me to solve this problem? Thanks Phil

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Announce: Boost 1.50 installer for 32-bit Windows now available
by John Wiegley 01 Aug '12

01 Aug '12

With apologies to the community for not finding the time to release Windows installers for 1.48 and 1.49, we now have an installer for 1.50 available for immediate download: http://www.boostpro.com/download The version installs 32-bit libraries and/or DLLs for the following compilers: Visual C++ 8.0 (Visual Studio 2005) Visual C++ 9.0 (Visual Studio 2008) Visual C++ 10.0 (Visual Studio 2010) We are dropping support for Visual C++ 7.1 as of this time, unless someone wishes to contract us to bring it back. Also, although I have prepared a 64-bit installer, I have not yet found a solution for integrating it with the existing installer. If anyone with NSIS scripting experience would be willing to assist me, we'd be happy to provide a free installer which installs both 32-bit and 64-bit Boost libraries for applicable Windows platforms. Enjoy! -- John Wiegley BoostPro Computing Software Development Training http://www.boostpro.com Clang/LLVM/EDG Compilers C++ Boost

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[fusion] for_each with indices
by Agustín K-ballo Bergé 01 Aug '12

01 Aug '12

I recently needed to iterate over a fusion sequence, calling a function for each element that depends not only on the element type but on its index (position within the sequence) as well. I didn't find anything readily available to use in conjunction with for_each, so I ended up using fold with the index as state. However, I would like to get the index as a compile time value. What would be the simpler/best way to do this? Creating an iterator adaptor that keeps track of advances to the base iterator (should I be using the iterator_facade extension mechanism)? Or perhaps zipping the sequence with some kind of infinite mpl::vector_c sequence? Agustín K-ballo Bergé.- http://fusionfenix.com

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Segfault when using date_time
by Sara Siegal 01 Aug '12

01 Aug '12

I attempted to rebuild my Boost installation with nanosecond support for the date-time library. I did so by adding BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG = 1 ; to boost-build.jam and adding <define>BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG to the jamfile in date_time/build. However, when I add this code to my application and compile, it segfaults: boost::posix_time::time_duration time1, time2; time1=boost::posix_time::seconds(3); std::cout << boost::posix_time::to_simple_string(time1) << std::endl; time2=boost::posix_time::nanoseconds(987654321); std::cout << boost::posix_time::to_simple_string(time2) << std::endl; boost::this_thread::sleep(time2); The segfault is at /archive/home/ssiegal/test/include/boost/date_time/posix_time/posix_time_config.hpp:99: (gdb) list 94 { 95 typedef gregorian::date date_type; 96 typedef time_duration time_duration_type; 97 simple_time_rep(date_type d, time_duration_type tod) : 98 day(d), 99 time_of_day(tod) 100 { 101 // make sure we have sane values for date & time 102 if(!day.is_special() && !time_of_day.is_special()){ 103 if(time_of_day >= time_duration_type(24,0,0)) { Anyone else ever see this? Is there anything else I need to do to turn on nanosecond resolution? Thanks very much!

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[boost] [type_erasure] Review ends today July 27, 2012
by Lorenzo Caminiti 01 Aug '12

01 Aug '12

Hello all, On Mon, Jul 23, 2012 at 9:09 AM, Lorenzo Caminiti <lorcaminiti(a)gmail.com> wrote: > On Wed, Jul 18, 2012 at 1:13 AM, Lorenzo Caminiti <lorcaminiti(a)gmail.com> wrote: >> *** The review of Steven Watanabe's proposed Boost.TypeErasure library >> begins on July 18, 2012 and ends on July 27, 2012. *** > > *** Boost.TypeErasure review ends in 5 days. Please submit your reviews :D *** *** Boost.TypeErasure review ends today July 27, 2012. If you are planning to submit a review, please do so as soon as possible. *** Thank you to everyone who has commented on the library and submitted a review so far! The review manager, --Lorenzo P.S. I am considering extending the review until end of day Sunday July 29, 2012... I will keep you posted. > There have been interesting discussions on the library on the ML but I > have not received any official review yet :( Especially if you are a > user of Boost Any, Function, and Any Iterator, you definitely want to > take a look at Type Erasure as it generalizes solutions provided by > those other libraries. > > Thank you. > > The review manager. > --Lorenzo > >> THE LIBRARY >> >> C++ provides runtime polymorphism through virtual functions. They are >> a very useful feature, but they do have some limitations. >> * They are intrusive. In generic programming, we can design an >> interface which allows third-party types to be adapted to it. >> * They require dynamic memory management. Of course, most of the >> problems can be avoided by using an appropriate smart pointer type. >> Even so, it still acts like a pointer rather than a value. >> * Virtual functions' ability to apply multiple independent concepts to >> a single object is limited. >> The Boost.TypeErasure library solves these problems allowing us to >> mirror static generic programming at runtime. >> >> Library source: >> http://svn.boost.org/svn/boost/sandbox/type_erasure/ >> >> Pre-built documentation: >> http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure/ >> >> You can also download archives with pre-built documentation from: >> http://sourceforge.net/projects/steven-watanabe.u/files/ >> >> YOUR REVIEW >> >> Please submit a review to the mailing-list by replying to this email >> ("[boost] [type_erasure] Review ..." should be in the subject). >> >> Please state clearly whether you think this library should be accepted >> as a Boost library. >> >> Other questions you may want to consider: >> 1. What is your evaluation of the design? >> 2. What is your evaluation of the implementation? >> 3. What is your evaluation of the documentation? >> 4. What is your evaluation of the potential usefulness of the library? >> 5. Did you try to use the library? With what compiler? Did you have >> any problems? >> 6. How much effort did you put into your evaluation? A glance? A >> quick reading? In-depth study? >> 7. Are you knowledgeable about the problem domain? >> >> Thanks in advance to all who participate in the review discussion -- >> I'm looking forward to it!

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[Boost.Move] Conflict between std::move and boost::move (Boost 1.49.0)
by Jonathan Jones 01 Aug '12

01 Aug '12

Hi folks, Consider the following code (which distilled from a real world example): #include <boost/move/move.hpp> #include <boost/optional/optional.hpp> #include <utility> #include <vector> typedef boost::optional<int> data_type; typedef std::vector<data_type> vector_type; vector_type func() { vector_type vv; return move(vv); } If I compile this code using Boost 1.49 on Visual Studio 2010, or on a recent version of g++ (e.g. 4.7.1) which supports some C++11 features, the code fails to compile, complaining about ambiguity between std::move and boost::move. Strangely, the code compiles fine with Apple Clang version 3.1. Is there a way to work around the compilation problem which doesn't involve explicitly qualifying the calls to move? I'd prefer to use argument-dependent-lookup. Removing the includes of boost/move.hpp is not possible. In the real world example, that header is included indirectly. I did notice that if I define the macro BOOST_MOVE_USE_STANDARD_LIBRARY_MOVE, the compilation errors disappear. Is this the correct approach for compilers which support std::move? I find it odd that this macro isn't already defined for such compilers. Thanks in advance! Jon

5 4

accumulators: not copying doubles into the acc set
by MM 01 Aug '12

01 Aug '12

Hello, Having a list of doubles stored somewhere, is there a way not to copy the doubles into the accumulator set and just iterate somehow through the existing data in order to save memory. Imagine I have a std::vector<double> with 10million entries. Then pushing each double to the accumulator set object, then I'd imagine, at one point, the process would hold the 10 million doubles twice. Rds, MM

3 3

[context / coroutine] linker errors
by Szymon Gatner 31 Jul '12

31 Jul '12

I grabbed coroutine lib from http://olk.bplaced.net/boost-coroutine.zip and I am getting linker errors with VC2008 SP1 when trying to compile simplest example from coroutine's documentation: Error 1 error LNK2019: unresolved external symbol _jump_fcontext referenced in function "public: int __thiscall boost::coro::detail::context_base<void __cdecl(void),class boost::ctx::stack_allocator,void,0>::native_start(void)" (?native_start@?$context_base@$$A6AXXZVstack_allocator@ctx@boost@@X$0A@@detail@coro@boost@@QAEHXZ) main_2.obj context Error 2 error LNK2019: unresolved external symbol _make_fcontext referenced in function "public: __thiscall boost::coro::detail::context_base<void __cdecl(void),class boost::ctx::stack_allocator,void,0>::context_base<void __cdecl(void),class boost::ctx::stack_allocator,void,0>(class boost::ctx::stack_allocator const &,unsigned int,enum boost::coro::flag_unwind_t,bool)" (??0?$context_base@$$A6AXXZVstack_allocator@ctx@boost@@X$0A@@detail@coro@boost@@QAE@ABVstack_allocator@ctx@3@IW4flag_unwind_t@23@_N@Z) main_2.obj context btw, old documentation link (http://ok73.ok.funpic.de/boost/libs/context/doc/html/) for boost.context does not work anymore and I remember it had continuation example which is not included in library examples. Any way to get it back? -- Szymon Gatner The Lordz Games Studio www.thelordzgamesstudio.com

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