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[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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boost fusion dynamic at_n
by Niitsuma Hirotaka 04 Aug '12

04 Aug '12

I made boost fusion dynamic at_n usage boost::fusion::vector<int,double,std::string,char> vec(9 ,2.2 ,"aaa" ,'b'); std::cout << at_n_dynamic<double>(vec, 1) << std::endl; //=> 2.2 detail http://d.hatena.ne.jp/niitsuma/20120803/1343979718

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How to create array of boost::interprocess::interprocess_mutex in maped file
by Alan Bus 04 Aug '12

04 Aug '12

I think here may be the good place to get some help or instruction. So I post my question here. Thanks in advance. I'd like to create array interprocess_mutex in mapped file, but don't know how to do that. Could you give some hints are highly appreciated? Thanks in advance! Following is my code snippet, typedef boost::interprocess::interprocess_mutex TMutex; managed_mapped_file *pMapFile = new managed_mapped_file(open_or_create, "/tmp/test.bin",1024UL*64UL*4096UL); TMutex *pMutex = pMapFile->construct<TMutex>("MyMutex")[50](); // Not sure here is right or not? TMutex **? How to declare for mutex array? //If I'd like to refer to 2nd element of this array, how can I use it? //pMutex[2] ? for example, scoped_lock<TMutex> lock<pMutex[2]>; // it crashed Could you give some instruction on how to create mutex array and how to access it by [] or other ways? Thank you very much. -- sincerely, Alan

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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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Connecting signals2::signal to another signals2::signal: trackable?
by Chris Stankevitz 03 Aug '12

03 Aug '12

class A { boost::signals2::signal<void()> Signal; } class B { boost::signals2::signal<void()> Signal; } boost::shared_ptr<A> pA = boost::make_shared<A>(); boost::shared_ptr<B> pB = boost::make_shared<B>(); === Q1: Is it possible to connect A's signal to B? A1: Yes: void f() { pA->Signal.connect(pB->Signal); pA->Signal(); } === Q2: Will I get a crash if pB is subsequently released? A2: Yes void f() { pA->Signal.connect(pB->Signal); pB.reset(); pA->Signal(); // crash! } === Q3: Is it possible to use signals2::signal::slot_type::track to avoid the crash? A3: [I do not know the answer, please help me here] === Thank you, Chris

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build Boost on OSX with other sysroot
by Kraus Philipp 03 Aug '12

03 Aug '12

Hello, I try to build the Boost 1.50 under OSX (10.6), but I need another sysroot version. Because I need a build with i386 and linking again the /Developer/SDKs/MacOSX10.5.sdk/ Default build again the 10.6 SDK works very well. I have added to the bjam command the flag architecture=x86 and toolset=darwin (--with flags, link, etc), but how can I link the Boost libs to the 10.5 SDK? Thanks Phil

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[fusion] creating fusion-vectors of references
by Oswin Krause 03 Aug '12

03 Aug '12

Hi list, I am new to fusion, so my problem might be really easy to solve. I have a fusion vector which looks a bit like typedef fusion::vector<std::vector<A>,std::vector<B>,std::vector<C> > Tuple; All vectors have the same size and I want from each of these std::vectors one specific element (like the 10th from every vector) and create a fusion::vector<A&,B&,C&> from these elements(my real problem is a bit more complicated, for example one of the vectors might be std::vector<bool>, so the type might be different from an actual reference) My first try was transform: //the Functor which extracts the i-th element class Get { private: std::size_t m_index; public: Get(std::size_t index):m_index(index){} template<typename Sig> struct result; template<typename U> struct result<Get(U&)>{ typedef typename U::reference type; }; template <typename U> typename result<Get(U)&>::type operator()(U& vec) const{ return vec[m_index]; } }; Tuple myTuple(...); fusion::vector<A&,B&,C&> ref = boost::fusion::transform(myTuple,Get(0)); But this doesn't work, because 1. transform only takes myTuple as constant argument. 2. it performs a value-initialization of the references in the constructor, not in the initialization list. Any solution to my problem? It should work for fusion::vector, but a solution which works for all fusion sequences is awarded with bonus points :). If there is no solution for fusion::vector, I would appreciate a solution for another container as well (but no bonus in this case!) Greetings, Oswin

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[boost] [type_erasure] Review ends today Aug 3, 2012
by Lorenzo Caminiti 03 Aug '12

03 Aug '12

Hello all, *** The review of Boost.TypeErasure ends today Aug 3, 2012. If you are planning to submit a review, please do so by the end of today. *** Thank you to all that have participated to the review so far. The review manager, --Lorenzo On Jul 27, 2012 1:41 PM, "Lorenzo Caminiti" <lorcaminiti(a)gmail.com> wrote: > Hello all, > > After consulting the review wizards and Steven, I am extending > Boost.TypeErasure review of one week, until August 3, 2012. > > Thank you to all that have submitted a review already and I am looking > forward to receiving additional submissions. > > The review manager, > --Lorenzo > On Jul 27, 2012 3:22 AM, "Lorenzo Caminiti" <lorcaminiti(a)gmail.com> > wrote: > >> 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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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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boost::graph subgraph + write_graphviz()
by Chris Cooper 03 Aug '12

03 Aug '12

Hi, I'm trying to output an image showing subgraphs [0] using write_graphviz() in boost 1.48.0. I've tried to modify an example [1] by adding a write_graphviz() call. eg... std::ofstream ofs("out.dot"); const char* names[] = { "A", "B", "C", "D", "E", "F" }; write_graphviz(ofs, G0.m_graph, make_label_writer(names)); This works fine for displaying the underlying graph, but no subgraphs are shown. When I do the following... write_graphviz(ofs, G0, make_label_writer(names)); I get a host of errors including... include/boost/graph/graphviz.hpp:377: error: no matching function for call to ‘get(boost::label_writer<const char**>&, Vertex&)’ I notice a comment in graphviz.hpp [2] 'requires graph_name graph property' so I had a look at the subgraph_properties.cpp example [3]. This seemed to only be showing vertex properties but didn't compile out of the box. Is it possible for someone experienced in boost::graph to post a modified version of [1] that can produce something like image [0], or point me in the right direction? Thanks, Chris [0] http://www.boost.org/doc/libs/1_48_0/libs/graph/doc/figs/subgraph.gif [1] http://www.boost.org/doc/libs/1_48_0/libs/graph/example/subgraph.cpp [2] http://www.boost.org/doc/libs/1_48_0/boost/graph/graphviz.hpp [3] http://www.boost.org/doc/libs/1_48_0/libs/graph/example/subgraph_properties…

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