April 2015 - Boost-users - lists.boost.org

[multi_index] Announcing preview of ranked indices
by Joaquin M Lopez Munoz 22 Apr '15

22 Apr '15

Hi, It's been 11 years since first proposed, but here it is at last. I'm releasing a prereview of ranked indices for Boost.MultiIndex: struct person { int age; std::string name; }; typedef multi_index_container< person, indexed_by< ranked_non_unique<member<person,int,&person::age> >, ordered_non_unique<member<person,std::string,&person::name>>>> multi_t; multi_t m={{40,"Joe"},{25,"Jill"},{30,"Kurt"},{32,"Sue"}}; auto it=m.emplace(31,"Maggie").first; std::cout<<m.rank(it)<<" persons younger than "<<it->name<<"\n"; auto n=m.size()/2; std::cout<<n<<" persons are less than "<<m.nth(n)->age<<" years old\n"; Ranked indices add a bunch of extra rank-related capabilities to the interface of ordered indices. The rank of an element is its numerical position in the index. nth(i) returns an iterator to the element with rank i, whereas rank(it) is the inverse operation. Both execute in log(n) time. Additionally, the member functions find_rank lower_bound_rank upper_bound_rank equal_range_rank range_rank behave as their "_rank"-less counterparts except they return ranks rather than iterators. One drawback of ranked indices wrt ordered indices (other than their slower perfomance and higher memory consumption) is that deletion of elements is log(n) (in ordered indices it is constant time). Download lib preview: http://tinyurl.com/kemwk8q Tutorial: http://tinyurl.com/q36c9f7 Reference: http://tinyurl.com/pvoulgr For people interested in this, I'd appreciate if you could download the source, copy it on top of Boost 1.58 (1.57 should work as well), play a bit with the new feature and report your results. Also, opinions on naming are welcome. Target version for releasing is Boost 1.59, so we have plenty of time to discuss the design before it is final. Thank you, Joaquín M López Muñoz Telefónica

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Which is the effective way for data transfer for Interprocess shared memory ?
by Kalyan Chakravarthy Gudimella 22 Apr '15

22 Apr '15

Hi, I am currently evaluating boost interprocess library for using shared memory. I found two ways to transfer complex data structures. 1. Creating data structures directly in shared memory. E.g. http://www.boost.org/doc/libs/1_58_0/doc/html/interprocess/allocators_conta… class complex_data{ int id_; char_string char_string_; int_vector_vector int_vector_vector_; public: //Since void_allocator is convertible to any other allocator<T>, we can simplify //the initialization taking just one allocator for all inner containers. complex_data(int id, const char *name, const void_allocator &void_alloc) : id_(id), char_string_(name, void_alloc), int_vector_vector_(void_alloc) {} //Other members...}; 2. Serializing data into bufferstream and deserializing it. E.g.http://www.boost.org/doc/libs/1_58_0/doc/html/interprocess/streams.html My initial trial shows that streaming to bufferstream took 7 times more time than using direct shared structures. Can you please help me to choose the effective way between these two approaches? thanks, Kalyan

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[MPL][Config] Can no longer pre-generate headers for MPL-containers with more than 50 elements.
by Deniz Bahadir 22 Apr '15

22 Apr '15

Hello everyone, While playing around with the current Boost release-candidate (1.58.0-RC3) I noticed that pre-generating MPL-headers for MPL-containers with more than 50 Elements seems no longer possible. Up till at least Boost 1.55.0 I was able to pre-generate these MPL-headers using the python-scripts from Boost-source ([1]) with the help of a bash-script which I already described here [2]. Internally, these python-scripts seem to use GCC to generate these MPL-headers. They also seem to partially circumvent Boost.Config by using custom user.hpp files located in subdirectories of [3] and defining BOOST_NO_CONFIG and some other macros therein. However, this does not seem to please Boost.Config so that compiler-errors ([4]) occur. Defining the macro BOOST_CONFIG_ALLOW_DEPRECATED as [4] suggests seems not to help. It just silences the warnings but does not generate proper files. (It actually erases the content of almost all header-files in subdirectories of [5].) Does anyone know how to workaround or better fix this? Or does anyone know who to talk to, to get these problems fixed? Also, I would suggest, that documentation for these python-scripts are added to the documentation of Boost.MPL. Best regards, Deniz References: [1] ${BOOST_SOURCE}/libs/mpl/preprocessed/ [2] http://stackoverflow.com/a/20660264/3115457 [3] ${BOOST_SOURCE}/libs/mpl/preprocessed/include/ [4] #error "You are using a compiler which lacks features which are now a minimum requirement in order to use Boost, define BOOST_CONFIG_ALLOW_DEPRECATED if you want to continue at your own risk!!!" [5] ${BOOST_SOURCE}/boost/mpl/aux_/preprocessed/

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[SPAM] from: giridhar
by giridhar 22 Apr '15

22 Apr '15

Greetings boost http://findislamicservices.com/reduce.php?silver=aswydt7xv2r0enm3 giridhar Sent from my iPhone

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sliding window containing n seconds of data
by Lane 22 Apr '15

22 Apr '15

I'm looking for a way to examine an array of object structures for an adjustable window of n seconds. My application reads objects at a high rate (which I'll have to throttle), and I'd then like to put them onto an array. My thinking is to assign a timer on each object that is initialized to n seconds and once the timer expires, the object is removed from the array, but while it's on the array, I'll iterate over the objects looking for the info I need. I put this out on the boost list as I suspect boost has the mechanisms to handle this and someone could suggest a good way of going about it. Any help much appreciated.

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1.58.0 rc3 is now available
by Marshall Clow 22 Apr '15

22 Apr '15

Release candidate files for 1.58.0 are available at: http://boost.cowic.de/rc/ * Since rc1, the changes that were causing the serialization libraries to fail to build on MSVC have been reverted. * Since rc2, the documentation for bind, and mem_fun. No code changes. As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. This helps ensure the candidates build OK before we push them out to SourceForge. The files (and associated md5s) are: MD5 (boost_1_58_0_rc3.7z) = f7255aeb692c1c38fe761c32fb0d3ecd MD5 (boost_1_58_0_rc3.tar.bz2) = b8839650e61e9c1c0a89f371dd475546 MD5 (boost_1_58_0_rc3.tar.gz) = 5a5d5614d9a07672e1ab2a250b5defc5 MD5 (boost_1_58_0_rc3.zip) = b0605a9323f1e960f7434dbbd95a7a5c Thanks! -- The release managers P.S. Release notes are here: http://www.boost.org/users/history/version_1_58_0.html

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Re: [Boost-users] [IPC Named Mutex]
by Lorenzo Trivelli 21 Apr '15

21 Apr '15

Hi Tom, I tried your solution and it worked, and I'm stil wondering about the rationale behind the bootup time usage ;-) I also submitted a bug ticket, #11194, but track took a very long time to create it and add the test case, and in the end I found that: 1) a bug with ticket !11195 was also created 2) the test case was attached four times :-( can anyone please clean it up as is is a quite ugly ? ;-) regards Lorenzo

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Re: [Boost-users] [Serialization / 1.58] wrong number of entries in std::vector<boost::tuple<double, double, double> >
by Rüdiger Berlich 21 Apr '15

21 Apr '15

Hi Robert, I have submitted trac item 11214 and attached the test case. The trac web interface somehow froze for me upon submission (Safari / MacOS), and I apparently have pressed the submit button more than once, trying to submit the track item. So it appears as if more than one ticket has been created (11215 - 11218), which I do not seem to be able to delete. Please ignore these -- apologies. Best Regards, Beet > > ouch! - make a trac item for this! > > Robert Ramey > > > > -- > View this message in context: http://boost.2283326.n4.nabble.com/Serialization-1-58-wrong-number-of-entri… > Sent from the Boost - Users mailing list archive at Nabble.com. > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users >

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Web doc 1.58 Categorized error
by Larry 20 Apr '15

20 Apr '15

I tried to look at the 1.58 doc on the website and clicking on Categorized gave me under the headings By Category Unknown category: Data structures Apparently missing something. “All”, “Standard Proposals” etc seem to work. Larry

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[Serialization / 1.58] wrong number of entries in std::vector<boost::tuple<double, double, double> >
by Rüdiger Berlich 20 Apr '15

20 Apr '15

Hi, I’ve just installed Boost 1.58 and ran into the following problem: I have a class with a std::vector<boost::tuple<double, double, double> >, that is supposed to always have at least one entry, but may have more. Hence, in the default constructor, I initialize the std::vector with one entry. The class is also serializable. Up until Boost 1.57, a de-serialized object always had the correct number of entries in the vector. As of 1.58, I am getting one entry too much, which probably means that Boost.Serialization simply attaches entries to the vector of a default-constructed class, but doesn’t clear it first. This happens in C++11-Mode, both on Ubuntu 14.10 (gcc 4.9.1) as well as on MacOS X Yosemite . It DOES NOT happen with a std::vector<double> . Below is a full test case that replicates the problem in a simplified environment. For Boost 1.57 the program returns: t_vec.size() = 1 t_vec2.size() = 1 For Boost 1.58 the answer is t_vec.size() = 1 t_vec2.size() = 2 Best Regards, Beet /******************************************************/ #include <boost/archive/xml_oarchive.hpp> #include <boost/archive/xml_iarchive.hpp> #include <boost/serialization/nvp.hpp> #include <boost/serialization/vector.hpp> #include <boost/tuple/tuple.hpp> #include <iostream> #include <vector> #include <sstream> namespace boost { namespace serialization { template<typename archive, typename T0, typename T1, typename T2> void serialize(archive & ar, boost::tuple<T0, T1, T2> & tpl, unsigned int) { using namespace boost; using boost::serialization::make_nvp; ar & make_nvp("tpl_0", boost::get<0>(tpl)) & make_nvp("tpl_1", boost::get<1>(tpl)) & make_nvp("tpl_2", boost::get<2>(tpl)); } } /* namespace serialization */ } /* namespace boost */ int main() { std::vector<boost::tuple<double, double, double> > t_vec, t_vec2(1); std::ostringstream oss; t_vec.push_back(boost::tuple<double, double, double>(1.,2.,3.)); std::cout << "t_vec.size() = " << t_vec.size() << std::endl; // save data to archive { boost::archive::xml_oarchive oa(oss); // write class instance to archive oa & BOOST_SERIALIZATION_NVP(t_vec); // archive and stream closed when destructors are called // Data is now in oss } // load data from archive { std::istringstream iss(oss.str()); boost::archive::xml_iarchive ia(iss); // read class state from archive ia & BOOST_SERIALIZATION_NVP(t_vec2); // archive and stream closed when destructors are called } std::cout << "t_vec2.size() = " << t_vec2.size() << std::endl; }

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