November 2013 - Boost-users - lists.preview.boost.org

Converting Timestamp into hex of 8 bytes
by Rahul Mathur 09 Nov '13

09 Nov '13

Sorry for wrong post. I have a string Timestamp of 1383889129 which on ONLINE conversion from string to hex gives a 10 bytes as "31 33 38 33 38 38 39 31 32 39". But, the need is to have the TIMEStamp in 8 bytes only. OR any other way using either C++ or Boost where I can convert the string Timestamp of 1383889129 into 8 bytes hex value. Any clue ..!!

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Handling JSON with Boost
by Jauhien Piatlicki 07 Nov '13

07 Nov '13

Hi all, I'm interested whether there exists a library for working with JSON in Boost that preserves data types? I know about property_tree, but if I read a valid JSON with it and then write it out it results in all fields being strings. This is because property_tree internally does not distinguish different value types. But I need something that can read e.g. {"number":42} get access to it and write it then in the same form. Thanks for answering, regards, Jauhien

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Boost API System or Library Calls ..
by Rahul Mathur 06 Nov '13

06 Nov '13

Out of curiosity, wish to know if BOOST ASIO calls like - boost::asio::read() boost::asio::transfer_all() boost::asio::write() BOOST LEXICAL calls like - boost::lexical_cast<std::string>() BOOST POSIX TIME calls like - boost::posix_time::microsec_clock::universal_time() boost::posix_time::microsec_clock::ptime() are LIBRARY or SYSTEM calls. How to know which calls of BOOST are SYSTEM and LIBRARY calls? Thanks.

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Safe to pass dereferenced anonymous shared_ptr?
by Chris Stankevitz 06 Nov '13

06 Nov '13

Q1: Is the below code dangerous? A1: Only if the anonymous shared_ptr is deleted before function f returns. Q2: Is the anonymous shared_ptr deleted before function f returns? A2: ? Thank you, Chris === #include <iostream> #include <boost/make_shared.hpp> void f(const int& i) { std::cout << "i = " << i << std::endl; } int main() { f(*boost::make_shared<int>(42)); return 0; }

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[Containter] Compilation errors with 1.55 and VC2013
by Szymon Gatner 05 Nov '13

05 Nov '13

Hi, I am getting compilation errors with Container library after trying to build with Visual Studio 2013 and Boost 1.55 RC: Error 1 error C2228: left of '.select_on_container_copy_construction' must have class/struct/union c:\devel\boost_1_55_0\boost\intrusive\detail\has_member_function_callable_with.hpp 200 1 ConsoleApplication2 Minimalistic example to reproduce: #include <boost/signals2/connection.hpp> #include <boost/container/slist.hpp> #include <boost/container/vector.hpp> int main() { typedef boost::signals2::connection Connection; boost::container::vector<Connection> connections_; } Error happens wheter vector or slist is used (didn't try more containers) Regards, Szymon Gatner

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[LOG]: set_filter error in tutorial_filtering.cpp and per-sink instance filtering
by Johan Lundberg 05 Nov '13

05 Nov '13

Dear all, (this is my first post to this list) I'm trying to make a boost log sink that would filter on a severity level which should be thread-safely modifiable while logging is ongoing. On my way there I get errors while trying to compile this tutorial example: http://www.boost.org/doc/libs/1_54_0/libs/log/example/doc/tutorial_filterin… The file as-is compiles and runs fine, but if I switch on the user-provided filtering function example by activating the block in #if 0 (and commenting out the other definition of init()) I get errors related to phoenix bind: The offending line is 155: sink->set_filter(phoenix::bind(&my_filter, severity, tag_attr)); I would be grateful for advice on how to get that working. More details on that at the end of the mail. Now, assuming I get past the errors, what is a good way to add a per-sink log level filter? I may have several instances of the sink. To clarify: I know this is not the right syntax, but If I could use a custom functor or a C++11 lambda for a filter I would do something like this: using ATseverity=std::atomic<severity_level> ; // (severity is an enum) shared_ptr<ATseverity> shared_log_level = std::make_shared<ATseverity>(warning); sink->set_filter( [=shared_log_level]->bool(severity_level const& level, std::string const& tag){ return level >= shared_log_level->get(); }); I could then store and modify the shared_log_level from elsewhere. Is there a right way to do this? cheers /Johan Details on the compilation error: I think this is the relevant part of the error message: /myboost154/include/boost/phoenix/core/preprocessed/expression_10.hpp:140:17: error: could not convert ‘boost::proto::make_expr<boost::phoenix::detail::tag::function_eval, boost::proto::domainns_::basic_default_domain, boost::phoenix::detail::function_ptr<2, bool, bool (*)(const boost::log::v2_mt_posix::value_ref<severity_level>&, const boost::log::v2_mt_posix::value_ref<std::basic_string<char> >&)>, boost::log::v2_mt_posix::expressions::attribute_keyword<tag::severity>, boost::log::v2_mt_posix::expressions::attribute_keyword<tag::tag_attr> >((* & a0), (* & a1), (* & a2))’ from ‘const type {aka const boost::proto::exprns_::basic_expr<boost::phoenix::detail::tag::function_eval, boost::proto::argsns_::list3<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::function_ptr<2,bool, bool (*)(const boost::log::v2_mt_posix::value_ref<severity_level>&, const boost::log::v2_mt_posix::value_ref<std::basic_string<char>>&)> >, 0l>, boost::log::v2_mt_posix::expressions::attribute_keyword<tag::severity>, boost::log::v2_mt_posix::expressions::attribute_keyword<tag::tag_attr> >, 3l>}’ to ‘boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::detail::function_ptr<2, bool, bool (*)(const boost::log::v2_mt_posix::value_ref<severity_level>&, const boost::log::v2_mt_posix::value_ref<std::basic_string<char> >&)> >, 0l>::proto_child0 { aka boost::phoenix::detail::function_ptr<2, bool, bool (*)(const boost::log::v2_mt_posix::value_ref<severity_level>&, const boost::log::v2_mt_posix::value_ref<std::basic_string<char> >&)>}’ }; I tried boost 1.54 and compiled with gcc 4.7.1 and 4.8.1 under Linux, with and without C++11 mode: g++ -std=gnu++11 -DBOOST_ALL_DYN_LINK boostlogexample.cpp -L $BOOST/lib/ -I $BOOST/include/ -pthread -lboost_system -lboost_log_setup -lboost_log \ -lboost_date_time -lboost_thread -lrt -lboost_filesystem

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container with large number of elements and a small number of invalide elements
by MM 05 Nov '13

05 Nov '13

Hello, I have a need for a container where I can store 10^6 elements of type T (PODs) , a small number of which (say 100) can be invalid elements (ie special value of T) The 100 elements can be randomly distributed throughout the 10^6 elements. The container should be as close to a sequence container as possible. The required usages: 0. invalid elements can be set = 10^6 - 100 1. get number of valid elements in O(1) 2. get the max/min element of all valid elements 3. have a bidrectional iterator that iterators only over valid elements On a separate note, is there a version of multi_array where the number of dimensions is known at runtime? regards,

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[1.55.0] Release candidate 2 available
by Marshall Clow 05 Nov '13

05 Nov '13

RC2 files for 1.55.0 are available at http://boost.cowic.de/rc/ 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: 93780777cfbf999a600f62883bd54b17 *boost_1_55_0_rc2.tar.gz d6eef4b4cacb2183f2bf265a5a03a354 *boost_1_55_0_rc2.tar.bz2 8aca361a4713a1f491b0a5e33fee0f1f *boost_1_55_0_rc2.zip 4e5bbc15fc8c80df8be428f8a5b5a823 *boost_1_55_0_rc2.7z Thanks! -- The release managers === Changes to release since rc1 === ---- Author: bemandawes Date: 2013-10-28 13:16:50 EDT (Mon, 28 Oct 2013) New Revision: 86503 URL: http://svn.boost.org/trac/boost/changeset/86503 Log: Merge 86426 from trunk. This should fix msvc test failures. ---- Author: bemandawes Date: 2013-10-29 09:15:03 EDT (Tue, 29 Oct 2013) New Revision: 86514 URL: http://svn.boost.org/trac/boost/changeset/86514 Log: Merge 84443 from trunk, to fix mpl assert failures for msvc in many libraries. ---- Author: eric_niebler Date: 2013-10-29 12:53:08 EDT (Tue, 29 Oct 2013) New Revision: 86516 URL: http://svn.boost.org/trac/boost/changeset/86516 Log: merge [86460] from trunk, fix bootstrap on mingw --- Author: jhunold Date: 2013-10-29 13:19:33 EDT (Tue, 29 Oct 2013) New Revision: 86519 URL: http://svn.boost.org/trac/boost/changeset/86519 Log: Merge 84402 from ^/trunk ------------------------------------------------------------------------ r84402 | jhunold | 2013-05-21 14:23:20 +0200 (Di, 21 Mai 2013) | 4 lines Fix: cache file loading and saving must use native paths Fixes caching at least on Windows platform ------------------------------------------------------------------------ --- Author: johnmaddock Date: 2013-11-01 05:32:55 EDT (Fri, 01 Nov 2013) New Revision: 86532 URL: http://svn.boost.org/trac/boost/changeset/86532 Log: Merge fix for dependency tracking. --- Author: danieljames Date: 2013-11-03 14:20:09 EST (Sun, 03 Nov 2013) New Revision: 86551 URL: http://svn.boost.org/trac/boost/changeset/86551 Log: Merge Visual C++ 12 fix for Unordered. --- Author: viboes Date: 2013-11-03 15:43:42 EST (Sun, 03 Nov 2013) New Revision: 86552 URL: http://svn.boost.org/trac/boost/changeset/86552 Log: Thread: merge [86540] to fix #9319.

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boost::statechart "custom::reaction"
by rahul baruah 05 Nov '13

05 Nov '13

I am using boost::statechart. Instead of simple_state , using boost:: statechart::state. Now i am able to access the state_machine member variable. but when i am using custom::reaction or mpl::list it throught error. Code Snippet: struct NotReady : StateBase< NotReady, TopState > { //typedef NotReadyStateList reactions; NotReady (my_context ctx) : my_base( ctx ){ outermost_context().maxPairedDevices = 3; cout << outermost_context().maxPairedDevices << endl; } template< class MostDerived > sc::result react( const PairingBaseEvents< MostDerived > & ); public: typedef sc::custom_reaction< StartEvent > reactions; }; Error: ndefined reference to `boost::statechart::detail::safe_reaction_result NotReady::react<StartEvent>(PairingBaseEvents<StartEvent> const&)' regards Rahul Baruah

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Concatenating int value to string ..??
by Rahul Mathur 05 Nov '13

05 Nov '13

All, I wish to have string (combination of string value and int value) which increments until 100. The code is as below - --- #include <iostream> #include <cstdlib> #include <string> #include <boost/lexical_cast.hpp> using namespace std; int main() { std::string TID = "Apple"; int TagID = 01, Value = 000 /* 100 IDs*/; std::string TagName, TagInitial, TagUId; TagName = TID + boost::lexical_cast<std::string>(TagID); // Should be as -> Apple01 TagInitial = TagName + boost::lexical_cast<std::string>(Value); // Should be as -> Apple01000 int i = boost::lexical_cast<int>(TagInitial) + 1; // Should be as -> Apple01001 TagUId = boost::lexical_cast<std::string>(i); std::cout << "Tag ID .." << TagUId << endl; } I get below error message - -- terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::bad_lexical_cast> >' what(): bad lexical cast: source type value could not be interpreted as target Aborted (core dumped) -- Any clue? ~ Thanks!!

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