December 2015 - Boost-users - lists.preview.boost.org

boost program_options
by avib369 . 06 Jan '16

06 Jan '16

There seems to be change/regression in boost program options. In boost/1.53. I used boost::program_options::variables_map vm; po::store( po::parse_command_line( argc, argv, desc_ , po::command_line_style::unix_style ^ po::command_line_style::allow_short), vm ); po::notify( vm ); This could handle arguments like: ./exe --help all ./exe --help summary However from boost 1.59, this no longer works, instead I have to use: ./exe --help=all ./exe --help=summary Is this a known change ? how do i get back to the old functionality ? Ta, Avi

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[regex] link errors on 1.60 update
by James Walker 06 Jan '16

06 Jan '16

When I tried to convert my project from Boost 1.58.0 to 1.60.0, I got some link errors. This is using Xcode 4.6.3 on Mac OS X 10.7.5. I'm compiling all the sources in libs/regex/src. Help? Undefined symbols for architecture i386: "boost::re_detail_106000::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::construct_init(boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags)", referenced from: boost::re_detail_106000::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::perl_matcher(char const*, char const*, boost::match_results<char const*, std::allocator<boost::sub_match<char const*> > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags, char const*) in BVHJointMap.o boost::re_detail_106000::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::perl_matcher(char const*, char const*, boost::match_results<char const*, std::allocator<boost::sub_match<char const*> > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags, char const*) in AnimationsManager.o "boost::re_detail_106000::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::find()", referenced from: bool boost::regex_search<char const*, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(char const*, char const*, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags) in BVHJointMap.o "boost::re_detail_106000::perl_matcher<char const*, std::allocator<boost::sub_match<char const*> >, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::match()", referenced from: bool boost::regex_match<char const*, std::allocator<boost::sub_match<char const*> >, char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >(char const*, char const*, boost::match_results<char const*, std::allocator<boost::sub_match<char const*> > >&, boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > > const&, boost::regex_constants::_match_flags) in AnimationsManager.o

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Boost 1.60.0 rc1 is now available
by Marshall Clow 05 Jan '16

05 Jan '16

Release candidate files for 1.60.0 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: MD5 (boost_1_60_0_rc1.7z) = 7ce7f5a4e396484da8da6b60d4ed7661 MD5 (boost_1_60_0_rc1.tar.bz2) = 65a840e1a0b13a558ff19eeb2c4f0cbe MD5 (boost_1_60_0_rc1.tar.gz) = 28f58b9a33469388302110562bdf6188 MD5 (boost_1_60_0_rc1.zip) = 0cc5b9cf9ccdf26945b225c7338b4288 Thanks! -- The release managers P.S. Release notes are here: http://www.boost.org/users/history/version_1_60_0.html

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[units] Adding two absolute units
by Itzik 03 Jan '16

03 Jan '16

Hello, <obligatory appreciation on first post> I started using Boost just for boost::units and I find new ways boost can help me almost every day. So thanks for the great stuff! </obligatory appreciation on first post> My question to the board is why two absolute quantities (si::temperature (K) in my case) can't be summed in boost::units? I realized that this is a rule enforced by-design (gmane.comp.lib.boost.user/71747), and I understand that it is probably not a very common case, but I wanted my code to solve a simple formula which requires adding up two absolute temperatures (quantity<absolute<temperature>>). Each temperature represents an Inlet temperature in a Heat Exchange system. So even if converting one temperature to a relative type (quantity<temperature>) might be a workaround, it seems like a forced misuse to me. Eventually it turned out that I was mistaken with the formula, and subtraction was required instead, so there's no problem there. Alas, there's also a much simpler use case: What if I want to average the temperature of the last N readouts? Shouldn't boost::units support this simple operation? I have no formal physics education, but intuitively, adding two absolute temperatures doesn't seem really like a mistake to me, even if it's an odd thing to do. Will appreciate your thoughts on the matter.

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Modifying all matching elements in a Boost.MultiIndex Container
by Amit Prakash Ambasta 01 Jan '16

01 Jan '16

Hi, I am trying to modify members of all elements matching value for a given index in a boost.multiindex container index.modify( index.find(value), [](T& element) { ... } ) seems to update a singular element(first match) On the other hand, std::pair<index::iterator, index::iterator> iter = index.equal_range(value); while(iter.first != iter.second) { index.modify( iter.first, [](T& element) { ... } ); iter.first++; } leads to segfaults and unexpected behavior. What would be right way to approach this?

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Pointer to objects in Boost.MultiIndex
by Amit Prakash Ambasta 01 Jan '16

01 Jan '16

Consider the following code snippet: #include <iostream> #include <boost/multi_index_container.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/member.hpp> using namespace std; using namespace boost::multi_index; struct LinkList; struct LinkList { size_t index; LinkList* parent; LinkList(size_t index, LinkList* parent) : index(index), parent(parent) {} }; struct llindex {}; typedef ordered_unique<tag<llindex>, member<LinkList, size_t, &LinkList::index> > LinkListIndex; typedef boost::multi_index_container<LinkList, indexed_by<LinkListIndex> > IndexedLinkList; template <typename T> void show(T& iterable) { for(auto const& element: iterable) { if(element.parent != nullptr) { std::cout << "Index<" << element.index << ">: " << element.parent->index << std::endl; } else { std::cout << "Index<" << element.index << ">: " << "NULL" << std::endl; } } } int main() { IndexedLinkList ill; auto &index_ll = ill.get<0>(); ill.insert(LinkList{0, nullptr}); ill.insert(LinkList{1, (LinkList*)(&(*index_ll.find(0)))}); ill.insert(LinkList{2, (LinkList*)(&(*index_ll.find(0)))}); ill.insert(LinkList{3, (LinkList*)(&(*index_ll.find(2)))}); show(ill); return 0; } Would (LinkList*)(&(*index__ll.find(value))) be the recommended way to fetch the pointer to parent?

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[Boost.Serialization][Boost.Iterators] Problem with Boost 1.59.0 in Solaris with SunCC
by dariomt＠gmail.com 30 Dec '15

30 Dec '15

Hi all, I have found a problem compiling Boost, in libs/serialization/src/basic_text_oprimitive.cpp the usage of boost::iterator::iterator_facade is problematic. I have reduced it to a two line minimal case: #include <boost/archive/iterators/ostream_iterator.hpp> boost::archive::iterators::ostream_iterator<char> it; Trying to compile this with SunCC 5.10 (Sun Studio 12.1) in Solaris I get the following error: "boost/iterator/iterator_facade.hpp", line 779: Error: value is not a member of boost::iterators::detail::is_traversal_at_least<std::output_iterator_tag, boost::iterators::bidirectional_traversal_tag>. "boost/archive/iterators/ostream_iterator.hpp", line 40: Where: While specializing "boost::iterators::iterator_facade<boost::archive::iterators::ostream_iterator<char>, char, std::output_iterator_tag, boost::archive::iterators::ostream_iterator<char>&, int>". "boost/archive/iterators/ostream_iterator.hpp", line 40: Where: Specialized in boost::archive::iterators::ostream_iterator<char>. "fail.cpp", line 2: Where: Specialized in non-template code. I guess it must be some bug in the compiler, because if I try to instantiate directly the template mentioned in the error message it works fine. (i.e. value is indeed a member). #include <boost/iterator/iterator_facade.hpp> const bool value = boost::iterators::detail::is_traversal_at_least< std::output_iterator_tag, boost::iterators::bidirectional_traversal_tag >::value; For reference, this problem was *not* present in Boost 1.55.0. Thanks! PS: I have mentioned both libraries in the subject because I don't know if this is a problem with Boost.Iterator code, or with the usage of that library from Boost.Serialization.

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[iostreams] Fix for Ticket #11860
by Gagan Kumar 28 Dec '15

28 Dec '15

Bug Ticket ( https://svn.boost.org/trac/boost/ticket/11860 ) says "Using iostreams causes lots of messages about deprecated header template_arity_spec.hpp". Thus to reduce messages about deprecated header, I created a pull request here https://github.com/boostorg/iostreams/pull/24 . Regards Gagan

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Implementation Of Natural Sort for C++
by Gagan Kumar 27 Dec '15

27 Dec '15

In Boost Trac, I found Natural Sort as Ticket #11021 (new Feature Requests). I too think it will be good for C++ to have it too. Thus I tried to make my Implementation on Natural Sort. Here, https://github.com/scopeInfinity/NaturalSort Can this be included in Boost extensions, or can you please guide me to make it better so that It can be included. Regards Gagan Kumar Natural Sort Example - Inputs : Hello 100 Hello 34 Hello 9 Hello 25 Hello 10 Hello 8 Normal Sort Output : Hello 10 Hello 100 Hello 25 Hello 34 Hello 8 Hello 9 Natural Sort Output : Hello 8 Hello 9 Hello 10 Hello 25 Hello 34 Hello 100 | | | | | | | | | | | scopeInfinity/NaturalSortNaturalSort - C++ Implementation of Natural Comparision and Natural Sort | | | | View on github.com | Preview by Yahoo | | | | |

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[multi_index] do erase() call key extractors?
by Nick Stokes 25 Dec '15

25 Dec '15

This is probably rather obvious, but I wasn't able to locate this guarantee in MIC docs. Take, struct Foo { explicit Foo(Bar* b = nullptr) : bar(b) {} Bar* bar; }; int getBarValue (const Foo& f) { assert( f.bar ); return f.bar->getValue(); } boost::multi_index< Foo, indexed_by< < hashed_unique < member<Foo, Bar* , &Foo::bar > >> , hashed_non_unique < global_fun<const Foo&, int, &getBarValue >> >> FooIndex; void grill() { FooIndex fooIndex; Bar* b; { auto bWork = make_unique<Bar>(); // ... fooIndex.emplace( bWork.get() ); b = bWork.get(); } fooIndex.erase(b); // ... } Please ignore the fact that raw-pointers are potentially dangerous etc. The question is does erase() call getBarValue() despite the fact I am using the first index? More generally, do key extractors get called *at all* except at the point of insertion? Thanks, Nick

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