January 2016 - Boost-users - lists.preview.boost.org

[interprocess] Determine size of managed_shared_memory
by Kai Benndorf 12 Oct '19

12 Oct '19

Hi all, I want to create a managed_shared_memory in exactly the size I needed. Therefore I do something like this: size = sizeof( common_managed_shared_memory ); size += sizeof( MyClassInSharedMem ); managed_shared_memory segment(create_only, "name", size ); MyClassInSharedMem allocates itself some memory by segment->allocate(). I added this also to the size, but get a boost::interprocess::bad_alloc exception on allocating this additional memory. Are there some magic bytes I forgot to add? Many thanks in advance Kai

3 2

Weird compilation error when using boost::geometry
by 邓尧 16 Nov '17

16 Nov '17

Hi, I have implemented my own "point" as specified by the point concept http://www.boost.org/doc/libs/1_59_0/libs/geometry/doc/html/geometry/refere… When I use it along with boost::geometry::model::polygon/multi_polygon, GCC refuses to compile, tested on GCC 4.9/5.2. What's even more weird is that CLANG 3.6 would happy accept my code. BTW, the Point implementation is part of a large project, it difficult to replace it with boost::geometry::model::point. Here is my code: Point.hpp > #ifndef RAPTOR_POINT_HPP_INCLUDED_ > > #define RAPTOR_POINT_HPP_INCLUDED_ > > >> #include <boost/mpl/int.hpp> > > #include <boost/geometry/core/access.hpp> > > #include <boost/geometry/core/cs.hpp> > > #include <boost/geometry/core/coordinate_type.hpp> > > #include <boost/geometry/core/coordinate_system.hpp> > > #include <boost/geometry/core/coordinate_dimension.hpp> > > #include <boost/geometry/geometries/polygon.hpp> > > #include <boost/geometry/multi/geometries/multi_polygon.hpp> > > >> namespace raptor { > > >> template<typename T, int tDimension = 2> > > class Point { > > public: > > Point() = default; > > >> Point(T a, T b) { > > data[0] = a; > > data[1] = b; > > } > > >> Point(T a, T b, T c) { > > data[0] = a; > > data[1] = b; > > data[2] = c; > > } > > >> T& operator [] (long index) { > > return data[index]; > > } > > >> const T& operator [] (long index) const { > > return data[index]; > > } > > >> private: > > T data[tDimension]; > > }; > > >> using CubicPoint = Point<long, 3>; > > using PlanarPoint = Point<long>; > > using SphericalPoint = Point<double>; > > >> template<typename T> > > using Polygon = boost::geometry::model::polygon<T>; > > >> template<typename T> > > using PolySet = boost::geometry::model::multi_polygon<Polygon<T>>; > > >> } // namespace raptor > > >> namespace boost { namespace geometry { namespace traits { > > >> template<typename Type, std::size_t tDimension> > > struct tag<::raptor::Point<Type, tDimension>> { > > typedef point_tag type; > > }; > > >> template<typename Type, std::size_t tDimension> > > struct coordinate_type<::raptor::Point<Type, tDimension>> { > > typedef Type type; > > }; > > >> template<typename Type, std::size_t tDimension> > > struct coordinate_system<::raptor::Point<Type, tDimension>> { > > typedef boost::geometry::cs::cartesian type; > > }; > > >> template<typename Type, std::size_t tDimension> > > struct dimension<::raptor::Point<Type, tDimension>> > > : public boost::mpl::int_<tDimension> { > > // EMPTY > > }; > > >> template<typename Type, std::size_t tDimension, std::size_t tIndex> > > struct access<::raptor::Point<Type, tDimension>, tIndex> { > > static Type get(const ::raptor::Point<Type, tDimension>& p) { > > return p[tIndex]; > > } > > >> static void set(::raptor::Point<Type, tDimension>& p, > > const Type& value) { > > p[tIndex] = value; > > } > > }; > > >> }}} // namespace boost::geometry::traits > > >> #endif // RAPTOR_POINT_HPP_INCLUDED_ > > A real simple main.cpp: > #include "Point.hpp" > > >> int main() { > > raptor::Polygon<raptor::SphericalPoint> pl; > > raptor::PolySet<raptor::SphericalPoint> set; > > return sizeof(pl) + sizeof(set); > > } > > > GCC compilation error: g++ main.cpp -std=c++14 > In file included from /usr/include/boost/geometry/core/access.hpp:20:0, from Point.hpp:5, from main.cpp:1: /usr/include/boost/geometry/core/point_type.hpp: In instantiation of > 'struct boost::geometry::traits::point_type<raptor::Point<double> >': /usr/include/boost/geometry/core/point_type.hpp:66:17: required from > 'struct boost::geometry::core_dispatch::point_type<void, > raptor::Point<double> >' /usr/include/boost/geometry/core/coordinate_type.hpp:58:62: required from > 'struct boost::geometry::core_dispatch::coordinate_type<void, > raptor::Point<double> >' /usr/include/boost/geometry/core/coordinate_type.hpp:92:25: required from > 'struct boost::geometry::coordinate_type<raptor::Point<double> >' /usr/include/boost/geometry/geometries/concepts/point_concept.hpp:90:54: > required from 'class boost::geometry::concept::Point<raptor::Point<double> > >' /usr/include/boost/concept/detail/has_constraints.hpp:32:62: required by > substitution of 'template<class Model> boost::concepts::detail::yes > boost::concepts::detail::has_constraints_(Model*, > boost::concepts::detail::wrap_constraints<Model, (& Model:: constraints)>*) > [with Model = boost::geometry::concept::Point<raptor::Point<double> >]' /usr/include/boost/concept/detail/has_constraints.hpp:42:5: required from > 'const bool > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >::value' /usr/include/boost/concept/detail/has_constraints.hpp:45:31: required > from 'struct > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >' /usr/include/boost/mpl/if.hpp:67:11: required from 'struct > boost::mpl::if_<boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >, > boost::concepts::constraint<boost::geometry::concept::Point<raptor::Point<double> > > >, boost::concepts::requirement<boost::concepts::failed************ > boost::geometry::concept::Point<raptor::Point<double> >::************> >' /usr/include/boost/concept/detail/general.hpp:50:8: required from 'struct > boost::concepts::requirement_<void > (*)(boost::geometry::concept::Point<raptor::Point<double> >)>' /usr/include/boost/geometry/geometries/ring.hpp:60:5: required from > 'class boost::geometry::model::polygon<raptor::Point<double>, true, true, > std::vector, std::vector, std::allocator, std::allocator>' main.cpp:4:42: required from here /usr/include/boost/geometry/core/point_type.hpp:45:5: error: no matching > function for call to 'assertion_failed(mpl_::failed************ > (boost::geometry::traits::point_type<raptor::Point<double> > >::NOT_IMPLEMENTED_FOR_THIS_POINT_TYPE::************)(mpl_::assert_::types<raptor::Point<double>, > mpl_::na, mpl_::na, mpl_::na>))' BOOST_MPL_ASSERT_MSG ^ /usr/include/boost/mpl/assert.hpp:82:5: note: candidate: template<bool C> > int mpl_::assertion_failed(typename mpl_::assert<C>::type) int assertion_failed( typename assert<C>::type ); ^ /usr/include/boost/mpl/assert.hpp:82:5: note: template argument > deduction/substitution failed: /usr/include/boost/geometry/core/point_type.hpp:45:5: note: cannot > convert > 'boost::geometry::traits::point_type<Geometry>::NOT_IMPLEMENTED_FOR_THIS_POINT_TYPE48::assert_arg<raptor::Point<double> > >()' (type 'mpl_::failed************ > (boost::geometry::traits::point_type<raptor::Point<double> > >::NOT_IMPLEMENTED_FOR_THIS_POINT_TYPE::************)(mpl_::assert_::types<raptor::Point<double>, > mpl_::na, mpl_::na, mpl_::na>)') to type 'mpl_::assert<false>::type {aka > mpl_::assert<false>}' BOOST_MPL_ASSERT_MSG ^ In file included from > /usr/include/boost/geometry/core/coordinate_type.hpp:21:0, from /usr/include/boost/geometry/core/access.hpp:24, from Point.hpp:5, from main.cpp:1: /usr/include/boost/geometry/core/point_type.hpp: In instantiation of > 'struct boost::geometry::core_dispatch::point_type<void, > raptor::Point<double> >': /usr/include/boost/geometry/core/coordinate_type.hpp:58:62: required from > 'struct boost::geometry::core_dispatch::coordinate_type<void, > raptor::Point<double> >' /usr/include/boost/geometry/core/coordinate_type.hpp:92:25: required from > 'struct boost::geometry::coordinate_type<raptor::Point<double> >' /usr/include/boost/geometry/geometries/concepts/point_concept.hpp:90:54: > required from 'class boost::geometry::concept::Point<raptor::Point<double> > >' /usr/include/boost/concept/detail/has_constraints.hpp:32:62: required by > substitution of 'template<class Model> boost::concepts::detail::yes > boost::concepts::detail::has_constraints_(Model*, > boost::concepts::detail::wrap_constraints<Model, (& Model:: constraints)>*) > [with Model = boost::geometry::concept::Point<raptor::Point<double> >]' /usr/include/boost/concept/detail/has_constraints.hpp:42:5: required from > 'const bool > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >::value' /usr/include/boost/concept/detail/has_constraints.hpp:45:31: required > from 'struct > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >' /usr/include/boost/mpl/if.hpp:67:11: required from 'struct > boost::mpl::if_<boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >, > boost::concepts::constraint<boost::geometry::concept::Point<raptor::Point<double> > > >, boost::concepts::requirement<boost::concepts::failed************ > boost::geometry::concept::Point<raptor::Point<double> >::************> >' /usr/include/boost/concept/detail/general.hpp:50:8: required from 'struct > boost::concepts::requirement_<void > (*)(boost::geometry::concept::Point<raptor::Point<double> >)>' /usr/include/boost/geometry/geometries/ring.hpp:60:5: required from > 'class boost::geometry::model::polygon<raptor::Point<double>, true, true, > std::vector, std::vector, std::allocator, std::allocator>' main.cpp:4:42: required from here /usr/include/boost/geometry/core/point_type.hpp:66:17: error: no type named > 'type' in 'struct boost::geometry::traits::point_type<raptor::Point<double> > >' >::type type; ^ In file included from > /usr/include/boost/geometry/geometries/polygon.hpp:26:0, from Point.hpp:10, from main.cpp:1: /usr/include/boost/geometry/geometries/concepts/point_concept.hpp: In > instantiation of 'class > boost::geometry::concept::Point<raptor::Point<double> >': /usr/include/boost/concept/detail/has_constraints.hpp:32:62: required by > substitution of 'template<class Model> boost::concepts::detail::yes > boost::concepts::detail::has_constraints_(Model*, > boost::concepts::detail::wrap_constraints<Model, (& Model:: constraints)>*) > [with Model = boost::geometry::concept::Point<raptor::Point<double> >]' /usr/include/boost/concept/detail/has_constraints.hpp:42:5: required from > 'const bool > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >::value' /usr/include/boost/concept/detail/has_constraints.hpp:45:31: required > from 'struct > boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >' /usr/include/boost/mpl/if.hpp:67:11: required from 'struct > boost::mpl::if_<boost::concepts::not_satisfied<boost::geometry::concept::Point<raptor::Point<double> > > >, > boost::concepts::constraint<boost::geometry::concept::Point<raptor::Point<double> > > >, boost::concepts::requirement<boost::concepts::failed************ > boost::geometry::concept::Point<raptor::Point<double> >::************> >' /usr/include/boost/concept/detail/general.hpp:50:8: required from 'struct > boost::concepts::requirement_<void > (*)(boost::geometry::concept::Point<raptor::Point<double> >)>' /usr/include/boost/geometry/geometries/ring.hpp:60:5: required from > 'class boost::geometry::model::polygon<raptor::Point<double>, true, true, > std::vector, std::vector, std::allocator, std::allocator>' main.cpp:4:42: required from here /usr/include/boost/geometry/geometries/concepts/point_concept.hpp:93:10: > error: 'value' is not a member of > 'boost::geometry::dimension<raptor::Point<double> >' enum { ccount = dimension<Geometry>::value }; ^ Where is the problem ? or it's a GCC bug ? Thanks

3 4

[Range, Phoenix] What am I missing...
by Robert Jones 25 Apr '17

25 Apr '17

Hi Folks Can anyone explain the output of this program... #include <iostream> #include <boost/range/algorithm/copy.hpp> #include <boost/range/counting_range.hpp> #include <boost/range/adaptor/reversed.hpp> #include <boost/range/adaptor/transformed.hpp> #include <boost/phoenix/bind/bind_function.hpp> #include <boost/phoenix/core/argument.hpp> int f( int i ) { return i * 2; } int main( ) { using boost::adaptors::reversed; using boost::adaptors::transformed; using boost::counting_range; using boost::copy; using boost::phoenix::arg_names::_1; copy( counting_range( 1, 5 ) | reversed | transformed( f ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; copy( counting_range( 1, 5 ) | reversed | transformed( bind( f, _1 ) ), std::ostream_iterator<int>( std::cout, " " ) ); std::cout << std::endl; } Which is... 8 6 4 2 1768406272 1768406272 1768406272 1768406272 I'm using Gcc 4.6.2 & Boost 1.53 Thx All.

3 4

[statechart] Passing parameters from event to State Local Storage
by Christophe Bourez 16 Nov '16

16 Nov '16

I need to maintain a parameter into the state local storage. This parameter is initially contained in the event that causes the transition to the target state. I give hereafter a small illustrative example. typename sc = boost::statechart; class EvTest : public sc::event<EvTest> { public: EvTest(std::size_t val) : value(val) {} std::size_t getValue() const { return this->value; } private: std::size_t value; }; class MyStateMachine; class StSource; class StTarget; class StSource : public sc::simple_state<StSource, MyStateMachine> { public: typedef sc::custom_reaction<EvTest> reactions; sc::result react(const EvTest &event) { // How to pass event.getValue() to the target state ? transit<StTarget>(); } }; class StTarget : public sc::simple_state<StTarget, MyStateMachine> { public: StTarget(std::size_t val) : val(value) {} private: std::size_t value; }; Thanks, Christophe

5 6

[Interprocess] Communication between x86 and x64 issue
by Toni Neubert 19 Feb '16

19 Feb '16

I want to communicate between different platforms using boost interprocess. I am using vc12 and boost 1.58 on windows 7. My code below is a very simple example, that should work. But it doesn't for communications between different platforms... If I create it in x64 and open in win32, the process stuck at a lock at function try_based_lock in boost/int/sync/detail/common_algorithms.hpp In the other way around: win32 create, x64 open: the process crashes at name_length in segment_manager_helper.hpp while trying to find the name in index (priv_generic_find in segment_manager). #include <iostream> #include <boost/interprocess/managed_shared_memory.hpp> int main() { namespace bip = boost::interprocess; // open in WIN32, create in x64 #ifdef _WIN32 bip::managed_shared_memory msm(bip::open_only, "TestIPC"); #elsif X64 bip::shared_memory_object::remove("TestIPC"); bip::managed_shared_memory msm(bip::create_only, "TestIPC", 4096); msm.construct<uint32_t>("Data")[1](10); #endif // Get Data and print it auto data = msm.find<uint32_t>("Data"); if (data.second == 1) { std::cout << *data.first << std::endl; } std::cin.ignore(); return 0; } Does anybody have experience in this? Thank you in advance!

3 2

[graph] Search algorithm using quality metric rather than distance
by rleigh＠codelibre.net 19 Feb '16

19 Feb '16

I have an adjacency_list graph (shown in attached dot file). Each edge has an attached "quality metric" as a bundled property. Similar to the dijkstra_shortest_paths algorithm, I'd like to determine the optimal path. However, this algorithm sums the distance along each edge, and finds the shortest path. What I'd like to do is *multiply* the quality metric for each edge in the path, and find the largest one. A perfect path will have a quality metric of 1.0, while suboptimal paths will have values tending towards zero, and the more "bad" edges the smaller the number. I'll likely then look at the number of edges and then select the shortest of the candidates. It seems like a simple algorithm that might already be included, but I just haven't found it yet not knowing its formal name. If anyone has any suggestions, I'd be very grateful. Many thanks, Roger

5 4

Building Boost 1.60 with VS2015 - 32 bit compiler is always selected
by Tiago Gehring 01 Feb '16

01 Feb '16

Hi, I'm trying to build Boost 1.60 with Visual Studio 2015 Update 1 in 64-bit mode but it seems to be ignoring the address-model=64 parameter and always builds a 32-bit version (I called b2 from the VS2015 Native tools for x64 command prompt): -- C:\Users\Tiago\code\boost_1_60_0>*b2 --toolset=msvc-14.0 variant=release link=static threading=multi address-model=64 architecture=x86* Performing configuration checks *- 32-bit : yes* - arm : no - mips1 : no - power : no - sparc : no - x86 : yes .... C:\Users\Tiago\code\boost_1_60_0>*cl* Microsoft (R) C/C++ Optimizing Compiler *Version 19.00.23506 for x64* Copyright (C) Microsoft Corporation. All rights reserved. usage: cl [ option... ] filename... [ /link linkoption... ] --- I saw in some ond discussion mentions to explicitly select the compiler version (I also have VS2010 and VS2012 installed) and environment variables batch file (in the project-config.jam file) but this didn't help either. Any help is really appreciated. Best regards, Tiago Gehring

4 4

Re: [Boost-users] asio: implementing sock->receive like behavior eith async_read_some
by Bjorn Reese 01 Feb '16

01 Feb '16

On 01/28/2016 01:56 PM, Lloyd wrote: > I am using asio to read some data from SSL socket. asio tcp socket > implements a "receive" function, but ssl socket doesn't have an > implementation for "receive". In the code sample given below I wish to > implement this kind of behavior. > > eg > > { > ... > sock.async_read_some(...); > //continue the execution only after the above call finishes. > } Why are you using an asynchronous operation instead of simply calling ssl::stream::read_some()?

2 1

C++Now 2016 Registration is Open
by Jon Kalb 28 Jan '16

28 Jan '16

Boost Users, Registration is now open for this year¹s C++Now (put on by Boost). http://cppnow.org/2016-conference/announcements/2016/01/28/registration-is-o pen.html The conference has sold out the last three years and is expect to do say again this year. Do not put off registering. Note that session submitters should not register until they receive instructions from Marshall Clow, our conference registrar. See you in Aspen! Jon

1 0

asio: implementing sock->receive like behavior eith async_read_some
by Lloyd 28 Jan '16

28 Jan '16

Hi, I am using asio to read some data from SSL socket. asio tcp socket implements a "receive" function, but ssl socket doesn't have an implementation for "receive". In the code sample given below I wish to implement this kind of behavior. eg { ... sock.async_read_some(...); //continue the execution only after the above call finishes. } Whats the best way to do this? I tried "future" but the code blocks/dead locks some how, The I tried "spawn", but in this case also I don't know the method to wait for the coroutine to finish. Some tips are greatly appreciated. Thanks, Lloyd

1 0

[Boost.LexicalCast] problem with 1.59 in Solaris
by dariomt＠gmail.com 28 Jan '16

28 Jan '16

Trying to compile file libs/date_time/src/gregorian/greg_month.cpp I get an error related to Boost.LexicalCast. I have reduced the problem to a minimal test case: #include <string> #include <boost/lexical_cast.hpp> void f(const char* s) { std::string s1(boost::lexical_cast<std::string>(s)); } My feeling is that this compiler has problems in the specializations for boost::detail::is_stdstring and boost::detail::is_char_array_to_stdstring. If I remove all those specializations the error goes away. I assume this is not the perfect solution because I guess this will miss some optimization of lexical_cast, but at least I can compile it this way :( Is there a better solution for this? Has this problem been fixed in 1.60? Error message (full instantiation stack available if needed): "/ThirdPartyLibs/boost/1_59_0/boost/lexical_cast/try_lexical_convert.hpp", line 146: Error: Ambiguous partial specialization for boost::detail::is_char_array_to_stdstring<std::string, const char*>, boost::detail::is_char_array_to_stdstring<boost::container::basic_string<boost::detail::CharT, boost::detail::Traits, boost::detail::Alloc>, const boost::detail::CharT*> and boost::detail::is_char_array_to_stdstring<std::basic_string<boost::detail::CharT, boost::detail::Traits, boost::detail::Alloc>, const boost::detail::CharT*>. "/ThirdPartyLibs/boost/1_59_0/boost/lexical_cast.hpp", line 42: Where: While instantiating "boost::conversion::detail::try_lexical_convert<std::string, const char*>(const char*const&, std::string &)". "/ThirdPartyLibs/boost/1_59_0/boost/lexical_cast/try_lexical_convert.hpp", line 134: Error: Ambiguous partial specialization for boost::detail::is_stdstring<std::string>, boost::detail::is_stdstring<boost::container::basic_string<boost::detail::CharT, boost::detail::Traits, boost::detail::Alloc>> and boost::detail::is_stdstring<std::basic_string<boost::detail::CharT, boost::detail::Traits, boost::detail::Alloc>>. "/ThirdPartyLibs/boost/1_59_0/boost/lexical_cast.hpp", line 42: Where: While instantiating "boost::conversion::detail::try_lexical_convert<std::string, const char*>(const char*const&, std::string &)".

5 9

Regression with boost::python 1.60
by Emmanuel 28 Jan '16

28 Jan '16

Hello, I am not sure if this is the right place to do it, but I will try :-). I am having a regression in boost 1.60, I documented a small reproducer here: http://stackoverflow.com/questions/35056398/typeerror-when-iterating-over-a… Does anyone have a clue ? Cheers, Emmanuel

1 0

[Odeint] Stiff System of differential equations
by jules 25 Jan '16

25 Jan '16

Hi all, I am currently working with a very large set of differential equations; it is a disease model with 20160 classes depending on which vaccine has been admnistered, history of infection, and age. To solve this I have been using the runge_kutta_fehlber78 controlled stepper with the integrate_const function. There I need to set the absolute_error, relative_error and the step_size. My issue is that the results from the solver seems to depend highly on the step_size and whether or not an observer is provided. Since the solver is adaptive I feel like the results should not depend on step_size and they should definitely not depend on the presence of an observer. My question is why would the results be related to the step_size or the observer? How would it be possible to get the same results regardless of the step_size and the presence of an observer? Could this be related to the system being stiff and if so how would it be possible to solve it (The jacobian is too complicated to calculate because of the population dynamics)? Any help would be appreciated. Many thanks, Jules

3 5

BGL, shortest path between two nearby nodes in a huge graph
by Paolo Bolzoni 25 Jan '16

25 Jan '16

Dear list, I am a happy user of BGL, but recently I got stuck in a strange problem. I think I am missing the obvious, so I'll be happy to read the fine manual if it's the case. Just point me to the right direction. I need to find the shortest path between two nodes, for doing so I am using dijkstra with a custom visitor that stops the search (throwing an exception) when examine_vertex is called on the destination node. It worked fine, but it run strangely slow. After some profiling, it is clear that most of the time is used in the initialize_vertex function. The graph is fairly large, but the path I am looking for are fairly small (10 edges tops usually). It is possible to skip the initialize phase? Cheers, Paolo

3 5

Some help for betweenness centrality for undirected weighted graph
by Xinran Wang 25 Jan '16

25 Jan '16

Hi everyone, this is from Jason. I am a new user of Boost library. Nowadays, I am doing a research about betweenness centrality measure. I am very confused about how to use boost to calculate the betweenness centrality. I need to calculate the centrality score based on a undirected and weighted graph. The following code is what I tried to do. But this block of code can only be used for calculated for unweighted graph. Could anyone here can offer me examples? Thanks for any reply. #include <boost/graph/betweenness_centrality.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/graphviz.hpp> typedef boost::property<boost::edge_weight_t, float> EdgeWeightProperty; typedef boost::adjacency_list < boost::listS, boost::vecS, boost::undirectedS, boost::no_property, EdgeWeightProperty > Graph; typedef boost::graph_traits < Graph >::vertex_descriptor vertex_descriptor; typedef boost::graph_traits < Graph >::edge_descriptor edge_descriptor; typedef std::pair<int, int> Edge; typedef std::map<Edge, int> StdEdgeIndexMap; void betweennessCentrality() { Graph g; Graph::vertex_descriptor a1 = boost::add_vertex(g); Graph::vertex_descriptor a2 = boost::add_vertex(g); Graph::vertex_descriptor a3 = boost::add_vertex(g); Graph::vertex_descriptor a4 = boost::add_vertex(g); Graph::vertex_descriptor a5 = boost::add_vertex(g); Graph::vertex_descriptor a6 = boost::add_vertex(g); Graph::vertex_descriptor a7 = boost::add_vertex(g); EdgeWeightProperty weight0 = 1; boost::add_edge(a1, a2, weight0, g); EdgeWeightProperty weight1 = 1; boost::add_edge(a1, a3, weight1, g); EdgeWeightProperty weight2 = 1; boost::add_edge(a2, a3, weight2, g); EdgeWeightProperty weight3 = 1; boost::add_edge(a3, a4, weight3, g); EdgeWeightProperty weight4 = 1; boost::add_edge(a4, a5, weight4, g); EdgeWeightProperty weight5 = 1; boost::add_edge(a5, a6, weight5, g); EdgeWeightProperty weight6 = 1; boost::add_edge(a5, a7, weight6, g); EdgeWeightProperty weight7 = 1; boost::add_edge(a6, a7, weight7, g); typedef boost::property_map< Graph, boost::vertex_index_t>::type VertexIndexMap; VertexIndexMap v_index = get(boost::vertex_index, g); std::vector< double > v_centrality_vec(boost::num_vertices(g), 0.0); boost::iterator_property_map< std::vector< double >::iterator, VertexIndexMap > v_centrality_map(v_centrality_vec.begin(), v_index); brandes_betweenness_centrality( g, v_centrality_map); }

1 0

[math/stat] generating t-distributed random numbers
by U.Mutlu 22 Jan '16

22 Jan '16

Hi, I've an old code that creates a normal-distributed random number between 0 and 1 (by using the polar method). Is it possible to convert this number to a t-distributed number (with v=5) using boost? Or, alternatively: how to generate t-distributed random numbers in the range 0 to 1 with v=5 (ie. degrees of freedom = 5) in boost?

1 1

[fusion] [mpl] binary MPL transform on empty fusion vectors
by Nathan Ridge 22 Jan '16

22 Jan '16

Hi, I've run into an error in code involving MPL and Fusion which I've reduced to the following: #include <boost/mpl/transform.hpp> #include <boost/fusion/container/vector.hpp> #include <boost/fusion/mpl.hpp> struct predicate { template <typename T, typename U> struct apply { typedef T type; }; }; typedef boost::mpl::transform< boost::fusion::vector<>, boost::fusion::vector<>, predicate> ::type Result; This simple piece of code tries to perform a binary MPL transform on two fusion vectors of size 0. It produces the error reproduced below, with both gcc 5.1 and clang 3.7. My boost version is 1.60. I'm quite sure that this used to work with an older boost and compiler version combination, though I don't recall which exactly (something in the vicinity of boost 1.54 / gcc 4.8). Did I run into a regression, or should I not be expecting this to work in the first place? Should I be special-casing zero-length vectors? Thanks, Nate In file included from test.cpp:2: In file included from boost/include/boost/fusion/container/vector.hpp:12: In file included from boost/include/boost/fusion/container/vector/vector.hpp:28: In file included from boost/include/boost/fusion/container/vector/detail/at_impl.hpp:12: boost/include/boost/fusion/container/vector/detail/value_at_impl.hpp:50:57: error: no matching function for call to 'value_at_impl' typedef typename mpl::identity<decltype(seq::template value_at_impl<N::value>(boost::declval<seq*>()))>::type::type type; ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ boost/include/boost/fusion/container/vector/detail/value_of_impl.hpp:30:61: note: in instantiation of template class 'boost::fusion::extension::value_at_impl<boost::fusion::vector_tag>::apply<boost::fusion::vector<>, mpl_::int_<0>>' requested here typedef typename value_at_impl<vector_tag>::template apply<vector, index>::type type; ^ boost/include/boost/fusion/iterator/value_of.hpp:52:15: note: in instantiation of template class 'boost::fusion::extension::value_of_impl<boost::fusion::vector_iterator_tag>::apply<boost::fusion::vector_iterator<boost::fusion::vector<>, 0>>' requested here : extension::value_of_impl<typename detail::tag_of<Iterator>::type>:: ^ boost/include/boost/fusion/iterator/mpl/fusion_iterator.hpp:47:45: note: in instantiation of template class 'boost::fusion::result_of::value_of<boost::fusion::vector_iterator<boost::fusion::vector<>, 0>>' requested here typedef typename fusion::result_of::value_of<Iterator>::type type; ^ boost/include/boost/mpl/iterator_category.hpp:27:22: note: in instantiation of template class 'boost::mpl::fusion_iterator<boost::fusion::vector_iterator<boost::fusion::vector<>, 0>>' requested here typedef typename Iterator::category type; ^ boost/include/boost/mpl/pair_view.hpp:152:20: note: in instantiation of template class 'boost::mpl::iterator_category<boost::mpl::fusion_iterator<boost::fusion::vector_iterator<boost::fusion::vector<>, 0>>>' requested here typename iterator_category<iter1_>::type ^ boost/include/boost/mpl/aux_/has_tag.hpp:20:1: note: in instantiation of template class 'boost::mpl::pair_view<boost::fusion::vector<>, boost::fusion::vector<>>' requested here BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_tag, tag, false) ^ boost/include/boost/mpl/has_xxx.hpp:245:65: note: expanded from macro 'BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF' , boost::mpl::aux::type_wrapper<BOOST_MSVC_TYPENAME U::name>* = 0 \ ^ boost/include/boost/mpl/aux_/has_tag.hpp:20:1: note: while substituting deduced template arguments into function template 'test' [with U = boost::mpl::pair_view<boost::fusion::vector<>, boost::fusion::vector<>>] BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF(has_tag, tag, false) ^ boost/include/boost/mpl/has_xxx.hpp:253:18: note: expanded from macro 'BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF' sizeof(gcc_3_2_wknd::test(static_cast<t_*>(0))) \ ^ boost/include/boost/config/suffix.hpp:394:72: note: expanded from macro 'BOOST_STATIC_CONSTANT' # define BOOST_STATIC_CONSTANT(type, assignment) static const type assignment ^ boost/include/boost/mpl/sequence_tag.hpp:112:30: note: in instantiation of template class 'boost::mpl::aux::has_tag<boost::mpl::pair_view<boost::fusion::vector<>, boost::fusion::vector<>>, mpl_::bool_<false>>' requested here ::boost::mpl::aux::has_tag<Sequence>::value ^ boost/include/boost/mpl/O1_size.hpp:30:30: note: in instantiation of template class 'boost::mpl::sequence_tag<boost::mpl::pair_view<boost::fusion::vector<>, boost::fusion::vector<>>>' requested here : O1_size_impl< typename sequence_tag<Sequence>::type> ^ boost/include/boost/mpl/fold.hpp:34:25: note: in instantiation of template class 'boost::mpl::O1_size<boost::mpl::pair_view<boost::fusion::vector<>, boost::fusion::vector<>>>' requested here ::boost::mpl::O1_size<Sequence>::value ^ boost/include/boost/mpl/transform.hpp:75:7: note: in instantiation of template class 'boost::mpl::fold<boost::mpl::pair_view<boost::fusion::vector<>, boost::fusion::vector<>>, boost::fusion::vector<>, boost::mpl::bind2<boost::mpl::push_back<mpl_::na, mpl_::na>, mpl_::arg<1>, boost::mpl::bind2<predicate, boost::mpl::bind1<boost::mpl::first<mpl_::na>, mpl_::arg<2>>, boost::mpl::bind1<boost::mpl::second<mpl_::na>, mpl_::arg<2>>>>>' requested here : fold< ^ boost/include/boost/mpl/transform.hpp:114:1: note: in instantiation of template class 'boost::mpl::aux::transform2_impl<boost::fusion::vector<>, boost::fusion::vector<>, predicate, boost::mpl::back_inserter<boost::fusion::vector<>>>' requested here BOOST_MPL_AUX_INSERTER_ALGORITHM_DEF(4, transform2) ^ boost/include/boost/mpl/aux_/inserter_algorithm.hpp:52:7: note: expanded from macro 'BOOST_MPL_AUX_INSERTER_ALGORITHM_DEF' : if_< has_push_back< typename clear<P1>::type> \ ^ boost/include/boost/mpl/eval_if.hpp:38:22: note: in instantiation of template class 'boost::mpl::transform2<boost::fusion::vector<>, boost::fusion::vector<>, predicate, mpl_::na>' requested here typedef typename f_::type type; ^ boost/include/boost/mpl/transform.hpp:138:1: note: in instantiation of template class 'boost::mpl::eval_if<boost::mpl::or_<boost::mpl::is_na<predicate>, boost::mpl::is_lambda_expression<boost::fusion::vector<>>, boost::mpl::not_<boost::mpl::is_sequence<boost::fusion::vector<>>>, mpl_::bool_<false>, mpl_::bool_<false>>, boost::mpl::transform1<boost::fusion::vector<>, boost::fusion::vector<>, predicate>, boost::mpl::transform2<boost::fusion::vector<>, boost::fusion::vector<>, predicate, mpl_::na>>' requested here AUX778076_TRANSFORM_DEF(transform) ^ boost/include/boost/mpl/transform.hpp:125:22: note: expanded from macro 'AUX778076_TRANSFORM_DEF' typedef typename eval_if< \ ^ test.cpp:13:17: note: in instantiation of template class 'boost::mpl::transform<boost::fusion::vector<>, boost::fusion::vector<>, predicate, mpl_::na>' requested here boost::mpl::transform< ^ boost/include/boost/fusion/container/vector/vector.hpp:275:30: note: candidate template ignored: could not match 'store' against 'vector' mpl::identity<U> value_at_impl(store<N, U>*); ^

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Boost Log: Use of operator<<
by Florian Lindner 21 Jan '16

21 Jan '16

Hello, I want to put a custom object called DynamicVector on the BOOG_LOG_SEV stream. For that I defined an operator<< template<typename Vector> typename std::enable_if<tarch::la::IsVector<Vector>::value, std::ostream&>::Type operator<< (std::ostream & os, const Vector & vector); IsVector<Vector> will be true, since template<typename Scalar> struct IsVector<DynamicVector<Scalar> > { static const int value = true; }; The operator itself is working: // getCoords returns a DynamicVector<double> std::cout << inMesh->vertices()[j].getCoords(); // compiles just fine. but BOOST_LOG_SEV(_log, boost::log::trivial::severity_level::error) << inMesh->vertices()[j].getCoords(); gives an compile error: /usr/include/boost/log/utility/formatting_ostream.hpp:799:19: error: invalid operands to binary expression ('ostream_type' (aka 'basic_ostream<char_type, traits_type>') and 'const tarch::la::DynamicVector<double>') strm.stream() << value; str.stream() seems to be an ostream_type which is an basic_ostream<char_type, traits_type>. I wonder why this isn't convertible to std::ostream, like http://stackoverflow.com/questions/17269499/overloading-operator-for-boost-… and the comment at http://www.boost.org/doc/libs/1_54_0/boost/log/utility/formatting_ostream.h… suggest. Any help appreciated! Thanks, Florian

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Re: [Boost-users] [boost] Boost.Operators issue: polluting namespace of caller through argument-dependent lookup
by John M. Dlugosz 21 Jan '16

21 Jan '16

On 1/20/2016 10:41 AM, Daniel Frey wrote: > In a way it makes library collections like Boost harder and I still think you should use > qualified lookup in your specific case, No, I specifically don't want to qualify every use, as explained originally. The code needs compatibility with some configurations that require the tr1 namespace and others that prohibit it. Qualifying every reference is bad; rather, import them in one place. You are basically saying that `using N::foo;` is never right because someone may happen to use the name foo in an unrelated library and ADL is a misfeature? I think that doesn't scale. It should be SOP to isolate classes that are meant to be used as base classes by library consumers, and treat unqualified lookup of names pulled in to the local scope via `using` as something that is a useful feature that ought to work. > but as I already said in another mail I’m willing to fix it. I just need to figure out > where to commit and merge stuff as the last time I worked on it we were still using svn > and the branching model was different. I hope to be able to find the time somewhere in > the next days. Regards, Daniel Looking forward to it in 1.62 or whatever. Thanks! —John

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[locale] boost::locale::format number formatting on OS X and Windows
by Michael Smith 21 Jan '16

21 Jan '16

Using Boost.Locale from Boost 1.60.0 (installed via homebrew, so it uses icu) on Mac OS X 10.11.2, I seem to be getting unexpected behavior for some of the boost::format number formatting. A short example program #include <boost/locale.hpp> int main(int argc, char** argv) { boost::locale::format fmt("{1,number} should be 1,25."); fmt % 1.25; boost::locale::generator gen; std::cout << fmt.str(gen("fr-fr.UTF-8")) << std::endl; return 0; } That produces 1,25 on Linux, and 1.25 on Windows (using mingw-w64) and Mac. Any idea why they'd represent it differently?

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Re: [Boost-users] Using Coroutines in the Visitor Pattern (use-case: BGL event visitor)
by alex 20 Jan '16

20 Jan '16

>-----Original Message----- >From: Boost-users [mailto:boost-users-bounces@lists.boost.org] On Behalf Of >Daniel Hofmann >Sent: 17 November 2015 15:55 >To: boost-users(a)lists.boost.org >Subject: [Boost-users] Using Coroutines in the Visitor Pattern (use-case: BGL >event visitor) > >(Disclaimer: this is not only specific to BGL, I can think of similar >use-cases where the visitor pattern is used --- I will still explain it >in the BGL context, as it is probably easier to understand) > > >Suppose you have a BGL graph and want to implement s-t shortest path >queries. It is possible to do this by using a bi-directional approach, >that is starting a Dijkstra search [1] from the start and starting a >additional Dijkstra search from the target. As soon as they "meet in the >middle", you can unpack the two sub-paths. > >[snip] > >It then came to my mind that I could use Coroutines for cooperative >multitasking, without the downsides that come with threading. > >My idea was to invert the callbacks using Coroutines as it is shown in >the SAX parsing example [3], in order to get a lazy range of vertices >each visitor examines. I then could simply walk the two ranges, >terminating as soon as there is the same element in both. Jeremiah Willcock gave a good description of how this could work: http://lists.boost.org/Archives/boost/2012/07/195300.php The way he describes it is really using coroutines instead of the visitor pattern. > > >But due to way the dijkstra_shortest_path function adds an additional >level of indirection I failed to implement this, and I have strong >doubts that it is possible with Coroutines at all. I> >I'm mainly struggling with wrapping my head around stopping and resuming >the dijkstra_shortest_path function, when all I can modify is the >visitor it takes. That is, the reason I can not make it work is that I >can not launch two dijkstra_shortest_path functions asynchronously with >just Coroutines. > I think there are two options: 1. Let your visitor throw an exception to get out of the dijkstra shortest path function; use some version of the function that skips initialization to resume again (the existing dijkstra_shortest_path_no_init is not good enough, so you would have to make one). 2. Reimplement the dijkstra function as a coroutine. I have implemented both, but have only really used option 1; whereas option 2 remained a toy experiment. In both cases the tricky part was to properly initialize and keep track of(and not re-initialize on resume) all parameters that are input to the dijkstra function, i.e. color_map, queue, distance_map, etc. https://github.com/ahhz/resumable_dijkstra I used the lightweight stackless coroutine of Boost ASIO. http://www.boost.org/doc/libs/1_59_0/doc/html/boost_asio/reference/coroutine .html >The control flow I need would probably look like this: start the first >Dijkstra search, on its first vertex it visits, "jump back out" and >start the second Dijkstra visitor. From there on ping-pong between the >two visitors exclusively. And I'm not sure this is possible with the >Coroutine approach. > It depends how much you are willing to re-implement. It is possible in principle >I appreciate any tips in this regard, even if it's a "just use your 15 >lines of threading code instead of trying to be fancy" :) > I think it would be great to have a fancy solution for this in BGL.

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boost serialization
by Виктория Доможакова 20 Jan '16

20 Jan '16

I use boost serialization in my project. I I conducted f an experiment: 1) I removed one line with the data in the boost archive file. 2) I started my project. 3) All variables initialized in the constructor. 4) Value of variables loaded from boost archive in order . 5) When queue comes to removing values , I get exeption (I handle exeption with try-catch ) and file didn't read to end and close. 6) But this variable is equal to the value next after removal . My question: why this variable is equal to the value next after removal . if this variable has value from constructor than it is more logic. -- Виктория Доможакова

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[gsoc16] Attn: We need 2016 mentors and project ideas for Boost!
by Niall Douglas 20 Jan '16

20 Jan '16

Dear Boost community, We are now within one month of the beginning of Google Summer of Code 2016! Last year's GSoC was a particularly momentus one as we witnessed the approval by the community for Boost.Hana to enter Boost - congratulations to Louis and his mentor Joel for bringing to Boost a very exciting new C++ library which pushes C++ compilers to their limits. We have also seen greatly improved retention of GSoC students in the community thanks to the improved student selection procedures introduced last year, and the fresh blood brought into Boost has been very evident on the mailing list this year. As part of filling in our application for 2016, we must supply to Google a list of potential GSoC mentors and potential GSoC projects for summer 2016 in order to be approved as an organisation this year. Therefore a lengthy page of awesome project ideas at https://svn.boost.org/trac/boost/wiki/SoC2016 before *February 8th* would be an enormous help to getting us approved again this year and bringing to Boost another US$35,000 of Google funding. If you think yourself able to mentor a student doing some work on Boost this summer, *please* consider adding a description of the proposed work item and your name to the list. Last year we had more slots awarded to us by Google than we had good combinations of student and mentor, so we had to return slots which I believe has not happened here at Boost GSoC in at least a decade. That means that your project ideas have a better chance than ever of receiving funding if you can find a good student, and that is best done by getting project ideas floated *early*. If you want to know more about mentoring a Google Summer of Code funded student work before you nominate yourself, please feel free to ask on the main Boost developers mailing list boost(a)lists.boost.org or via gsoc-admin(a)boost.org. Thank you in advance for your time. --- Boost C++ Libraries Google Summer of Code 2016 admin https://svn.boost.org/trac/boost/wiki/SoC2016

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Using Coroutines in the Visitor Pattern (use-case: BGL event visitor)
by Daniel Hofmann 19 Jan '16

19 Jan '16

(Disclaimer: this is not only specific to BGL, I can think of similar use-cases where the visitor pattern is used --- I will still explain it in the BGL context, as it is probably easier to understand) Suppose you have a BGL graph and want to implement s-t shortest path queries. It is possible to do this by using a bi-directional approach, that is starting a Dijkstra search [1] from the start and starting a additional Dijkstra search from the target. As soon as they "meet in the middle", you can unpack the two sub-paths. In terms of the BGL this would roughly look like the following (simplified, with synchronization and visitor omitted): Vertex middle; async(dijkstra_shortest_paths(g, start, visitor(v{middle}))); async(dijkstra_shortest_paths(g, target, visitor(v{middle}))); where the visitors single-step all vertices in their examine_vertex callback [2] and check if they met in the middle. While this is quite easy to implement with threading, is has its downsides, mainly in synchronization for this ping-pong play between the two visitors, resulting in contention on the synchronization locks. But also the overhead of using threads might be too high for smaller graphs. It then came to my mind that I could use Coroutines for cooperative multitasking, without the downsides that come with threading. My idea was to invert the callbacks using Coroutines as it is shown in the SAX parsing example [3], in order to get a lazy range of vertices each visitor examines. I then could simply walk the two ranges, terminating as soon as there is the same element in both. But due to way the dijkstra_shortest_path function adds an additional level of indirection I failed to implement this, and I have strong doubts that it is possible with Coroutines at all. I'm mainly struggling with wrapping my head around stopping and resuming the dijkstra_shortest_path function, when all I can modify is the visitor it takes. That is, the reason I can not make it work is that I can not launch two dijkstra_shortest_path functions asynchronously with just Coroutines. The control flow I need would probably look like this: start the first Dijkstra search, on its first vertex it visits, "jump back out" and start the second Dijkstra visitor. From there on ping-pong between the two visitors exclusively. And I'm not sure this is possible with the Coroutine approach. I appreciate any tips in this regard, even if it's a "just use your 15 lines of threading code instead of trying to be fancy" :) Cheers, Daniel J H [1] http://www.boost.org/doc/libs/1_59_0/libs/graph/doc/dijkstra_shortest_paths… [2] http://www.boost.org/doc/libs/1_59_0/libs/graph/doc/DijkstraVisitor.html [3] http://www.boost.org/doc/libs/1_59_0/libs/coroutine/doc/html/coroutine/moti…

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Re: [Boost-users] boost.dll winapi compile error
by Elod G 18 Jan '16

18 Jan '16

I was missing the latest winapi module, duh. ElodG On 1/18/2016 19:00, boost-users-request(a)lists.boost.org wrote: > Message: 1 > Date: Sun, 17 Jan 2016 23:12:32 +0200 > From: Elod G <gyelod(a)gmail.com> > To: boost-users(a)lists.boost.org > Subject: [Boost-users] boost.dll winapi compile error > Message-ID: <569C03BF.9030305(a)gmail.com> > Content-Type: text/plain; charset=utf-8 > > Hello All, > > I cloned origin/master of https://github.com/boostorg/dll and copied > include/ to the 1.60 release of boost to give boost.DLL a go. > > I am getting the following compile error when including: "boost/dll.hpp" > boost\dll\detail\windows\shared_library_impl.hpp:140: error: C2039: > 'get_proc_address' : is not a member of 'boost::detail::winapi' > > I am using VS2013. > > What am I missing? > > -- > ElodG

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