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Windows installation issues
by Alexander Carôt 01 Aug '16

01 Aug '16

Hi all, after having switched from OSX and Linux to Windows 10 I have issues compiling boost (1.61)with the MinGW compiler. The very first step fails: bootstrap.bat mingw results in not finding a right path, denying access and aborting the installation. So far I only found this article: https://andres.jaimes.net/698/use-c-with-mingw-and-netbeans-in-windows/ but it does not contain further info how (and where) to add additional info (I added c:\MinGW\bin to my PATH but it didn’t help). Any help appreciated, thanks in advance Alex --

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Python TypeError with application compiled with CXX11_ABI=0
by Jackson Wiegman 29 Jul '16

29 Jul '16

Hi, I have an application I am trying to compile on Ubuntu 16.04. This is using GCC 5.4.0 and libboost 1.58.0 (stock libraries). The application has a linking to a library that was built with GCC 4.*, so I have to compile with D_GLIBCXX_USE_CXX11_ABI=0 to get backwards comparability (otherwise I have undefined abi:cxx11 links). However when I do this, I get a TypeError in Python: TypeError: No registered converter was able to produce a C++ rvalue of type > std::string from this Python object of type str It looks like boost is having a problem working without the ABI. Does anyone have a work-around or a patch for this? Jackson

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[Python] gcc error compiling boost
by Àlex Jarauta 29 Jul '16

29 Jul '16

Dear all, my name is Alex and I am a postdoc at the University of Alberta, Edmonton, Canada. I am working with an in-house opensource code that uses boost to wrap C++ code with Python. In the latest version of our code, one has to download boost manually and compile it. I have tried wot two different versions (1.59 and 1.60) and I can compile them with python 2.7. However, if I try to compile it using either Python 3.3 or 3.5, I always get the same error: "./boost/python/detail/wrap_python.hpp:50:23: fatal error: pyconfig.h: No such file or directory # include <pyconfig.h>" I have been looking for this error for a while, but I have not been able to find a proper solution. I wonder if you could help me on this matter. Thank you very much for your attention. Best regards, Àlex

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Graph: Trying to filter on custom properties
by Amit Prakash Ambasta 29 Jul '16

29 Jul '16

How should I be writing the get_filtered_graph in a generic way? #include <map> #include <string> #include <vector> #include <iostream> #include <boost/graph/adjacency_list.hpp> #include <boost/property_map/property_map.hpp> #include <boost/graph/filtered_graph.hpp> #include <boost/graph/graph_utility.hpp> template <typename F> struct EdgeProperty { F features; EdgeProperty() = default; EdgeProperty(const F& f) : features(f) {} }; template <typename EM, typename F> struct filtered_edge { F filters; EM emap; filtered_edge() = default; filtered_edge(EM emap_, F filters_) : emap(emap_), filters(filters_) {} template <typename E> bool operator()(const E& e) { auto e_prop = get(emap, e); auto e_feat = e_prop.features; for (auto it: e_feat) { if (get(e_feat, it.first) != it.second) { return false; } } return true; } }; template<typename G, typename F> G get_filtered_graph(G& g, F& filters) { typedef filtered_edge<boost::property_map<G, EdgeProperty<F> >, F> filter_fn; filter_fn filter{get(&EdgeProperty<F>::features, g), filters}; boost::filtered_graph<G, filter_fn> fg(g, filter); return fg; } typedef std::map<std::string, int> dict; typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::directedS, boost::no_property, EdgeProperty<dict> > Graph; Graph create_empty_graph() noexcept { return {}; } int main() { const char* name = "ABCDE"; auto g = create_empty_graph(); auto v0 = boost::add_vertex(g); auto v1 = boost::add_vertex(g); auto v2 = boost::add_vertex(g); dict d01; d01["a"] = 1; dict d12; d12["b"] = 1; dict fil; fil["a"] = 1; auto ep01 = EdgeProperty<dict>{ dict{} }; boost::add_edge(v0, v1, d01, g); boost::add_edge(v1, v2, d12, g); std::cout << "Before filter" << std::endl; boost::print_graph(g, name); auto fg = get_filtered_graph(g, fil); std::cout << "After filter" << std::endl; boost::print_graph(fg, name); Graph ga; }

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[boost.geometry] concept namespace conflicts with new concept keyword (gcc 6.1)
by kique G 28 Jul '16

28 Jul '16

Hello, I am using boost.geometry with gcc 6.1 and I am finding conflicts between the new concept keyword (-fconcepts) and the concept namespace: /usr/include/boost/geometry/geometries/concepts/point_concept.hpp:33:50: error: expected identifier before 'concept' Am I missing something? If not, are there any plans for renaming this namespace? Do you know of any other incompatibilities between the boost libraries and the concepts TS? Thanks and best regards, Enrique Garcia

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SVGMath no longer available
by Je suis la poubelle 27 Jul '16

27 Jul '16

Hi, I don't have any question to ask (yet :) ) but have a comment. In the folder "libs\math\doc\html\math_toolkit", there's the file sf_implementation.html. Inside this file, there's a section called "Creating and Managing the Equations". Inside it, you talked about a program called SVGMath (with a hyperlink). However, the hyperlink points to a website which no longer exists. Have a nice day

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[boost.geometry] Why point coordinates are stored to SVG as integers?
by Mikhail Matrosov 27 Jul '16

27 Jul '16

Hello, I'm using boost::geometry::svg_mapper to save my shapes with floating point coordinates into an .svg file. It works great, but they are stored as integers. I can see this line in svg_mapper.hpp: namespace detail { namespace svg { typedef model::point<int, 2, cs::cartesian> svg_point_type; }} Thus svg_point is clearly defined to have integer coordinates. However, it is not convenient - SVG handles floating point coordinated perfectly well. Why not using original type of the serialized collection and let streams handle representation? ----- Best regards, Mikhail Matrosov

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Re: [Boost-users] lockfree : getting a move only type into spsc_queue
by Bjorn Reese 24 Jul '16

24 Jul '16

On 07/23/2016 11:36 PM, Thomas Novotny wrote: > In the end Imade a custom version of spsc_queue. Getting this working > (as a hack) was fairly easy, so I wanted to share it in the hope that a > better solution might make it into a future version of the library. FYI, there is a pull request about adding move support to spsc_queue, but the consequences have not been fully examined yet: https://github.com/boostorg/lockfree/pull/24 In the meanwhile, you can make a cleaner solution with a unique_ptr specialization of spsc_queue. See attachment. > bool push( T & t, T * buffer, size_t max_size ) T&& t

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lockfree : getting a move only type into spsc_queue
by Thomas Novotny 23 Jul '16

23 Jul '16

I had a unique_ptr from a pool with a custom deleter that I needed to get int a lockfree queue. This did not work out of the box with either boost::lockfree::queue or boost::lockfree::spsc_queue. There were three main issues: * default construction * copying * copy construction To solve the issue with default constructability I had to wrap the unique_ptr in a class. In the end Imade a custom version of spsc_queue. Getting this working (as a hack) was fairly easy, so I wanted to share it in the hope that a better solution might make it into a future version of the library. In essence, I only had to add some std::move calls and adjust the api for push. two lines here: bool push(T const & t, T * buffer, size_t max_size) { const size_t write_index = write_index_.load(memory_order_relaxed); // only written from push thread const size_t next = next_index(write_index, max_size); if (next == read_index_.load(memory_order_acquire)) return false; /* ringbuffer is full */ new (buffer + write_index) T(t); // copy-construct write_index_.store(next, memory_order_release); return true; } to bool push( T & t, T * buffer, size_t max_size ) { const size_t write_index = write_index_.load( memory_order_relaxed ); // only written from push thread const size_t next = next_index( write_index, max_size ); if( next == read_index_.load( memory_order_acquire ) ) return false; /* ringbuffer is full */ new (buffer + write_index) T(); // default-construct *(buffer + write_index) = std::move( t ); // move write_index_.store( next, memory_order_release ); return true; } a line here: bool push(T const & t) { return base_type::push(t); } to bool push(T & t) { return base_type::push(t); } and a few lines here template< class OutputIterator > OutputIterator copy_and_delete( T * first, T * last, OutputIterator out ) { if (boost::has_trivial_destructor<T>::value) { return std::copy(first, last, out); // will use memcpy if possible } else { for (; first != last; ++first, ++out) { *out = *first; first->~T(); } return out; } } to template< class OutputIterator > OutputIterator copy_and_delete( T * first, T * last, OutputIterator out ) { for (; first != last; ++first, ++out) { *out = std::move(*first); first->~T(); } return out; } In copy_payload there is only one change struct copy_convertible { template <typename T, typename U> static void copy(T & t, U & u) { u = t; } }; became template <typename T, typename U> static void copy(T & t, U & u) { u = std::move(t); } and that was it. The result is not pretty but works (only single element push and pop used).

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Boost Social Event at CppCon 2016
by Jon Kalb 23 Jul '16

23 Jul '16

Boost Users, Because a lot of Boosters are going to be attending CppCon, we¹d like to arrange a social event for Boosters/C++Now attendees. http://cppcon.org/ If you are planning to attend CppCon or even If you are just going to be in or around Bellevue, Washington between September 17th and 23rd and you¹d like to join us for dinner, please let us know so we can get a count. Please send mail to: social(a)boost.org Once we settle on a date, etc, we¹ll let everyone who responded know when and where, so please let us know, even if you are a ³maybe.² If you are attending, please make your hotel reservations soon. We are likely to sell out of our room block. http://cppcon.org/lodging/ I hope to see you at CppCon. Jon

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