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Filesystem recursive iterator issues
by mlimber 24 Oct '16

24 Oct '16

I have this code, which does a simple recursive directory iteration and prints each directory entry and then does it again ( http://coliru.stacked-crooked.com/a/0bfab95a513ebed8 ): #include <boost/filesystem.hpp> #include <boost/range/iterator_range.hpp> #include <iostream> namespace fs = boost::filesystem; int main() { try { const auto iter = fs::recursive_directory_iterator{ "." }; for( const auto& entry : boost::make_iterator_range( iter, {} ) ) { std::cout << entry << "\n"; } // Rinse and repeat std::cout << "\n"; for( const auto& entry : boost::make_iterator_range( iter, {} ) ) // CRASH -- Replace 'iter' with 'fs::recursive_directory_iterator{"."}' and it will work. //for( const auto& entry : boost::make_iterator_range( fs::recursive_directory_iterator{"."}, {} ) ) { std::cout << entry << "\n"; } } catch( const std::exception& e ) { std::cerr << e.what() << "\n"; } catch( ... ) { std::cerr << "Unknown exception.\n"; } } As you can see at Coliru, it crashes. (It also crashes on Visual Studio 2012 and with Boost 1.55.0 and on Coliru with <experimental/filesystem> instead of Boost.) Similarly, using a filesystem iterator with std::distance() fails when the iterator passed in is used again later (with boost: http://coliru.stacked-crooked.com/a/1b06dca057872762 and with experimental/filesystem: http://coliru.stacked-crooked.com/a/7bd5e73f1444619d ). It seems that something in the state of the *constant* iterator gets confused or corrupted after it is advanced to the end. I have a workaround for it commented out in the code. I found this possibly related issue: https://svn.boost.org/trac/boost/ticket/11910 Am I missing something? Should I file a new bug report? Cheers! M

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When to use BOOST_ALL_DYN_LINK?
by Florian Lindner 24 Oct '16

24 Oct '16

Hello, http://www.boost.org/doc/libs/1_62_0/libs/log/doc/html/log/installation/con… says: BOOST_LOG_DYN_LINK If defined in user code, the library will assume the binary is built as a dynamically loaded library ("dll" or "so"). Otherwise it is assumed that the library is built in static mode. This macro must be either defined or not defined for all translation units of user application that uses logging. This macro can help with auto-linking on platforms that support it. BOOST_ALL_DYN_LINK Same as BOOST_LOG_DYN_LINK but also affects other Boost libraries the same way. We build our library in a dynamic and a static version using SCons: staticlib = env.StaticLibrary ( target = buildpath + '/libprecice', source = [sourcesPreCICE] ) env.Alias("staticlib", staticlib) solib = env.SharedLibrary ( target = buildpath + '/libprecice', source = [sourcesPreCICE] ) env.Alias("solib", solib) Both have BOOST_LOG_DYN_LINK set: env.Append(CPPDEFINES=["BOOST_LOG_DYN_LINK"]) However, I wonder if this is correct. Should DYN_LINK only be set when building the dynamically linked lib? Thanks, Florian

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Update the index of a hashed_non_unique entry in boost::multiindex
by Ram 24 Oct '16

24 Oct '16

I have a boost::multiindex container which has an index as follows : boost::multi_index::hashed_non_unique< boost::multi_index::tag<IndexByNonUniqueId>, boost::multi_index::const_mem_fun<StoredObj, std::string, &StoredObj::getNonUniqueIdString> > This ID comes in as ""(empty string) when I initially get the object. I add it to the multiindex at this point. But later in the course of the program the ID gets populated using its "setNonUniqueId" method. At this point of time inside "setNonUniqueId" I would like to update the index to the object(in the multiindex) as well(while the ID is being updated from "" to something concrete). How do I do this? How do I locate the specific object and update the index? -R

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upgrade from boost 1.39 to boost 1.50. Issue with regex_match
by MAURICE Jean 21 Oct '16

21 Oct '16

Hi, I am 'upgrading' a huge C++ app from VS2005 (32bits) to VS2010 (64 bits) and boost 1.39 to boost 1.50. This app runs both under Windows and Linux. In a function that searchs subdirectories and files of a given directory, we get the list of all the elements and then this list is filtered by : if(true==boost::regex_match(sAdaptation, what, childNode.infoNode.rFullPathFilePattern)) sAdaptation is ".\TEST\un_noeud" (this subdirectory exists) childNode.infoNode.rFullPathFilePattern is something like {m_pimpl={...}} And regex_match always returns false. If you can give me information about what is happening ... Jean

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build boost 1.58 failed on centos 7.2
by Glenn WANG 20 Oct '16

20 Oct '16

hi, I try to build boost 1.58 on CentOS, but it cannot be done, there're many errors. could anybody help? thanks. ============================== ./b2 --with-log -q gcc.compile.c++ bin.v2/libs/system/build/gcc-4.8.5/release/threading-multi/error_code.o In file included from libs/system/src/error_code.cpp:19:0: ./boost/system/detail/error_code.ipp:48:27: error: expected ‘;’ at end of member declaration const char * name() const BOOST_SYSTEM_NOEXCEPT; ^ ./boost/system/detail/error_code.ipp:48:33: error: ‘BOOST_SYSTEM_NOEXCEPT’ does not name a type const char * name() const BOOST_SYSTEM_NOEXCEPT; ^ ./boost/system/detail/error_code.ipp:56:32: error: expected ‘;’ at end of member declaration const char * name() const BOOST_SYSTEM_NOEXCEPT; ^ ./boost/system/detail/error_code.ipp:56:38: error: ‘BOOST_SYSTEM_NOEXCEPT’ does not name a type const char * name() const BOOST_SYSTEM_NOEXCEPT;

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Boost Coroutine
by Miguel Portilla 19 Oct '16

19 Oct '16

Hello, Using Boost 1.62, I am seeing the following warning when I build my project. warning : Boost.Coroutine is now deprecated. Please switch to Boost.Coroutine2. To disable this warning message, define BOOST_COROUTINE_NO_DEPRECATION_WARNING. I haven't found any documentation on what exactly this means or how to 'switch'. Can someone please point me to some docs or explain what 'switching' entails? Thanks, -M

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Re: [Boost-users] [Boost-build] [System] Link issues using BOOST_ERROR_CODE_HEADER_ONLY
by Matthias Seemann 17 Oct '16

17 Oct '16

Hi, > We decided to fix these by defining the macro BOOST_ERROR_CODE_HEADER_ONLY > according to this link: > > http://www.boost.org/doc/libs/1_56_0/libs/system/doc/reference.html#Header-… > > However, when building Boost itself with this macro defined, we're > encountering several problems: > ... > 2) We get multiple definitions of "boost::system::throws" > Defining the macro BOOST_SYSTEM_NO_DEPRECATED (see that doc page above) resolved the issue of multiple definitions of "boost::system::throws". Matthias

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boost graph pruning vertices (nodes)
by Brian Davis 14 Oct '16

14 Oct '16

In reading http://www.boost.org/doc/libs/1_62_0/libs/graph/doc/adjacency_list.html regarding Iterator and Descriptor Stability/Invalidation it leaves the impression that when using vecS there is no real good way to remove nodes. as example: typedef adjacency_list<listS, vecS> Graph; // VertexList=vecS all cases are wrong and typedef adjacency_list<listS, listS> Graph; // VertexList=listS where only one case is correct which leave the programmer walking the mine field. Of course same can be said for stl. My goal to remove graph vertices based on the value of the connected components. I currently have a method which uses connected components to generate a connected components list. I then generate a histogram of the connected components values thus giving me how many vertices are connected and what the connection property value is... assuming I understand connected components however I have thought I understood portions of boost only to find through some brain warp and folding my thought process back on itself like an origami master that I came to understand how certain parts work. vertid, component 0 0 1 0 2 0 3 0 4 1 5 1 6 2 7 2 8 2 9 2 10 2 11 2 12 3 13 3 so in this simple example vert ids [0-3] are connected in subnet 0 with a total of 4, [4-5] are connected in sub net 1 with a total of 2, [6-11] are connected in subnet 2 with a total of 6, and [12-13] is connected in subnet 3 with a total of 2. Histogram yields connected component value and number of vertices that have that value in the bin component : bin counts 0: #### 1: ## 2: ###### 3: ## etc for say subnet/subgraph less than 4 would yield the filtered histogram: 1: ## 3: ## using values 1, and 3 from filtered histogram I can then find the vertex ids to filter. Yielding vertices 4,5,12, and 15 to be removed which would remove subnets 1 and 3. 4 1 5 1 12 3 13 3 I tried to use boost::accumulators::density and maybe I have a different idea of what a histogram really is, but for a typical histogram density is just plane broken due to the seemingly use of count for number of bins (seems to ignore tag::density::num_bins) and associated logic. accumulator_t acc( tag::density::num_bins = n_bins, tag::density::cache_size = n_bins/2 ); Sure wish there was a boost::accumulators::histogram that just did what we need as programmers. I am unsure as to how much boost coolaid to drink before finding any use for density. I did find this relating to the seemingly not as advertised implementation of density http://lists.boost.org/Archives/boost/2008/01/132801.php. From http://www.boost.org/doc/libs/1_62_0/doc/html/accumulators/user_s_guide.html "The tag::density feature returns a histogram of the sample distribution. For more implementation details, see density_impl." err huh no it does not... at least in my testing. It would also be great if the abcicissas (intervals) were some how obtainable to compare to the ordinates (bin counts) . Note the histogram.hpp attached there. So I write by own histogram code using stl. I digress on that. So as I said I then filter the vertex vs connected components data based on a threshold say 4 to remove all vertices that are not connected to 4 or more vertices in a subnet/subgraph So I then have a list of vertices (subnets/subgraphs) that I wish to prune from the graph thus these questions: Question 1: if finding a list of vertices to erase, sorting them, and then using, a reverse iterator to remove(*itr, g) would this also not work? If this works why is it now shown as an example of vecS vertex removal working? Question 2: Should there not be a boost graph-ish way of doing this such as coloring vertices to be pruned by possibly adding property prune = true. then maybe a future call to prune(g) Question 3: Possibly there is a way to get filtered_graph to do the trick? Statement: it is unfortunate the use of the term vertex/vertices in stead of node(s) in boost graph. As some graphs have a vertex (euclidean geometry) such as a graph of the center-lines of the vascular network of a brain while other graphs do not. It is very confusing in this instance to keep the two strait in code. Ugh!

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Re: [Boost-users] [Serialization] Free-standing serialize function for "enum class"
by Bjorn Reese 13 Oct '16

13 Oct '16

On 10/13/2016 06:56 PM, Rüdiger Berlich wrote: > I have for a while suspected a problem with the serialization of an „enum class“ item (currently with Boost 1.61 on Ubuntu 16.04), and have written a small test program to further examine any potential problems. While the generated XML looks fine and I cannot see any problems with the enum class, my custom, free-standing „serialize“ function does not get called. Boost.Serialization automatically converts an enum into an int before it is serialized.

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[Serialization] Free-standing serialize function for "enum class"
by Rüdiger Berlich 13 Oct '16

13 Oct '16

Hi there, I have for a while suspected a problem with the serialization of an „enum class“ item (currently with Boost 1.61 on Ubuntu 16.04), and have written a small test program to further examine any potential problems. While the generated XML looks fine and I cannot see any problems with the enum class, my custom, free-standing „serialize“ function does not get called. It is modelled after the examples for non-intrusive serialization, so I do not understand the reason behind this. Any idea ? /*************************************/ // Compile with g++ --std=c++14 -o enum_ser -I/opt/boost/include/ -L/opt/boost/lib enum_ser.cpp -lboost_serialization #include <boost/serialization/nvp.hpp> #include <boost/archive/xml_oarchive.hpp> #include <boost/archive/xml_iarchive.hpp> #include <iostream> #include <sstream> enum class test_enum : int {a=5,b=6}; namespace boost { namespace serialization { //----------------------------------------- template<typename Archive> void serialize(Archive &ar , test_enum &x, const unsigned int){ std::cout << "Serializing via custom serialize function" << std::endl; int t = 0; if (Archive::is_saving::value) { t = static_cast<int>(x); ar & t; } else { ar & t; x = static_cast<test_enum>(t); } } //----------------------------------------- } } int main(int argc, char **argv){ std::ostringstream oss; test_enum x = test_enum::a; { boost::archive::xml_oarchive oa(oss); oa << BOOST_SERIALIZATION_NVP(x); } std::cout << oss.str() << std::endl; } /*************************************/ Output of the program (note: the „Serializing via custom serialize function“ does not appear) : /*************************************/ <?xml version="1.0" encoding="UTF-8" standalone="yes" ?> <!DOCTYPE boost_serialization> <boost_serialization signature="serialization::archive" version="14"> <x>5</x> </boost_serialization> /*************************************/ Thanks and Kind Regards, Beet

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