- Boost-users - lists.boost.org

[utility] BOOST_IDENTITY_TYPE drops const-ness of value types
by Nick Stokes 29 Apr '16

29 Apr '16

Looks like const value types, once passed thru BOOST_IDENTITY_TYPE, "becomes" non-const. Like so: // Attempt to implement a multi-argument utility macro, where arguments are // types, parenthesized only when required (by the user, when type has commas) #define ASSERT_EQUAL( t1, t2 ) \ static_assert( std::is_same< \ BOOST_IDENTITY_TYPE((t1)), BOOST_IDENTITY_TYPE((t2)) \ >::value, #t1 " not same as " #t2) // sanity check: static_asserts as expected ASSERT_EQUAL( int, double ); // sanity check: static_assert as expected for types with commas ASSERT_EQUAL( (std::pair<int, double>), (std::pair<double, int>) ); // Here is the failure: this is expected to assert but it doesnt! ASSERT_EQUAL( const int, int ); >From the implementation of BOOST_IDENTITY_TYPE, it is clear why this is happening, as the function signature is independent of const-ness of value type. Is this a bug? Or is this not the way BOOST_IDENTITY_TYPE is supposed to be used? Nick

1 0

linking and including in visual studio
by David Medine 29 Apr '16

29 Apr '16

This is kind of a stupid question, and maybe more of a Windows/Visual Studio question than a boost one, but this has been troubling the back of my mind lately. Having learned to write and compile C++ code on Linux, I am always in the habit of explicitly stating the include and library paths for the compiler to search for, as well as the libraries themselves that need to be linked. However, I am revising some Visual Studio projects that use boost and I realized that the path I gave for 'Additional Library Directories' is $(BOOST_ROOT)/lib, but my version of boost hasn't got this directory (it's actually $(BOOST_ROOT)\libs). I then removed all references to boost from 'Additional Library Directories', and 'Additional Include Directories' and the application builds and runs swimmingly. This leads me to believe, that assigning the BOOST_ROOT environment variable in Windows is the only step that is needed for VS's auto linking magic to link correctly to boost. Am I right here, or is there something I am missing? Cheers, David

7 14

Date and Time with Boost
by Counter Wall 28 Apr '16

28 Apr '16

What I want to do is read a text file containing a text string in ISO 8601 combined date and time in utc format (e.g. 2016-04-26T12:45:05+00:00). I also want to have the freedom to convert this between time zones and have accurate daylight savings time data. Boost::datetime seems to read in the string, but it looks like boost::locale is recommended for time zone conversions and DLS. Is there a way for me to have both?

2 1

Re: [Boost-users] [boost.multiprecision] export_bits throws on a negative number
by Tassilo Glander 28 Apr '16

28 Apr '16

Hi John, thanks for stepping in. I would expect that the export just exports the memory representation of the number - maybe with flipped order via msv_first parameter. Especially, something exported via export_bits and than imported via import_bits should be the same, at least on the same platform. That said, I actually was just looking for a way to implement a hash function and thought it was straightforward to use chunks of char. But I could also compute the hash on the str() output. Tassilo

2 1

[boost.multiprecision] export_bits throws on a negative cpp_int number
by Tassilo Glander 28 Apr '16

28 Apr '16

Dear List, When calling export_bits on a negative boost::multiprecision number based on cpp_int, an exception is thrown from the internal method msb ("testing individual bits in negative values is not supported"). boost::multiprecision::checked_int128_t i (-1); // use negative number std::vector<unsigned char> v; export_bits(i, std::back_inserter(v), 8); // throws How can I extract the content of a boost::multiprecision number? Boost documentation says, export_bits is designed to be used for data exchange, so in my understanding it would be a major flaw, if it cannot export supported values. I learnt that a workaround might be to directly access the backend's limbs, but this way I am accessing internals that may change. http://www.boost.org/doc/libs/master/libs/multiprecision/doc/html/boost_mul… I also asked this on http://stackoverflow.com/questions/36890928/boostmultiprecisionexport-bits-…, but this list is probably the better place. Thanks, Tassilo

2 1

[PBGL] compilation of example/dijkstra_shortest_paths.cpp failed
by Eisuke Kawashima 27 Apr '16

27 Apr '16

Dear all, I tried to compile http://www.boost.org/doc/libs/1_60_0/libs/graph_parallel/example/dijkstra_sh ortest_paths.cpp, an example code of Parallel Boost Graph, resulting in faulure; example/breadth_first_search.cpp has no problem. My environment is: * GCC 4.9.2 * OpenMPI 1.10.2 * boost 1.60.0 * OS: Debian jessie The error, related to template, is long; the summary is: $ mpicxx -std=c++11 -lboost_mpi -lboost_serialization -lboost_system - lboost_graph_parallel dijkstra_shortest_paths.cpp In file included from boost/graph/dijkstra_shortest_paths.hpp:25:0, from dijkstra_shortest_paths.cpp:19: boost/pending/relaxed_heap.hpp: In instantiation of ‘bool boost::relaxed_heap... boost/graph/distributed/crauser_et_al_shortest_paths.hpp:377:54: required from ... boost/graph/distributed/detail/remote_update_set.hpp:148:7: required from ... boost/graph/distributed/crauser_et_al_shortest_paths.hpp:264:37: required from ... boost/graph/breadth_first_search.hpp:76:7: required from ... boost/graph/breadth_first_search.hpp:124:69: required from ... boost/graph/breadth_first_search.hpp:135:64: [ skipping 4 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ] boost/graph/distributed/dijkstra_shortest_paths.hpp:146:50: required from ... boost/graph/distributed/dijkstra_shortest_paths.hpp:200:45: required from ... boost/graph/dijkstra_shortest_paths.hpp:573:16: required from ... boost/graph/dijkstra_shortest_paths.hpp:595:35: required from ... boost/graph/dijkstra_shortest_paths.hpp:614:14: required from ... dijkstra_shortest_paths.cpp:74:64: required from here boost/pending/relaxed_heap.hpp:194:70: error: cannot convert ‘const value_type {aka const boost::optional<boost::detail::parallel::global_descriptor<long unsigned int> >}’ to ‘bool’ in return bool contains(const value_type& x) const { return groups[get(id, x)]; } ^ "-ftemplate-backtrace-limit=0" flag did not work. How to fix this? -- Eisuke Kawashima

2 4

[boost-users][boost graph] edge_descriptor problem when copy from original graph
by Emerson Xu 26 Apr '16

26 Apr '16

Hi all, I have a boost graph copy problem that has been nagging me for a long time. My question is, is there anyway that I can construct a graph once, and reuse it multiple times, each time I may mutate the graph a bit. I have a class, which creates a boost graph with bundled vertex and edge properties (my own properties, vertices are routers in a network, while edges are logical links between routers). When creating the graph, some helper unordered maps are also created, like mapping from an edge_descriptor to a logical link name, from a router name to a vertex_descriptor, etc. Now there are multiple clients calling some method in the class. Current strategy is to construct a new boost graph instance for every client, and run the service on each graph instance. Now I want to improve the performance by avoiding constructing the graph for every client ( >100 clients are calling it simultaneously). So I am thinking that we can initialize only one base graph, and make it a copy for every client. Then the problem comes, since in the method the client needs use those helper unordered maps, but the data inside the maps are from that original base graph. Even if I use a copy constructor(deep copy) for each graph copy, some graph data is still inconsistent, like the edge_descriptor, for example, I can't use the hashmap with edge_descriptor as key, because this edge_descriptor only points to the memory address of base graph. Best, Emerson

2 1

error when copying blocks into a dynamic_bitset
by Diab Jerius 26 Apr '16

26 Apr '16

Hi, I'm trying to initialize a dynamic_bitset<unsigned char> from a vector of blocks. Here's the code: #include <cstdlib> #include <vector> #include <boost/dynamic_bitset.hpp> typedef boost::dynamic_bitset<unsigned char> BitSet; typedef std::vector<BitSet::block_type> Block; int main(int argc, char* argv[]) { int nbits = atoi( argv[1] ); BitSet bits( nbits ); Block buffer; buffer.resize( bits.num_blocks(), 0xff ); boost::from_block_range(buffer.begin(),buffer.end(), bits ); return 0; } If the bitset size isn't a multiple of sizeof(unsigned char) (here 8) , ~dynamic_bitset() throws an exception. For example: % ./a.out 1 a.out: boost-1.60.0/include/boost/dynamic_bitset/dynamic_bitset.hpp:633: boost::dynamic_bitset<Block, Allocator>::~dynamic_bitset() [with Block = unsigned char; Allocator = std::allocator<unsigned char>]: Assertion `m_check_invariants()' failed. Aborted % ./a.out 8 % ./a.out 15 a.out: boost-1.60.0/boost/dynamic_bitset/dynamic_bitset.hpp:633: boost::dynamic_bitset<Block, Allocator>::~dynamic_bitset() [with Block = unsigned char; Allocator = std::allocator<unsigned char>]: Assertion `m_check_invariants()' failed. Aborted % ./a.out 16 % I see this with 1.59 & 1.60 using either g++ 4.7.2 or Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn) I believe that I'm following the rules for the buffer type and size. Is there something I'm missing? Thanks! Diab

1 0

Compiler errors using boost/program_options with Boost v 1.53 and v 1.59
by Christine Peters 26 Apr '16

26 Apr '16

Dear all, I had to reinstall my boost version as the cluster environment I'm working on has switched from Scientific Linux 6 to CentOS 7. When I'm now compiling my code including the header "#include <boost/program_options>", I will receive the following error message: In file included from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/mpl/aux_/arithmetic_op.hpp:34:0, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/mpl/times.hpp:19, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/mpl/multiplies.hpp:17, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/numeric/conversion/detail/is_subranged.hpp:17, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/numeric/conversion/detail/conversion_traits.hpp:21, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/numeric/conversion/conversion_traits.hpp:13, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/numeric/conversion/converter.hpp:13, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/numeric/conversion/cast.hpp:33, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/lexical_cast/detail/converter_numeric.hpp:37, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/lexical_cast/try_lexical_convert.hpp:34, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/lexical_cast.hpp:32, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/program_options/value_semantic.hpp:14, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/program_options/options_description.hpp:13, from /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/program_options.hpp:15, from /home/cp652127/EclipseWorkspace/AMD-Geant4.10/amd/externals/g4sipm/sample/include/ParticleSourceMessenger.hh:24, from /home/cp652127/EclipseWorkspace/AMD-Geant4.10/amd/externals/g4sipm/sample/include/AsciiPersistencyHandler.hh:20, from /home/cp652127/EclipseWorkspace/AMD-Geant4.10/amd/externals/g4sipm/sample/include/RunAction.hh:16, from /home/cp652127/EclipseWorkspace/AMD-Geant4.10/amd/externals/g4sipm/sample/src/RunAction.cc:9: /home/phys3aauger/tine/ApeInstalled/External/boost/1_59_0/include/boost/mpl/aux_/include_preprocessed.hpp:37:90: fatal error: boost/mpl/aux_/preprocessed/gcc/ostimes.hpp: No such file or directory # include BOOST_PP_STRINGIZE(boost/mpl/aux_/preprocessed/AUX778076_PREPROCESSED_HEADER) ^ compilation terminated. This fatal error occurs with my own boost installation (version 1.59.0) but also with the system default boost (version 1.53.0). It worked properly on Scientific Linux 6. Now, I'm using gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4), CPU codename Intel Nehalem EX, LINUX, CENTOS 7.2 environment. I would be very glad if someone could help me. It seems that somehow the AUX778076 parameter defined in "boost/1_59_0/include/boost/mpl/times.hpp" is converted to ostimes during the compilation: I've changed, just for testing reasons!, in file "/boost/1_59_0/include/boost/mpl/times.hpp" the line "#define AUX778076_OP_NAME times" to "#define AUX778076_OP_NAME timestest" and then boost is searching for the correct header "timestest.hpp" but in the case of "#define AUX778076_OP_NAME times" it is searching for "ostimes.hpp" instead of "times.hpp". Thanks in advance for your help! Cheers, Christine

2 2

Typo in BGL Subgraph
by Eisuke Kawashima 23 Apr '16

23 Apr '16

Dear all, I submitted the following to boost-docs but have received no response, so also submitting to boost-users. The last part of Boost Graph Library: Subgraph <http://www.boost.org/doc/libs/release/libs/graph/doc/subgraph.html> (since Boost 1.40) > > struct my_vertex { ... }; > typedef property<vertex_index_t, std::size_t, vertex_prop> vertex_prop; > struct my_edge { ... }; > typedef property<edge_index_t, std::size_t, vertex_prop> edge_prop; should be > > struct my_vertex { ... }; > typedef property<vertex_index_t, std::size_t, my_vertex> vertex_prop; > struct my_edge { ... }; > typedef property<edge_index_t, std::size_t, my_edge> edge_prop; Additionally I want you to note how to modify GraphProperties of boost::subgraph (or whether it is not implemented). Regards, -- Eisuke Kawashima email: e.kawaschima(a)gmail.com

2 2