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Serialization to human-readable formats
by Mateusz Loskot 28 Oct '10

28 Oct '10

Hi, I have a library reading/writing data from binary files. The library defines collection of type representing schema and data stored in the files. Definition of those elements is versioned, so one file can be slightly different than other. The de-/serialization from/to those files is implemented, so it's not part of my problem. I'm looking for recommendation of tools to based implementation of serialization of those objects to/from human-readable format like XML, JSON, other text-based formats. I'm looking for non-intrusive solution with degree of extensibility, so new formats can be added if needed. Ideally, if the mechanism could be aware of the versions of objects being serialized. I have never used the Boost Serialization library, but reading its documentation suggests it may fit the problem well. UDT can be instrumented with serialization mechanism in non-intrusive way. There are some archivers provided and, as far as I understand, new can be added. There are also other tools like Boost Property Tree or even Spirit Qi/Karma which technically could do the job, I think. There is also this naive option dangling around, which is implementation of << and >> operators for my types. Hoping I've described what I need fairly well, I'd like to ask for some suggestions which option sounds better. Perhaps I've missed some details or possibilities, thus any brainstorming is welcome. Best regards, -- Mateusz Loskot, http://mateusz.loskot.net Charter Member of OSGeo, http://osgeo.org Member of ACCU, http://accu.org

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[serialization] compile error on Mac OSX Tiger
by Philipp Münzel 27 Oct '10

27 Oct '10

Hi folks, after successfully deploying boost 1.44 on Windows and Linux, I now fail bitterly on Mac OSX. It is a Power PC with OSX 10.4 and gcc 4.0.1 When building boost with the following command: ./bjam --layout=system --with-serialization link=static variant=release threading=multi I get the following error: darwin.compile.c++ bin.v2/libs/serialization/build/darwin-4.0.1/release/link-static/threading- multi/basic_xml_archive.o darwin.compile.c++ bin.v2/libs/serialization/build/darwin-4.0.1/release/link-static/threading- multi/binary_iarchive.o ./boost/archive/basic_binary_iarchive.hpp:74: error: invalid application of 'sizeof' to incomplete type 'boost::STATIC_ASSERTION_FAILURE<false>' "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -no-cpp-precomp -gdwarf-2 -Wno-long-double -DBOOST_ALL_NO_LIB=1 -DNDEBUG -I"." -c -o "bin.v2/libs/serialization/build/darwin-4.0.1/release/link-static/threading- multi/binary_iarchive.o" "libs/serialization/src/binary_iarchive.cpp" ...failed darwin.compile.c++ bin.v2/libs/serialization/build/darwin-4.0.1/release/link-static/threading- multi/binary_iarchive.o... ...failed updating 1 target... ...updated 74 targets... I did NOT set architecture=combined. I want a PPC only build. Any help is greatly appreciated. Regards Philipp

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[mpl] Accessing the nested value of an invoked placeholder
by Nathan Crookston 27 Oct '10

27 Oct '10

All, I'm writing some code to filter a vector_c of enum values. I have some existing structs which are templatized on those enum types and I'm having some trouble accessing those structs using placeholders. Following is code which hopefully clarifies: #include <boost/cstdint.hpp> #include <boost/mpl/assert.hpp> #include <boost/mpl/copy_if.hpp> #include <boost/mpl/vector_c.hpp> #include <boost/type_traits.hpp> #include <iostream> using boost::mpl::placeholders::_; enum MyEnum { val1, val2, }; template <MyEnum me> struct trait; template <> struct trait<val1> { typedef boost::uint16_t type; }; template <> struct trait<val2> { typedef boost::uint8_t type; }; //PROBLEM: The 'T' passed in is _, not what it substitutes for. template <typename T> struct traitMeta : trait<T::value> {}; typedef boost::mpl::vector_c<MyEnum, val1, val2> Vec; //For each item in Vec, determine if trait<_>::type matches T. If so, add it. template <typename T> struct TypeIs : boost::mpl::copy_if<Vec, boost::is_same<typename traitMeta<_>::type, T> > {}; BOOST_MPL_ASSERT((TypeIs<boost::uint16_t>::type, boost::mpl::vector_c<MyEnum, val1>)); int main() { return 0; } //END CODE I would assume from reading the book and documentation that mpl::apply or mpl::lambda would be best to use here, but my attempts to do so haven't been successful. I'd appreciate any guidance. Thanks, Nate

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[thread] recursive shared mutex
by JOAQUIN M. LOPEZ MUÑOZ 27 Oct '10

27 Oct '10

Hi, Boost.Threads provides a recursive mutex and a shared mutex, but no recursive *and* shared mutex. Would it be a good idea to add this to the library? How hard is it to construct a recursive shared mutex from boost::sahred_mutex (i.e. adding reentrancy to boost::shared_mutex)? Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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load a serialized object into Matlab?
by James C. Sutherland 27 Oct '10

27 Oct '10

I am just looking into the serialization library. It seems really nice for archiving using C++. Is there a way to import an archive generated by that library into another language (e.g. matlab)? I guess that one would need the rules for IO that the serialization archives use? Thanks, James

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Boost::Log named_scope issue
by Kieran Parsons 27 Oct '10

27 Oct '10

Can someone give me a working example of using named_scope for Boost::Log? I have tried something like: boost::shared_ptr< boost::log::core > logCore = boost::log::core::get(); logCore->add_global_attribute("Scope", boost::make_shared< boost::log::attributes::named_scope >()); boost::shared_ptr< boost::log::sinks::synchronous_sink< boost::log::sinks::text_file_backend > > sink = boost::log::init_log_to_file("myfile.txt"); sink->locked_backend()->set_formatter ( boost::log::formatters::stream << boost::log::formatters::named_scope( "Scope", keywords::iteration = boost::log::formatters::reverse, keywords::delimiter = " | ") ); logCore->add_sink(sink); BOOST_LOG_FUNCTION(); BOOST_LOG_NAMED_SCOPE("MyScope"); boost::log::sources::logger lg; BOOST_LOG(lg) << "TEST"; But it fails with an exception during the BOOST_LOG (I think due to missing attribute). As a general comment, the fact that none of the tutorial examples in the documentation work as-is makes it extremely difficult for a newbie to use (namespaces undefined, lack of include files etc). Thanks for your help.

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Function pointer to in/out_degree in BGL
by langermatze 27 Oct '10

27 Oct '10

Hi, I have a question regarding the boost graph library. I'd like to write a set of depth first search visitors to determine the maximum in/out-degree of a graph. The code should look pretty similar for both cases except for the function call to get the property of the visited node. boost:in_degree(node_id, graph) vs. boost:out_degree(vertexId, graph) At first glance the function signature pretty much the same, maybe: template<class Graph> graph_traits<Graph>::degree_size_type function(graph_traits<Graph>::vertex_descriptor u, const Graph &g) When looking at the BGL headers however, things seem to be a bit more complex, though. I tried to implement a generic dfs_visitor taking a general function pointer to get the in/out degree property of the visited node but I couldn't work out the type of the function pointer to be passed. All my attemtps failed badly. Hopefully, there is anybody on this list who has a better understanding of this business and could provide some help. Any hints/comments are appreciated! Thank you so much, Matthias -- View this message in context: http://boost.2283326.n4.nabble.com/Function-pointer-to-in-out-degree-in-BGL… Sent from the Boost - Users mailing list archive at Nabble.com.

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boost::thread within a dll
by Matheus Araújo Aguiar 27 Oct '10

27 Oct '10

Hello list, I'm facing some problems with a dll that uses boost::thread, boost::mutex and boost::condition_variable. Currently i am clueless about what is causing the problem and wanted to know if it is ok to use boost::thread and the others aforementioned within a dll. Basically, in a singleton in the dll, some threads are created and consume tasks (wrapped with boost::bind) from a queue, using boost::mutex to avoid concurrency problems and boost::condition_variable to sleep and wake, depending on emptiness of the task queue. Sorry for the brief and rapid description of my problem. Could anyone point to me if using these might cause problems with dlls? Thank you all, -- Matheus Araújo Aguiar Computer Scientist matheus.pit(a)gmail.com

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Boost XML compile problem XML_SAVE_FORMAT
by Kraus Philipp 27 Oct '10

27 Oct '10

Hello, I would like to use the Boost XML structure. Is the package within the SVN compatible under OSX, Linux and MS Windows? I'm using it at the moment under OSX, but I must use the code later under Linux and Windows. Under OSX I use the libxml2 Library, but in the boost/xml/dom/io.hpp I get an compile error on line 36 "xmlSaveCtxt *ctx = xmlSaveToIO (detail::stream_write_callback, detail::stream_close_callback, sb, enc, XML_SAVE_FORMAT);" the XML_SAVE_FORMAT isn't defined (message: not declared in this scope). My problem is at this time, that I must parse XML data of a stream objekt on-fly and extract some nodes (and this with a cross-plattform library). Is this the correct way to do the parsing with Boost XML? Thanks Phil

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[geometry][ggl] boost array adapted mechanism
by alfC 27 Oct '10

27 Oct '10

The documentation of GGL (Generic Geometry Library) is still scattered and hard to follow. As usual the first test I do on a library is to see how well it can be adapted to existing code. GGL seems to be able to adapt c_arrays and tuples as nD points. I was wondering if boost::array and fusion::vector can be adapted as well. The manual says it is but the header file boost/geometry/geometries/adapted/boost_array_as_ring.hpp doesn't seem to have that purpose. In the following example, p4 doesn't work as a point #include<boost/geometry/geometry.hpp> #include<boost/geometry/geometries/cartesian3d.hpp> #include<boost/geometry/geometries/adapted/boost_array_as_ring.hpp> #include <boost/geometry/geometries/adapted/c_array_cartesian.hpp> #include <boost/geometry/geometries/adapted/tuple_cartesian.hpp> #include<iostream> int main(){ using namespace boost::geometry; point<double, 3, cs::cartesian> p1(1,2,3); double p2[3] = {4,5,6}; boost::tuple<double, double, double> p3(7,8,9); boost::array<double, 3> p4={{10,11,12}}; std::clog << distance(p1,p2) << std::endl; std::clog << distance(p2,p3) << std::endl; std::clog << distance(p3,p4) << std::endl; return 0; } In other words, why there is not boost/geometry/geometries/adapted/boost_array_cartesian.hpp ? And it indeed this adaptation of boost::array is not included in the library, what steps should I follow to make a boost::array adapted to GGL? Thank you, Alfredo

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