January 2010 - Boost-users - lists.preview.boost.org

mix usage of boost.thread and pthread?
by Hua Su 01 Feb '10

01 Feb '10

Hi all, Is it OK to use both pthread and boost.thread in the same program under linux? E.g., there are two cases: 1. use pthread api to create/join/detach/cancel threads but use boost.thread's mutex/condition_variable etc. to do thread synchronization, and this_thread/sleep/get_id/thread_local_storage etc.. 2. use boost.thread api to create/join/detach/interrupt thread but use pthread api to do thread synchronization. I know boost.thread is a pthread api wrapper under linux, but I'm afraid of that the two cases above aren't safe if boost.thread uses some tricks I don't understand. Would you kindly give any hints? Thanks! Hua

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[property_tree]problem with equal_range
by Ken Murphy 01 Feb '10

01 Feb '10

Hello all, I am getting an error while trying to compile the following program: #include "boost/property_tree/ptree.hpp" int main(int argc, char* argv[]) { boost::property_tree::ptree t; t.equal_range("KEY"); return 0; } Compiler output: 1>c:\hibbettlinux\src\boost-1.41.0\boost\property_tree\detail\ptree_impl 1>emen tation.hpp(448) : error C2039: 'base' : is not a member of 'boost::multi_index::detail::bidir_node_iterator<Node>' 1> with 1> [ 1> Node=boost::multi_index::detail::ordered_index_node<boost::multi_index::deta il::index_node_base<std::pair<const std::string,boost::property_tree::basic_ptree<std::string,std::string>>,std: :allocator<std::pair<const std::string,boost::property_tree::basic_ptree<std::string,std::string>>>>> 1> ] 1> c:\hibbettlinux\src\boost-1.41.0\boost\property_tree\detail\ptree_implementa tion.hpp(444) : while compiling class template member function 'std::pair<_Ty1,_Ty2> boost::property_tree::basic_ptree<Key,Data>::equal_range(const std::basic_string<_Elem,_Traits,_Ax> &)' 1> with 1> [ 1> _Ty1=boost::property_tree::basic_ptree<std::string,std::string>::assoc_itera tor, 1> _Ty2=boost::property_tree::basic_ptree<std::string,std::string>::assoc_itera tor, 1> Key=std::string, 1> Data=std::string, 1> _Elem=char, 1> _Traits=std::char_traits<char>, 1> _Ax=std::allocator<char> 1> ] 1> c:\hibbettlinux\src\platform\vc80\test\test.cpp(9) : see 1> reference to class template instantiation 'boost::property_tree::basic_ptree<Key,Data>' being compiled 1> with 1> [ 1> Key=std::string, 1> Data=std::string 1> ] 1>c:\hibbettlinux\src\boost-1.41.0\boost\property_tree\detail\ptree_impl 1>emen tation.hpp(449) : error C2039: 'base' : is not a member of 'boost::multi_index::detail::bidir_node_iterator<Node>' 1> with 1> [ 1> Node=boost::multi_index::detail::ordered_index_node<boost::multi_index::deta il::index_node_base<std::pair<const std::string,boost::property_tree::basic_ptree<std::string,std::string>>,std: :allocator<std::pair<const std::string,boost::property_tree::basic_ptree<std::string,std::string>>>>> 1> ] I am using boost 1.41 with VC 7.1 Any help is appreciated!!!!!! Ken Murphy

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Mingw: build, install, .LIB files and boost-config?
by John Pye 01 Feb '10

01 Feb '10

Hi all While I'm aware that MinGW is not one of the 'primary' platforms for MinGW, I wanted to ask a few questions to help me in the task of building a binary copy of Boost for this platform that's as good as it can be. Firstly, what would be the correct build commands to build Boost for MinGW such that I end up with both shared libraries and static libraries? What I've worked out so far is shown here: http://ascendwiki.cheme.cmu.edu/Binary_installer_for_Boost_on_MinGW Secondly, to install Boost at an arbitrary path under MinGW, what is the correct BJAM command? On MinGW, I'm not running ./configure, so the suggestions from the Unix build documentation don't make sense. By default under MinGW, if I run "bjam install", my files end up in c:\Boost but I'd like too have another target directory, so that it's possible to build even without write privileges to that folder. Is there such a thing as "bjam --install-prefix=c:/MinGW install"? Is there a way to strip out all the redundant folder levels like "release" and "gcc-mingw-3.4.5" etc? Third, using BJAM on MinGW results in .LIB files being generated. These .LIB files are NOT correctly names for use with MinGW. As far as I can tell, I have to rename them as .A files, or else do something else with them so that they'll correctly be detected by the the GCC "-l" linker flag. Finally, there was a bit of discussion on the mailing list about a year ago about providing a "boost-config" script. With the ever-changing naming conventions for Boost libs, and the possible presence of static libraries, shared libraries, -mt, -d, and other file suffixes, such a script would be INVALUABLE for people looking to access pre-built Boost binaries for their projects. It would be an almost trivial task to implement such a script -- has there been any progress on this anywhere? Can I suggest that for MinGW, a native shell script, with file paths constructed relative to the boost-config path, would probably be the best way, rather than pkg-config, which is not available in MinGW/MSYS by default. Feel free to direct me to the online documentation of this stuff if it exists -- I couldn't find it though. Cheers JP -- John Pye Dept of Engineering Australian National University http://pye.dyndns.org/

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boost serialization stream error question
by Gabe Sibley 01 Feb '10

01 Feb '10

Dear All, I'm using boost serialization and have come across issues with "steam error" when I try to deseriailze from an xml or text archive. Binary archives are fine, but I can't use binary because my users need xml archives. The problem is caused by double values less than DBL_MIN. Apparently, streaming such values in causes the input stream fail_bit to be set, which causes the serialization lib to throw an exception. One work around is to make sure all double values are clamped and finite when the archive is created. I can live with this, esp. since I have algorithms that will from time to time produce non-finite results. So far what I've done is just replace BOOST_SERIALIZATION_NVP macro with the following MAKE_NVP macro that calls "FixReal": #define BOOST_SERIALIZATION_NVP(name) \ boost::serialization::make_nvp(BOOST_PP_STRINGIZE(name), name ) // Use this macro instead of BOOST_SERIALIZATION_NVP because it fixes doubles that are not streamable. // That is, it fixes double values that cause streaming errors. #define MAKE_NVP(name) \ boost::serialization::make_nvp(BOOST_PP_STRINGIZE(name), FixReal(name) ) // note the call to FixReal // does nothing -- just pass all non-double types through template<class T> inline T& FixReal( T& t ) { return t; } /// Routine to make sure doubles are streamable -- Nan, Inf, etc. cause stream errors, so we prevent them. inline double& FixReal( double& d ) { if( d < DBL_MIN ) { d = DBL_MIN; } if( d > DBL_MAX ) { d = DBL_MAX; } if( std::isnan(d) ) { d = 0; } if( std::isinf(d) ){ d = DBL_MAX; } return d; } /// We also need to fix double arrays. The ugly syntax is because // we have to pass and return a reference to an array. inline double (&FixReal( double (&d)[2] ))[2] { for( size_t ii = 0; ii < 2; ii++ ){ FixReal(d[ii]); } return d; } Ok, here's my question: How can I get the "FixReal" functionality above without having to write a specialized function for every possible double signature? For instance, I don't want to have to write inline double (&FixReal( double (&d)[3] ))[3] inline double (&FixReal( double (&d)[4] ))[4] ... etc. or any of the other POD double signatures possible. I just want the serialization library to fix the errant double values when I create the archive. I guess I could modify the "void save(const double t)" function in basic_text_oprimitive.hpp to check all doubles, but that seems like a bad plan. Any suggestions? thanks for your help, Gabe

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Strange output from boost::exception diagnostic_information
by pholding 01 Feb '10

01 Feb '10

-------------------------------------------------------------------------------- I've been having a look at the diagnostic_information function in the boost exception library, but seem to be getting a strangely formatted output. The code I'm using is as follows Code: #include <boost/exception/diagnostic_information.hpp> #include <stdexcept> #include <iostream> void myerror(){ throw boost::enable_error_info(std::range_error("blah")); } int main(){ try{ myerror(); } catch(boost::exception & e){ std::cerr << diagnostic_information(e) << std::endl; } return 0; }The output is as follows: Quote: Throw in function (unknown) Dynamic exception type: N5boost16exception_detail19error_info_injectorISt1 1range_errorEE std::exception::what: blah What I don't understand is why I'm getting N5, 16, 19, ISt11 and EE between the details of the exception type. To rule out my code, I compiled the example_io.cpp file provided in the boost example documentation and I'm getting a similar output. Does anyone what is causing the strange characters displayed? I'm running Ubuntu 9.10 and the version of g++ is 4.4.1 -- View this message in context: http://old.nabble.com/Strange-output-from-boost%3A%3Aexception-diagnostic_i… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] [BGL] Color Maps
by pablo barrio lópez-cortijo 31 Jan '10

31 Jan '10

Hi Andrew, thanks for your help. > I would recommend using the named parameter version of the call since it lets you omit optional parameters. It seems like the right approach. So now my code is as follows: typedef graph_traits<graph_t>::vertex_descriptor Vertex; Vertex source; ... some code that finds the appropriate vertex // DFSActions is the DFS visitor, with actions on vertex discover and finish DFSActions actions(this); // Calling DFS with named parameters depth_first_search(*g, visitor(actions), root_vertex(source)); Problem: the code doesn't compile, and I'm sure the fault is in "root_vertex(source)". This is the (very synthesized) error thrown by the compiler: property_map.hpp: In instantiation of ‘boost::property_traits<boost::bgl_named_params<long unsigned int, boost::root_vertex_t, boost::no_property> >’: depth_first_search.hpp:192: instantiated from ‘void boost::depth_first_search( long line ) [ with REALLY long line ]’ depth_first_search.hpp:222: instantiated from ‘void boost::depth_first_search( long line ) [ with REALLY long line ]’ graphdef.cpp:134: instantiated from here graphdef.cpp:134: instantiated from here property_map.hpp:31: error: no type named ‘key_type’ in ‘struct boost::bgl_named_params<long unsigned int, boost::root_vertex_t, boost::no_property>’ property_map.hpp:33: error: no type named ‘reference’ in ‘struct boost::bgl_named_params<long unsigned int, boost::root_vertex_t, boost::no_property>’ property_map.hpp:34: error: no type named ‘category’ in ‘struct boost::bgl_named_params<long unsigned int, boost::root_vertex_t, boost::no_property>’ And many other errors, but this is the first one. To check if the problem was in my "source" vertex, I changed the call to DFS with the default value for the root_vertex (looked up in the header file): depth_first_search(*g, visitor(actions), root_vertex(*vertices(*g).first)); The error keeps showing. Having a look at the DFS source code, it seems that the named param function expects a root_vertex of type root_vertex_t, which appears several times in the error msg. The Boost docs specify a type of graph_traits<graph_t>::vertex_descriptor, which is what I'm using now. I suppose it's the same type, but I've not found the type definition. I'm sure it must be a very stupid mistake, but I can't see it. Any clues?

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[circular_buffer] Serialization support for circular_buffer
by Brian Wood 31 Jan '10

31 Jan '10

B"H Shalom, Boost, The C++ Middleware Writer now supports marshalling circular_buffers. This is done by transmitting a circular buffer's capacity, then size, followed by it's elements. An example of the code used when marshalling a circular_buffer is here -- http://webEbenezer.net/posts/cirbuf.hh. -- Brian Wood http://www.webEbenezer.net (651) 251-9384

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Can someone provide an Asio Serial Port example?
by Jeff 30 Jan '10

30 Jan '10

I would like to use Asio to connect to a microcontroller to send and read from, but there are no serial_port samples available. For instance, I would like to type an ‘a’ into the keyboard and have the microcontroller return 1. The microcontroller is already programmed for this but I need to create an interface for it. A sample that does this or any working sample at all would be sincerely appreciated. Thank you, Jeff

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std::list customization
by Etienne Philip Pretorius 30 Jan '10

30 Jan '10

Hello List, I know this is not boost specific, but I would appreciate any comments about the following. I have a specific set of values stored in a std::list<unsigned char>. As expected I can delete and add items anywhere, since I am using the std::list object rearrange its own contents. But here is the problem - when I have already decided that item at position 13 should always remain at position 13 if the list has 13 or more objects in it... If I remove an item from the beginning then the item at position 13 becomes the item at position 12, while this is undesired - the effect of shifting everything else on by one value is desired. Some examples of what I require: Fixed position marked with []. a,b,c,[d],e,f pop_front() is called b,c,e,[d],f This list object should also work when inserting items and keep those with fixed positions at their position if the object size allows it. Any suggestions, Ideas on how to implement this would be greatly appreciated. Kind Regards, Etienne

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[mpl - function_types] Generate typedef from operator() of a functor
by Olivier Tournaire 30 Jan '10

30 Jan '10

Hi all, Given an mpl sequence of types such as: typedef mpl::vector<T0, T1, T2, T3> arg_types; 1) the users of my library provide functors such as F (where T0 and T1 may have been any of the types of arg_types: class F { typedef mpl::pair<T0,T1> signature_type; double operator()(const T0& t0, T1& t1); }; is there a way to generate signature_type automatically ? 2) if the operator() is overloaded, the user class currently has to typedef an mpl::vector of mpl::pairs such as class G { typedef mpl::vector<mpl::pair<T2,T3>, mpl::pair<T1,T1>, mpl::pair<T3,T1> > signature_type; double operator()(const T2& t2, T3& t3); double operator()(const T1& t1, T1& t1); double operator()(const T3& t3, T1& t1); }; in this case, is it also possible to generate signature_type automatically ? Regrads, Olivier

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