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Tree library?
by Germán Diago 31 Jan '09

31 Jan '09

Is there any library in preparation in boost to use tree data structures? If not, I would like to know where I can find a good implementation of any open source tree library. I found this one, but I'm not sure if it's good quality. It seems to be: http://www.aei.mpg.de/~peekas/tree/ Thanks for your time.

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[gil] bad_cast exception
by Olivier Tournaire 30 Jan '09

30 Jan '09

Hi all, I am trying to use GIL and face a problem. Here is the code : namespace boost { namespace gil { /// Extension a GIL pour gerer les pixels "double" ... typedef pixel< double, boost::gil::gray_layout_t > gray64_pixel_t; typedef image< gray64_pixel_t, false > gray64_image_t; typedef image< gray64_pixel_t, true > gray64_planar_image_t; //typedef image_view< gray64_pixel_t > gray64_view_t; } } int main ( int argc , char **argv) { typedef boost::mpl::vector< boost::gil::gray8_image_t, boost::gil::gray16_image_t, boost::gil::gray32_image_t, //boost::gil::gray64_image_t, boost::gil::rgb8_image_t, boost::gil::rgb16_image_t, boost::gil::rgb32_image_t > my_img_types; typedef boost::mpl::vector< boost::gil::gray8_view_t, boost::gil::gray16_view_t, boost::gil::gray32_view_t, //boost::gil::gray64_view_t, boost::gil::rgb8_view_t, boost::gil::rgb16_view_t, boost::gil::rgb32_view_t > my_view_types; if ( argc < 4 ) { usage(); return 1; } std::string input_filename( argv[1] ); std::string output_filename( argv[3] ); int channel_index; try { channel_index = boost::lexical_cast<int>( argv[2] ); } catch( boost::bad_lexical_cast &e) { std::cout << "bad_lexical_cast exception : " << e.what() << std::endl; return 1; } boost::gil::any_image<my_img_types> runtime_image; boost::gil::any_image_view<my_view_types> runtime_view; try { boost::gil::jpeg_read_image( input_filename , runtime_image ); runtime_view = boost::gil::nth_channel_view( const_view(runtime_image) , channel_index ); boost::gil::jpeg_write_view( output_filename , runtime_view ); } catch( std::exception &e ) { std::cout << e.what() << std::endl; return 1; } return 0; } I get an exception on this line : runtime_view = boost::gil::nth_channel_view( const_view(runtime_image) , channel_index ); However, when I write : boost::gil::jpeg_write_view( output_filename , boost::gil::nth_channel_view( const_view(runtime_image) , channel_index ) ); everything goes well. Where is my mistake ? Best regards, Olivier -- Olivier Tournaire MATIS - Institut Géographique National 73, Ave de Paris 94165 St Mandé cedex, France tel: (+33) 1 43 98 80 00 - 71 25 fax: (+33) 1 43 98 85 81

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Thread status
by Jens Luedicke 30 Jan '09

30 Jan '09

Hallo, how can I check if a given thread is runinng/finished/sleeping? Jens

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Re: [Boost-users] RBGL use with BGL minCut() function
by Gianni Loiacono 30 Jan '09

30 Jan '09

Hi Mr. Sutton thanks for the answer. I didn't know what was **R :-D**. Now I have readed some links and I have understand that RBGL is not adapt for my project (into the file zip Win Binary I have seen a .dll file than I thought that I could use more libraries :)). My goal is to do multi minimum cuts (gomory hu tree algorithm: http://www.corelab.ntua.gr/~syrganis/sources/Gomory-Hu.pdf ). The min-cut BGL functions give out only the min-cut value, I want to know what edges were cut. Can you help me? Sorry for my english ;/ Thanks a lot for your time and for the help. Bye.

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building 32 and 64-bit Boost on the same platform
by Damien Hocking 30 Jan '09

30 Jan '09

Hi all, I'm working on a cross-platform project that needs 32 and 64-bit Boost on Windows, Linux and OS X. I can happily build the individual versions on each platform, e.g. bjam --build-dir=./build64 --toolset=darwin address-model=64 architecture=x86 --build-type=complete stage for OS X, but is there a way to get the stage directory renamed to say stage 64 so I can batch all this up and build the 32 and 64-bit versions without any intervention by me? I can write shell or batch scripts to copy or rename the stage directory, but if there's an option in the build system I'd like to know about it. Thanks in advance. Damien

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Flushing a filtering_ostreambuf
by jean-louis.a.leroy＠fortis.com 30 Jan '09

30 Jan '09

I have implemented a stream that sends output to the debugger (using OutputDebugString() in Windows): class debug_output_sink : public boost::iostreams::sink { public: debug_output_sink(int) { } std::streamsize write(const char* s, std::streamsize n); // also tried with: // struct category : boost::iostreams::sink::category, boost::iostreams::flushable_tag { }; // bool flush() { return true; } }; When I use it directly, flush() works fine: stream_buffer<debug_output_sink> debug_streambuf(debug_sink); ostream debug_stream(&debug_streambuf); debug_stream << "test\n"; debug_stream.flush(); // characters appear immediately However, when I put it in a filter, flushing the filter doesn't flush the stream: // scope { stream_buffer<debug_output_sink> debug_streambuf(debug_sink); ostream debug_stream(&debug_streambuf); filtering_ostreambuf filtering_buf; filtering_buf.push(debug_stream); ostream os(&filtering_buf); os << "test"; os.flush(); // nothing filtering_buf.pubsync(); // nothing either filtering_buf.strict_sync(); // still nothing } // characters appear at last ! What I am missing here? Thanks, Jean-Louis Leroy

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enable_if for class members
by Christopher Jefferson 30 Jan '09

30 Jan '09

In a class, I want to have one member function which has different implementations depending on one of the template parameters. I tried to use enable_if template<bool b> struct foo { typename boost::enable_if_c<b, int>::type get_val( ) { return 2; } typename boost::disable_if_c<b, int>::type get_val() { return 3; } }; But when I use foo in code, it doesn't work, complaning that: error: no type named 'type' in 'struct boost::enable_if_c<true, int>' Am I not using enable_if in the correct way? Is there any easy way to do waht I'm trying to do? I used to do this by declaring an inner class and overloading that, but then it is necessary to pass in the class and the code looks very messy. Thanks, Chris

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newbie question - how to test
by Saibal Ghosh 30 Jan '09

30 Jan '09

Hi, I am building BOOST (the libraries) on solaris platform using SunStudio 11 compiler. But how to test whether all libraries are build properly? Does BOOST has some tests which i can run to verify the build ? regards, Saibal

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serialization deserialization through the pointer
by niranjan bangera 30 Jan '09

30 Jan '09

hi all, i am facing some problem in my code. Please help me to tackle it. BOOST Version : 1.36.0 compliler : gnu-gcc-/4.1.1-binutils-2.16.1/x86_64-pc-linux2.4/bin/gcc example of my prog: header: my.h ---- class my { int var1; int var2; structure object; // structure is the some other structure which is defined(i have defied the serialization function for this also... /*serialization function*/ friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int file_version) { ar & var1; ar & var2; ar & object; } }; mymain.cpp ---------- #include "boost/archive/text_iarchive.hpp" #include "boost/archive/text_oarchive.hpp" #include "boost/serialization/access.hpp" #include "boost/serialization/serialization.hpp" #include "boost/serialization/collection_traits.hpp" #include "boost/serialization/utility.hpp" #include "my.h" class mymain { protected: my * ptr; public: void mytake_arch(); void myretrive_arch(); }; void mymain::mytake_arch() { std::ofstream ofs("filename"); { boost::archive::text_oarchive oa(ofs); oa << ptr; } } void mymain::myretrive_arch() { mymain *ptr = NULL; //// Confused in this, This is correct or wrong, if wront what else i can use std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); ia >> ptr; } int main() { mymain obj; obj.mytake_arch(); obj.myretrive_arch(); } Problem: ------- I have some confusion in retriving, Whether the way in which i retrieved is correct or wrong. Any other replacement or modification can be done for the retriving part(myretrive_arch() function). Please let me know. because the retrived ptr(pointer retrived) causes segmentation fault whenenver i use it for some other application. Any suggestions will be apprciated. Thanks, Niranjan

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Cross compiling
by Yepez, Esteban 30 Jan '09

30 Jan '09

Hello, I am trying to cross compile boost for an embedded processor that has its own gcc and g++ compiler. What are the options I need to invoke so that the make uses these compilers instead of gcc? Also, can you tell me the simpliest way to test it? Thanks, Esteban

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