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FW: [log] Is there a way to copy the initial log of a rolling log set
by Marc F. Houde 02 Apr '15

02 Apr '15

Greetings, I am using boost::log with a text_file_backend sink with file rotation for logging on a long running application. I have set it up to clear earlier logs when the logging directory reaches a certain size, but I would like to preserve the initial log as it contains useful configuration information that may not be repeated in later logs. I thought I might be able to do this using set_close_handler, and making a copy but there does not appear to be a way to get the actual file information. Thanks, Marc [ASG]<http://www.asg.com/> Marc Houde, Sr Software Engineer marc.houde(a)asg.com<mailto:marc.houde@asg.com> | 703.464.1624 www.asg.com<http://www.asg.com/> | 800.333.8666 USA Only Facebook<https://www.facebook.com/ASGSoftwareSolutions> | LinkedIn<https://www.linkedin.com/company/asg> | Twitter<https://twitter.com/#!/asgsoftware> | YouTube<https://www.youtube.com/asgtech>

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[boost][units] reciprocal conversion / inter unit conversion
by Matthias Wohlgemuth 02 Apr '15

02 Apr '15

Dear users, I just started to use boost::units for some simulations. However, I have some problems with unit conversions and I hope someone can help me. Let's say I have a quantity given in terms of energy in "electron volts" (eV) with the unit "energy". I defined the unit the following: BOOST_UNITS_DEFINE_BASE_UNIT_WITH_CONVERSIONS(si, electron_volts, "electron volts", "eV", PHYSICAL_CONSTANT_DVALUE(e), si::energy, 5000); namespace si { typedef make_system<electron_volts_base_unit>::type electron_volt_system; typedef unit<energy_dimension,si::electron_volt_system> electron_volt_type; BOOST_UNITS_STATIC_CONSTANT(eV,electron_volt_type); } where PHYSICAL_CONSTANT_DVALUE(e) gives me the double representation of si::constants::codata::e.value(). This works fine, for conversions like eV=>Joule etc. (By the way, is there a more straight forward way, to define non-rational scaled units, than defining a new unit sytem?) Now I want to convert eV to nanometers (wavelength) This is defined as: wavelength = c/frequency = h*c/energy (c=speed of light, h = Planck's constant) I would again define a system with the base unit of wavelength and the unit wavelength_type initialized e.g. with wavelength_nanometer. First Problem: What would be the derived dimension/unit: energy, length or a new dimension like wavelength_dimenson? If I would define it as something else than energy, I will have problems when using quantity<si::electron_volt_type>(x*si::wavelength_nanometer) or quantity<si::nanometer_type>(x*si::eV) Second problem: The relationship is reciprocal: wavelength ~ 1/energy. How do I define a proper conversion? Thanks for your help! Cheers, Matthias

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Cross compiling boost 1.55 static libs
by Pham Ngoc Hai 01 Apr '15

01 Apr '15

Hi guys, I'm trying to cross compile boost for armhf but some of the functions seem to be missed.I'm using croos-tool ng, gcc-4.8 =================================For example in file system, boost::filesystem::detail::status is not there: nm stage/lib/linux_armv7/libboost_filesystem.a | grep status [returns nothing] ================================= I take a look on an existing ubuntu.14.04 armhf nm libboost_filesystem.a | grep status 00000048 t _ZN12_GLOBAL__N_113dir_itr_firstERPvS1_PKcRSsRN5boost10filesystem11file_statusES8_.isra.29.constprop.49 00001cf4 T _ZN5boost10filesystem6detail14symlink_statusERKNS0_4pathEPNS_6system10error_codeE 000019c0 T _ZN5boost10filesystem6detail6statusERKNS0_4pathEPNS_6system10error_codeE 00001b54 T _ZNK5boost10filesystem15directory_entry12m_get_statusEPNS_6system10error_codeE 00001e98 T _ZNK5boost10filesystem15directory_entry20m_get_symlink_statusEPNS_6system10error_codeE ================================= my project-config.jam: # Boost.Build Configuration # Automatically generated by bootstrap.sh import option ; import feature ; # Compiler configuration. This definition will be used unless # you already have defined some toolsets in your user-config.jam # file. #if ! gcc in [ feature.values <toolset> ] #{ using gcc : armhf : arm-unknown-linux-gnueabi-g++ : <compileflags>-fexpensive-optimizations <compileflags>-O3 <compileflags>-march=armv7-a <compileflags>-mtune=cortex-a9 <compileflags>-mfpu=neon <compileflags>-mfloat-abi=hard <compileflags>-ftree-vectorize <compileflags>-ffast-math <compileflags>-funsafe-math-optimizations <compileflags>-pipe <compileflags>-fwhole-program <compileflags>-fpermissive <compileflags>-fPIC ; #} project : default-build <toolset>gcc ; # Python configuration using python : 2.7 : ; # List of --with-<library> and --without-<library> # options. If left empty, all libraries will be built. # Options specified on the command line completely # override this variable. libraries = ; # These settings are equivivalent to corresponding command-line # options. option.set prefix : /usr/local ; option.set exec-prefix : /usr/local ; option.set libdir : /usr/local/lib ; option.set includedir : /usr/local/include ; # Stop on first error option.set keep-going : false ; ================================= I use this patch to fix the zlib problem in boost_1.55 cat no_zlib.diff Index: libs/iostreams/build/Jamfile.v2 --- libs/iostreams/build/Jamfile.v2 (revision 6521) +++ libs/iostreams/build/Jamfile.v2 (working copy) @@ -159,8 +159,6 @@ : $(sources) : <link>shared:<define>BOOST_IOSTREAMS_DYN_LINK=1 <define>BOOST_IOSTREAMS_USE_DEPRECATED - [ ac.check-library /zlib//zlib : <library>/zlib//zlib - <source>zlib.cpp <source>gzip.cpp ] : : <link>shared:<define>BOOST_IOSTREAMS_DYN_LINK=1 ; ================================= my b2 command: ./b2 link=static threading=multi --tool-set=gcc-armhf --without-python -sNO_COMPRESSION=1

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[Graph] Reserving graph memory (again)
by Sensei 01 Apr '15

01 Apr '15

Dear all, Reading all the documentation online about memory reservation in a graph, I am still wondering if it would be possible to reserve memory in advance. With a vecS container it would be quite an advantage to reserve memory, but let me be clear, I am not saying that I know the number of edges in advance, so CRS isn't an option. Until now I know of two ways to do this. The first is to add & remove an edge: add_edge(0, num_vertices(g) + list.size() - 1, g); remove_edge(0, num_vertices(g) + list.size() - 1, g); however, it won't work in my context since I could (as you see from the code) add edges to an existing graph, and I am getting weird results. I am sure this is due to my code, however, add/remove isn't really a neat solution. The second option is weird: g.m_vertices.resize(list.size() - 1); This could be used, but m_* members should, as far as I understand, be private or protected. Is there any other nice possibility? For instance, a static function in the traits that reserves memory? In case, why this cannot be done by BGL APIs? Thanks!

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[asio]
by georg＠schorsch-tech.de 31 Mar '15

31 Mar '15

Hi all, currently i try to understand boost asio a little better. Right now, i just had a very simple asio program and started 2 timers asyncronously. i expected the timer t to complete after the timer i. //-------<----------------- Current output: 10 s. 1 s. //-------<----------------- Expected output: 1 s. 10 s. //-------<----------------- Shouldn't complete the async_wait with 1 sec complete prior the 10 sec async_wait? I am on Windows 7 x64/ MSVC 2013(VS12) / Boost 1.57.0. Regards Georg //-------<----------------- #include <boost/asio.hpp> #include <boost/system/error_code.hpp> #include <iostream> void wait_handler(const boost::system::error_code &ec) { if (!ec) std::cout << "10 s." << std::endl; } void irq_handler(const boost::system::error_code &ec) { if (!ec) std::cout << "1 s." << std::endl; } int main() { boost::asio::io_service io_service; boost::asio::deadline_timer t(io_service, boost::posix_time::seconds(10)); boost::asio::deadline_timer i(io_service, boost::posix_time::seconds(1)); t.async_wait(&wait_handler); t.async_wait(&irq_handler); io_service.run(); } //-------<-----------------

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Serialization cumulatively.
by Tony Camuso 30 Mar '15

30 Mar '15

I'm trying to serialize the data from multiple passes of an app on various files. Each pass generates data that must be serialized. If I simply append each serialization, then deserialization will only occur for the first instance, since the number of records read by the deserialization will only be for the first instance. What I'm doing is deserializing on each new pass, deleting the original file, and then serializing everything again with the new information. If there were only a few files to process, this would not be a problem. However there are thousands of files. Additionally, on each new pass, I am checking to see if a certain type of record has already been saved. So, with every pass, I must look up in a deeper and deeper database. Currently, it's taking almost an hour to process about 3000 files, with an average of 55,000 lines per file. It is a huge amount of data. However, I'm looking for a way to reduce the length of time it takes to do this processing. Does anybody have a better idea than to cycle through the serialize-deserialize-lookup-serialize sequence for each file?

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gicatena
by gicatena 29 Mar '15

29 Mar '15

Wei zio!, http://dronepromocodes.com/rwyw/nbfqqnawiivmwaqogeijytr.dkroguozxdavjgpqlor… 3/29/2015 3:11:42 AM

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[gsoc15] Please help rank GSoC 2015 student projects
by Niall Douglas 27 Mar '15

27 Mar '15

Dear Boost Community, The Google Summer of Code 2015 proposals for Boost are in, and we would deeply appreciate the community's help in ranking the proposals according to merit before the 6th of April. To vote, the process is easy: 1. Go to this page https://www.google-melange.com/gsoc/homepage/google/gsoc2015 and click the "Log in" button under Mentors and Administrators. 2. Now click "Create Profile" on the same page. Note that even if you registered last year, you must register again in 2015. Fill in the form. Note that after submitting it drops you at "Edit Profile", which is confusing. 3. Click "My Dashboard", then "Connect with organisations". 4. Choose "Boost C++ Libraries". 5. In the message box, write this: "I am a member of the Boost community and the email(s) I normally post to boost mailing lists with is <email>" filling in the email address(es) you normally use to post to boost mailing lists. This lets us verify that you are indeed a long standing member of the Boost community. 6. Once we approve your request, you will get an email with the subject "Welcome as organisation member". You can now return to the Dashboard on the GSoC website where there will be a new item "Proposals". 7. Work your way through as many of the 33 proposals as you can. You can score them using the stars at the bottom of each proposal page, taking care to read any comments by the mentors and students if present. PLEASE try to rank some of the lowest scored proposals, every year we get a lot of people who only rank the top five and don't bother with the rest. Try to score on the priority basis of: (i) ability to write quality C++, using the programming competency test or samples of programming the student supplied. (ii) proposal quality and your best estimate of the student's understanding of how best to solve the problem at hand. Bear in mind a gifted programmer with a strong work ethic but poor English may appear to not understand the problem as well as native English speakers, this is why we have asked for examples of their programming competency. (iii) if the student came early to the mailing lists to ask for help writing the proposal (the mentors who helped them with their proposals have usually indicated this in the private comments). (iv) usefulness/appropriateness of the feature or work being proposed. Remember a good GSoC is more about getting promising new engineers into Boost and C++ than necessarily getting code to pass Boost peer review in a single summer. 8. Optional: If a proposal looks especially great to you and you feel able to mentor a student this year, please slide the "wish to mentor" button. Just because a proposal already has willing mentors does NOT mean you should not add yourself - if you can substitute for an existing mentor, that may mean we use that mentor for another proposal. As you know, Google Summer of Code is usually worth $42,000 - $48,000 to Boost each year, and a successful GSoC raises our visibility and reputation in the wider open source community. Our thanks to you in advance for taking the time to vote. Niall Douglas Boris Schäling --- Boost C++ Libraries Google Summer of Code 2015 admin https://svn.boost.org/trac/boost/wiki/SoC2015

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problems using boost::polygon::get_rectangles
by TomDrummond 27 Mar '15

27 Mar '15

Hello I'm trying to use the function get_rectangles to return a list of rectangles however I can' get the code to compile. code #include <boost/polygon/polygon.hpp> std::vector< boost::polygon::rectangle_data<int> > rects; typedef boost::polygon::polygon_90_with_holes_data<int> Polygon90; Polygon90 poly; typedef boost::polygon::polygon_traits<Polygon90>::point_type MyPoint; MyPoint pts[] = { boost::polygon::construct<MyPoint>(0, 0), boost::polygon::construct<MyPoint>(0, 10), boost::polygon::construct<MyPoint>(30, 10), boost::polygon::construct<MyPoint>(30, 20), boost::polygon::construct<MyPoint>(10, 20), boost::polygon::construct<MyPoint>(10, 0) }; boost::polygon::set_points(poly, pts, pts + 6); boost::polygon::get_rectangles(rects, poly ); which gives the error 1>c:\lib\boost\1.57.0\boost\polygon\detail/rectangle_formation.hpp(261): error C2784: 'boost::rational<IntType> boost::abs(const boost::rational<IntType> &)' : could not deduce template argument for 'const boost::rational<IntType> &' from 'int' 1> C:\lib\boost\1.57.0\boost/rational.hpp(104) : see declaration of 'boost::abs' 1> c:\lib\boost\1.57.0\boost\polygon\polygon_90_set_data.hpp(180) : see reference to function template instantiation 'void boost::polygon::form_rectangles<output_container,std::_Vector_iterator<std::_Vector_val<std::_Simple_types<std::pair<int,std::pair<int,int>>>>>,boost::polygon::rectangle_concept>(output_container &,iterator_type,iterator_type,boost::polygon::orientation_2d,rectangle_concept)' being compiled 1> with 1> [ 1> output_container=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> , iterator_type=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<std::pair<int,std::pair<int,int>>>>> 1> , rectangle_concept=boost::polygon::rectangle_concept 1> ] 1> c:\lib\boost\1.57.0\boost\polygon\polygon_90_set_concept.hpp(86) : see reference to function template instantiation 'void boost::polygon::polygon_90_set_data<int>::get_rectangles<output_container_type>(output_container &) const' being compiled 1> with 1> [ 1> output_container_type=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> , output_container=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> ] 1> c:\lib\boost\1.57.0\boost\polygon\polygon_90_set_concept.hpp(86) : see reference to function template instantiation 'void boost::polygon::polygon_90_set_data<int>::get_rectangles<output_container_type>(output_container &) const' being compiled 1> with 1> [ 1> output_container_type=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> , output_container=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> ] 1> TerrainDispatcher.cpp(185) : see reference to function template instantiation 'void boost::polygon::get_rectangles<std::vector<boost::polygon::rectangle_data<int>,std::allocator<_Ty>>,Polygon90>(output_container_type &,const polygon_set_type &)' being compiled 1> with 1> [ 1> _Ty=boost::polygon::rectangle_data<int> 1> , output_container_type=std::vector<boost::polygon::rectangle_data<int>,std::allocator<boost::polygon::rectangle_data<int>>> 1> , polygon_set_type=Polygon90 1> ] I'm quite new to both boost and templates so any help would be appreciated. -- View this message in context: http://boost.2283326.n4.nabble.com/problems-using-boost-polygon-get-rectang… Sent from the Boost - Users mailing list archive at Nabble.com.

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[geometry] Buffer multi-linestring with different distances
by Renato Silveira 26 Mar '15

26 Mar '15

Is it possible to buffer a multi-linestring where each linestring has his own distance to buffer? Something like this: http://docs.qgis.org/2.2/en/_images/variable_buffer.png Thank you in advance -- *Renato Silveira* Ph. D. Student Informatics Institute - UFRGS Porto Alegre - RS - Brazil http://www.inf.ufrgs.br/~rsilveira

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