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

[units] (controlled) implicit conversion
by alfC 05 May '10

05 May '10

Hi, I took much labour in defining an extra system of units (atomic units). It works very well and it also defines (optionaly) default conversion from atomic to SI units. The problem that I have now is that all the conversion has to be done explicitly. I understand that this way of doing thing is by design. But for some formulas I would like to allow implicit conversion, for example when adding energies in SI and energies in atomic units (I don't care which direction the conversion is done since I will transform to one of the two at the end of the formula). On top of that the Units Manual says: "Safety and the potential for unintended conversions leading to precision loss and hidden performance costs. Options are provided for forcing implicit conversions between specific units to be allowed. " The question is which are the "Options provided for forcing implicit conversion"? What follow is an example: What I want is some controlled implicit conversion (even better is this conversion are allowed inside a certain program scope). Note that line 4 doesn't work: quantity<si::energy> e1(3.*si::joules); quantity<atomic::energy> e2(4.*atomic::hartree); quantity<atomic::energy> e3(e1); //works e1 = e2; //doesn't work e1 = quantity<si::energy>(e2); //works cout<<e1<<'\n'<<e2<<'\n'<<e3<<endl; note that the third line works because somewhere I defined a conversion_factor plus a default_conversion between units in the different systems. And it works because the conversion is explicit. Now the fourth line doesn't work, it gives an error (see at end). comenting the third line compiles. I even tried defining a conversion for this particular units, but still doesn't work. BOOST_UNITS_DEFINE_CONVERSION_FACTOR( boost::units::atomic::energy, boost::units::si::energy, double, 4.359744e-18 ); BOOST_UNITS_DEFAULT_CONVERSION( boost::units::atomic::energy, boost::units::si::energy ); error caused by line 4: In file included from /usr/include/boost/units/io.hpp:28, from /home/alfc/prj/mag/Qbox//units/systems/ atomic.hpp:187, from eos.cpp:8: /usr/include/boost/units/quantity.hpp: In member function ‘boost::units::quantity<Unit, Y>& boost::units::quantity<Unit, Y>::operator=(const boost::units::quantity<Unit2, YY>&) [with Unit2 = boost::units::unit<boost::units::list<boost::units::dim<boost::units::length_base_dimension, boost::units::static_rational<2l, 1l> >, boost::units::list<boost::units::dim<boost::units::mass_base_dimension, boost::units::static_rational<1l, 1l> >, boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x00000000000000002l, 1l> >, boost::units::dimensionless_type> > >, boost::units::homogeneous_system<boost::units::list<boost::units::atomic::electron_mass_base_unit, boost::units::list<boost::units::atomic::elementary_charge_base_unit, boost::units::list<boost::units::atomic::reduced_planck_constant_base_unit, boost::units::list<boost::units::atomic::coulomb_force_constant_base_unit, boost::units::list<boost::units::atomic::boltzman_constant_base_unit, boost::units::dimensionless_type> > > > > >, void>, YY = double, Unit = boost::units::unit<boost::units::list<boost::units::dim<boost::units::length_base_dimension, boost::units::static_rational<2l, 1l> >, boost::units::list<boost::units::dim<boost::units::mass_base_dimension, boost::units::static_rational<1l, 1l> >, boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x00000000000000002l, 1l> >, boost::units::dimensionless_type> > >, boost::units::homogeneous_system<boost::units::list<boost::units::si::meter_base_unit, boost::units::list<boost::units::scaled_base_unit<boost::units::cgs::gram_base_unit, boost::units::scale<10l, boost::units::static_rational<3l, 1l> > >, boost::units::list<boost::units::si::second_base_unit, boost::units::list<boost::units::si::ampere_base_unit, boost::units::list<boost::units::si::kelvin_base_unit, boost::units::list<boost::units::si::mole_base_unit, boost::units::list<boost::units::si::candela_base_unit, boost::units::list<boost::units::angle::radian_base_unit, boost::units::list<boost::units::angle::steradian_base_unit, boost::units::dimensionless_type> > > > > > > > > >, void>, Y = double]’: eos.cpp:115: instantiated from here /usr/include/boost/units/quantity.hpp:234: error: invalid application of ‘sizeof’ to incomplete type ‘boost::STATIC_ASSERTION_FAILURE<false>’ /usr/include/boost/units/quantity.hpp:234: error: invalid application of ‘sizeof’ to incomplete type ‘boost::STATIC_ASSERTION_FAILURE<false>’ Thank you, Alfredo

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[Boost/Quickbook] Can't create HTML files
by Carlos Guimarães 05 May '10

05 May '10

Hi, I'm trying to build documentation using quickbook. However I can't generate a HTML file from quickbook. When I build it, it creates 3 files: quickbook.docbook, quickbook.xml and boostbook_catalog.xml. With it, how can I create my HTML files? *user-config.jam* #For Quickbook - Doxygen using xsltproc ; using boostbook : /usr/share/xml/docbook/stylesheet/nwalsh : /usr/share/xml/docbook/schema/dtd/4.2 ; using doxygen ; *Jamfile* project documentation ; using quickbook ; import boostbook : boostbook ; boostbook mk : src/quickbook.qbk ; Thanks

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Can BOOST libraries be integrated with c++/CLR .net?
by Joe Pagliarulo 05 May '10

05 May '10

Hi, my name is Joe and I am new to the Boost libraries. Here's my question: Can BOOST libraries be integrated with c++/CLR .net? Does is work with clr/.NET? Thanks, Joe Pagliarulo

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[MultiArray] subscript to index
by Sami 05 May '10

05 May '10

Hi All, Does MultiArray provide a convenient way to get an raw-index (*i.e. *offset to an element in raw-data) given a collection of indices?

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flyweight with fusion::map = error C3066
by Cote, Francois (SGBM) 04 May '10

04 May '10

Dear All, I'm trying to create a composite structure of flyweight inspired by the example boost_1_41_0\libs\flyweight\example\composite.cpp. However, I need the leaf of my composite pattern to be a boost::fusion::map type. I'm getting the following error: \boost\variant\variant.hpp(825) : error C3066: there are multiple ways that an object of this type can be called with these arguments Is there any fundamental reason why the following code generate this error? The code compile when the leaf is a "struct" type rather than boost::fusion::map type. Regards Francois #include <boost/flyweight.hpp> #include <boost/functional/hash.hpp> #include <boost/variant.hpp> #include <boost/variant/apply_visitor.hpp> #include <boost/variant/recursive_wrapper.hpp> #include <boost/fusion/sequence.hpp> #include <boost/fusion/container/map.hpp> #include <iostream> #include <string> #include <vector> using namespace boost::flyweights; using boost::fusion::pair; using boost::fusion::make_pair; using boost::fusion::at_key; // using boost::fusion::map namespace leaf_key { struct label; } typedef boost::fusion::map<pair<leaf_key::label,std::string>> leaf; struct portfolio; typedef boost::variant<leaf,boost::recursive_wrapper<portfolio>> portfolio_variant; typedef boost::flyweights::flyweight<portfolio_variant> portfolio_node; struct portfolio:std::vector<portfolio_node>{}; struct portfolio_hasher: boost::static_visitor<std::size_t> { std::size_t operator()(const leaf& f )const { boost::hash<std::string> h; // using boost::fusion::map std::string str = at_key<leaf_key::label>(f); // using struct //std::string str = f.label; return h(str); } std::size_t operator()(const boost::recursive_wrapper<portfolio>& pf_w)const { const portfolio& pf=pf_w.get(); std::size_t res=0; for(portfolio::const_iterator it=pf.begin(),it_end=pf.end();it!=it_end;++it) { const portfolio_variant* p=&it->get(); boost::hash_combine(res,p); } return res; } }; std::size_t hash_value(const portfolio_variant& node) { return boost::apply_visitor(portfolio_hasher(),node); } int main() { return 0; } Emails aren't always secure, and may be intercepted or changed after they've been sent. Santander Global Banking & Markets doesn't accept liability if this happens. If you think someone may have interfered with this email, please get in touch with the sender another way. This message doesn't create or change any contract. Santander Global Banking & Markets doesn't accept responsibility for damage caused by any viruses contained in this email or its attachments. Emails may be monitored. If you've received this email by mistake, please let the sender know at once that it's gone to the wrong person and then destroy it without copying, using, or telling anyone about its contents. Abbey National Treasury Services plc Reg. No. 2338548. Registered Office: 2 Triton Square, Regent's Place, London, NW1 3AN. Registered in England. Abbey National Treasury Services plc is authorised and regulated by the Financial Services Authority (FSA Registration Number 146003). Cater Allen International Limited. Reg No. 2572704. Registered Office: 2 Triton Square, Regent's Place, London, NW1 3AN. Registered in England. Cater Allen International Limited is authorised and regulated by the Financial Services Authority (FSA Registration Number 148467). Santander Global Banking & Markets is a brand name used by Abbey National Treasury Services plc and Cater Allen International Limited.

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[fusion] at_key + for_each
by Denis Taniguchi 04 May '10

04 May '10

Hi, I was trying to implement something equivalent to the following piece of code: template <class Field1, class Field2, ... , class FieldN, class Range, class Function> Function for_each(Range &r, Function f) { using namespace boost; using namespace boost::fusion; BOOST_FOREACH(typename range_value<Range>::type &v, r) { at_key<Field1>(v) = f(at_key<Field2>(v), at_key<Field3>(v), ... , at_key<FieldN>(v)); } return f; } Is there a simple way to do this using fusion's current functionalities? Regards, Denis

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[Serialization] fast binary objects in portable archive
by Stepan Hrbek 04 May '10

04 May '10

Hello, my goal is fast portable serialization when 95% of data is in large binary objects. 1) binary_archive is fast, but nonportable. 2) text_archive is portable, but ~50x slower. 3) portable_binary_archive looks like solution, but I'm not able to use it to serialize by pointer. Problem can be demonstrated in demo_portable_archive.cpp of boost 1.42 by changing "char c;" to "A* c;" and "c(std::rand())" to "c(0)". Errors from VS2008 linker look like error LNK2019: unresolved external symbol "public: static class boost::archive::detail::basic_serializer const * __cdecl boost::archive::detail::archive_serializer_map<class portable_binary_iarchive>::find(class boost::serialization::extended_type_info const &)" (?find@?$archive_serializer_map@Vportable_binary_iarchive@@@detail@archive@boost@@SAPBVbasic_serializer@234@ABVextended_type_info@serialization@4@@Z) referenced in function "public: static class boost::archive::detail::basic_pointer_iserializer const * __cdecl boost::archive::detail::load_pointer_type<class portable_binary_iarchive>::find(class boost::serialization::extended_type_info const &)" (?find@?$load_pointer_type@Vportable_binary_iarchive@@@detail@archive@boost@@SAPBVbasic_pointer_iserializer@234@ABVextended_type_info@serialization@4@@Z) demo_portable_archive.obj Any idea how to fix it? 4) Is it possible to override text_archive to process binary objects faster, without converting them to text? Stepan

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[asio] io_service
by Etienne Philip Pretorius 04 May '10

04 May '10

Hello List, Is there documentation so that I could try and create a socket like class for the linux system call of inotify to be used by io_service? Etienne

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[units] easier scaled units generation
by alfC 04 May '10

04 May '10

scaled units are a great feature of boost.units, however it seems complicated to (explicitly) create variables in such units. This is the way I found to create a variable that stores a quantity like GigaPascals: using boost::units; typedef make_scaled_unit<si::pressure, scale<10, static_rational< 9> > >::type gpa_unit; gpa_unit GPa; quantity<gpa_unit> p(1.*GPa); //or p(1.*si::giga*si::pascal); the question is, is there a simpler way of doing this? for example, just quantity<giga<si::pressure> > p = ...; //values are converted/stored in giga pascals. I could add some "metafunction": template<class Unit> giga{ typedef make_scaled_unit<Unit, scale<10, static_rational< 9> > >::type unit; }; and use it like quantity<giga<si::pressure>::unit> p; and even specialize for femto, atto, mega, kile, etc. I this already implemented in some other way? In this way if I had implemented an electronvolt unit I could have megaelectronvolt for free quantity<mega<electronvolt_unit>::unit> energy = ...; Thank you, Alfredo

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[ASIO] native back into local::stream_protocol
by Etienne Philip Pretorius 04 May '10

04 May '10

Hello List, I just need some guidance here. I have a parent process fork off a child and pass the int value to the child indicating what the native socket file descriptor it should use to receive communication from the parent process. I am just not able to get it placed back into a boost::asio::local::stream_protocol::socket object. Here is the code below, from the child process loaded via execlp: for(int i = 3; i < static_cast<unsigned char>(~0); i++) { if(i == boost::lexical_cast<int>(argv[0])) { continue; } close(i); } boost::asio::io_service io_service; boost::asio::local::stream_protocol::socket parent_(io_service); parent_.assign(boost::asio::local::stream_protocol, boost::lexical_cast<int>(argv[0])); Compiler error: g++ -c -g -MMD -MP -MF build/Debug/GNU-Linux-x86/main.o.d -o build/Debug/GNU-Linux-x86/main.o main.cpp main.cpp: In function ‘int main(int, char**)’: main.cpp:30: error: expected primary-expression before ‘,’ token Thank you, Etienne -- This message has been scanned for viruses and dangerous content by Pinpoint, and is believed to be clean.

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