February 2015 - Boost-users

[Units] Heterogeneous unit for pressure per time
by Dina Goldshtein 28 Feb '15

28 Feb '15

Hi, I asked about this in StackOverflow<http://stackoverflow.com/questions/27519186/boost-heterogeneous-unit-bar-pe…> but didn't get any answers so I thought I'd try here as well. I need to create a unit which represents pressure per time, specifically Bar per Minute. I tried creating it in the same way as I created similar units before: typedef boost::units::derived_dimension<boost::units::length_base_dimension, -1, boost::units::mass_base_dimension, 1, boost::units::time_base_dimension, -3>::type pressure_roc_dimension; typedef boost::units::unit<pressure_roc_dimension, boost::units::make_system<boost::units::metric::bar_base_unit, boost::units::metric::minute_base_unit>::type> bar_per_minute_unit; BOOST_UNITS_STATIC_CONSTANT(BarPerMinute, bar_per_minute_unit::unit_type); typedef boost::units::quantity<bar_per_minute_unit, double> BarPerMinuteRoC; And then I try to use it: BarPerMinuteRoC bpm = 5.0 * BarPerMinute; But this line doesn't compile with quite a long error trail which I'm having a bit of trouble understanding fully. 1>c:\workspace\externals\boost_1_57_0\include\boost\units\detail\linear_algebra.hpp(197): error C2039: 'item' : is not a member of 'boost::units::dimensionless_type' 1> c:\workspace\externals\boost_1_57_0\include\boost\units\dimensionless_type.hpp(37) : see declaration of 'boost::units::dimensionless_type' 1> c:\workspace\externals\boost_1_57_0\include\boost\units\detail\linear_algebra.hpp(259) : see reference to class template instantiation 'boost::units::detail::determine_extra_equations_skip_zeros_impl<true,false>::apply<RowsBegin,1,1,3,Result>' being compiled 1> with 1> [ 1> RowsBegin=boost::units::list<boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::detail::make_zero_vector<0>::type>>,boost::units::detail::determine_extra_equations_skip_zeros_impl<false,true>::apply<boost::units::list<boost::units::list<boost::units::static_rational<-1,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::list<boost::units::static_rational<-2,1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>>,boost::units::dimensionless_type>,1,0,3,boost::units::list<boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::detail::make_zero_vector<0>::type>>>,boost::units::list<boost::units::list<boost::units::static_rational<-1,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::list<boost::units::static_rational<-2,1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>>,boost::units::dimensionless_type>>>::next_equations> 1> , Result=boost::units::list<boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::detail::make_zero_vector<0>::type>>>,boost::units::list<boost::units::list<boost::units::static_rational<-1,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::list<boost::units::static_rational<-2,1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>>,boost::units::dimensionless_type>> 1> ] 1> c:\workspace\externals\boost_1_57_0\include\boost\units\detail\linear_algebra.hpp(264) : see reference to class template instantiation 'boost::units::detail::determine_extra_equations<2,false>::apply<boost::units::list<boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::detail::make_zero_vector<0>::type>>,boost::units::detail::determine_extra_equations_skip_zeros_impl<false,true>::apply<boost::units::list<boost::units::list<boost::units::static_rational<-1,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::list<boost::units::static_rational<-2,1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>>,boost::units::dimensionless_type>,1,0,3,Result>::next_equations>,3,Result>' being compiled 1> with 1> [ 1> Result=boost::units::list<boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::detail::make_zero_vector<0>::type>>>,boost::units::list<boost::units::list<boost::units::static_rational<-1,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::list<boost::units::static_rational<-2,1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>>,boost::units::dimensionless_type>> 1> ] 1> c:\workspace\externals\boost_1_57_0\include\boost\units\detail\linear_algebra.hpp(538) : see reference to class template instantiation 'boost::units::detail::determine_extra_equations<3,false>::apply<Matrix,3,Matrix>' being compiled 1> with 1> [ 1> Matrix=boost::units::list<boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::detail::make_zero_vector<0>::type>>>,boost::units::list<boost::units::list<boost::units::static_rational<-1,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::list<boost::units::static_rational<-2,1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>>,boost::units::dimensionless_type>> 1> ] 1> c:\workspace\externals\boost_1_57_0\include\boost\units\detail\linear_algebra.hpp(828) : see reference to class template instantiation 'boost::units::detail::make_square_and_invert<boost::units::list<boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<0,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::detail::make_zero_vector<0>::type>>>,boost::units::list<boost::units::list<boost::units::static_rational<-1,1>,boost::units::list<boost::units::static_rational<1,1>,boost::units::list<boost::units::static_rational<-2,1>,boost::units::detail::expand_dimensions<0>::apply<boost::units::dimensionless_type,boost::units::dimensionless_type>::type>>>,boost::units::dimensionless_type>>>' being compiled 1> c:\workspace\externals\boost_1_57_0\include\boost\units\detail\linear_algebra.hpp(1032) : see reference to class template instantiation 'boost::units::detail::normalize_units<T>' being compiled 1> with 1> [ 1> T=boost::units::list<boost::units::scaled_base_unit<boost::units::si::second_base_unit,boost::units::scale<60,boost::units::static_rational<1,1>>>,boost::units::list<boost::units::metric::bar_base_unit,boost::units::dimensionless_type>> 1> ] 1> c:\workspace\externals\boost_1_57_0\include\boost\units\detail\linear_algebra.hpp(1051) : see reference to class template instantiation 'boost::units::detail::calculate_base_unit_exponents_impl<false>::apply<T,Dimensions>' being compiled 1> with 1> [ 1> T=boost::units::list<boost::units::scaled_base_unit<boost::units::si::second_base_unit,boost::units::scale<60,boost::units::static_rational<1,1>>>,boost::units::list<boost::units::metric::bar_base_unit,boost::units::dimensionless_type>> 1> , Dimensions=BSII::Units::pressure_roc_dimension 1> ] 1> c:\workspace\externals\boost_1_57_0\include\boost\units\heterogeneous_system.hpp(243) : see reference to class template instantiation 'boost::units::detail::calculate_base_unit_exponents<boost::units::list<boost::units::scaled_base_unit<boost::units::si::second_base_unit,boost::units::scale<60,boost::units::static_rational<1,1>>>,boost::units::list<T,boost::units::dimensionless_type>>,Dimensions>' being compiled 1> with 1> [ 1> T=boost::units::metric::bar_base_unit 1> , Dimensions=BSII::Units::pressure_roc_dimension 1> ] 1> c:\workspace\externals\boost_1_57_0\include\boost\units\unit.hpp(92) : see reference to class template instantiation 'boost::units::detail::make_heterogeneous_system<Dim,System>' being compiled 1> with 1> [ 1> Dim=BSII::Units::pressure_roc_dimension 1> , System=boost::units::homogeneous_system<boost::units::list<boost::units::scaled_base_unit<boost::units::si::second_base_unit,boost::units::scale<60,boost::units::static_rational<1,1>>>,boost::units::list<boost::units::metric::bar_base_unit,boost::units::dimensionless_type>>> 1> ] 1> c:\workspace\externals\boost_1_57_0\include\boost\units\unit.hpp(99) : see reference to class template instantiation 'boost::units::reduce_unit<S1>' being compiled 1> with 1> [ 1> S1=BSII::Units::bar_per_minute_unit 1> ] 1> c:\workspace\foundations\sw_foundations\bsii_common\test\src\units\units_pressure_test.cpp(97) : see reference to class template instantiation 'boost::units::is_implicitly_convertible<BSII::Units::bar_per_minute_unit,Unit>' being compiled 1> with 1> [ 1> Unit=BSII::Units::bar_per_minute_unit 1> ] According to the Boost documentation a homogeneous system can only be composed of linearly independent base units. In my case, I'm trying to mix bars (which in turn "contain" seconds as the time element) with minutes. This sounds problematic to me. But on the other hand, since I don't include mass and length base units in my system it seems to me that the base is independent after all. In any case, I searched online for an example of creating such a heterogeneous unit but didn't find anything comprehensible. Also, I read in the Boost documentation that a heterogeneous unit doesn't preserve information about how it was created. Does this mean I won't be able to, for instance, multiply BarPerMinuteRoC by Minute and get Bar back? Thanks a lot! Dina This message (including any attachments) is intended only for the use of the individual or entity to which it is addressed and may contain materials protected by copyright or information that is non-public, proprietary, privileged, confidential, and exempt from disclosure under applicable law or agreement. If you are not the intended recipient, you are hereby notified that any review use, dissemination, distribution, or duplication of this communication is strictly prohibited. If you are not the intended recipient, please contact the sender immediately by reply email and destroy all copies of the original. Thank you.

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[Preprocessor] Compile error after change from Boost 1.55 to 1.57
by Franz Alt 27 Feb '15

27 Feb '15

Hi, I've written some preprocessor directives to generate functions for a class. With Boost 1.55 everything works fine with gcc and clang. When I try to change to Boost 1.57 I've got some strange compile errors. I'm happy if someone could help. Thanks Franz gcc 4.9.1 failed with error: test.cpp:33:1: error: macro "BOOST_PP_SEQ_ELEM_III" requires 2 arguments, but only 1 given ) ^ test.cpp:33:1: error: macro "BOOST_PP_VARIADIC_ELEM_2" requires 4 arguments, but only 2 given test.cpp:60:1: error: macro "BOOST_PP_SEQ_ELEM_III" requires 2 arguments, but only 1 given MY_FUNCTION_BEGIN((b)) ^ test.cpp:60:1: error: macro "BOOST_PP_VARIADIC_ELEM_2" requires 4 arguments, but only 2 give clang 3.5.0 failed with error: test.cpp:30:3: error: too few arguments provided to function-like macro invocation MY_FUNCTIONS( \ ^ test.cpp:25:25: note: expanded from macro 'MY_FUNCTIONS' BOOST_PP_SEQ_FOR_EACH(FUNCTION_DECL, _, seq) ^ ..../boost.1_57_0/boost/preprocessor/seq/for_each.hpp:26:67: note: expanded from macro 'BOOST_PP_SEQ_FOR_EACH' # define BOOST_PP_SEQ_FOR_EACH(macro, data, seq) BOOST_PP_FOR((macro, data, seq (nil)), BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O, BOOST_PP_SEQ_FOR_EACH_M) ^ ..../boost.1_57_0/boost/preprocessor/repetition/detail/for.hpp:22:78: note: expanded from macro 'BOOST_PP_FOR_1' # define BOOST_PP_FOR_1(s, p, o, m) BOOST_PP_FOR_1_C(BOOST_PP_BOOL(p(2, s)), s, p, o, m) ^ note: (skipping 18 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all) packages/boost/boost_i4/boost/preprocessor/seq/elem.hpp:22:39: note: expanded from macro 'BOOST_PP_SEQ_ELEM' # define BOOST_PP_SEQ_ELEM(i, seq) BOOST_PP_SEQ_ELEM_I(i, seq) ^ packages/boost/boost_i4/boost/preprocessor/seq/elem.hpp:41:45: note: expanded from macro 'BOOST_PP_SEQ_ELEM_I' # define BOOST_PP_SEQ_ELEM_I(i, seq) BOOST_PP_SEQ_ELEM_II(BOOST_PP_SEQ_ELEM_ ## i seq) ^ packages/boost/boost_i4/boost/preprocessor/seq/elem.hpp:43:62: note: expanded from macro 'BOOST_PP_SEQ_ELEM_II' # define BOOST_PP_SEQ_ELEM_II(im) BOOST_PP_SEQ_ELEM_III(im) ^ packages/boost/boost_i4/boost/preprocessor/seq/elem.hpp:44:13: note: macro 'BOOST_PP_SEQ_ELEM_III' defined here # define BOOST_PP_SEQ_ELEM_III(x, _) x The program is: #include <iostream> #ifndef BOOST_PP_VARIADICS #define BOOST_PP_VARIADICS #endif #include <boost/preprocessor.hpp> #define ADD_CONST_REF(op, data, elem) elem const & #define FUNCTION_DECL(r, data, tup) \ double BOOST_PP_TUPLE_ELEM(0, tup) \ BOOST_PP_IF(BOOST_PP_LIST_IS_NIL(BOOST_PP_TUPLE_TO_LIST(BOOST_PP_TUPLE_ELEM(1, tup))), \ (), \ BOOST_PP_SEQ_TO_TUPLE( \ BOOST_PP_SEQ_TRANSFORM( \ ADD_CONST_REF, \ _, \ BOOST_PP_TUPLE_TO_SEQ(BOOST_PP_LIST_TO_TUPLE(BOOST_PP_TUPLE_TO_LIST(BOOST_PP_TUPLE_ELEM(1, tup)))) \ ) \ ) \ ) \ const; #define MY_FUNCTIONS(seq) \ BOOST_PP_SEQ_FOR_EACH(FUNCTION_DECL, _, seq) class Foo { public: MY_FUNCTIONS( \ ((a, (int))) \ ((b) ) \ ) }; #define ADD_ARG(op, data, elem) elem const & BOOST_PP_CAT(a_, elem) #define MY_FUNCTION_BEGIN(tup) \ double Foo::BOOST_PP_TUPLE_ELEM(0, tup) \ BOOST_PP_IF(BOOST_PP_LIST_IS_NIL(BOOST_PP_TUPLE_TO_LIST(BOOST_PP_TUPLE_ELEM(1, tup))), \ (), \ BOOST_PP_SEQ_TO_TUPLE( \ BOOST_PP_SEQ_TRANSFORM( \ ADD_ARG, \ _, \ BOOST_PP_TUPLE_TO_SEQ(BOOST_PP_LIST_TO_TUPLE(BOOST_PP_TUPLE_TO_LIST(BOOST_PP_TUPLE_ELEM(1, tup)))) \ ) \ ) \ ) const \ { #define MY_FUNCTION_END() } MY_FUNCTION_BEGIN((a, (int))) { std::cout << "Foo::a(" << a_int << ")\n"; } MY_FUNCTION_END() MY_FUNCTION_BEGIN((b)) { std::cout << "Foo::b()\n"; } MY_FUNCTION_END() int main() { Foo f; f.a(42); f.b(); return 0; }

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VMD library accepted
by Steven Watanabe 27 Feb '15

27 Feb '15

AMDG The VMD library submitted by Edward Diener is ACCEPTED into Boost. I apologize for the long delay for this announcement. Thanks to everyone who participated in the formal review * Nial Douglass * Bjorn Reese * Rodrigo Madera * Zhou Zhenghui * Matt Calabrese * Paul Mensonides Reviews for the library were generally positive. The library was considered to be a useful set of tools for macro programmers. Paul expressed concern about the way the the library handles v-sequences and v-identifiers. After some discussion, Edward has agreed that the interface could be significantly improved. Work Items: * Add examples and improved motivation in the documentation * Update the v-identifier/v-sequence interface based on Paul's comments * Fix inaccurate statements about Boost.Preprocessor per Paul In Christ, Steven Watanabe

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[Regex] Cannot build Regex without ICU
by Rob Desbois 26 Feb '15

26 Feb '15

I want to build the Boost libs without ICU support in Regex, but have been unable to prevent it from being linked in. I've run the following commands on a freshly extracted distribution of 1.57: ./bootstrap.sh --without-icu --prefix=/home/rob/workspace/deps/boost/1.57.0/linux/x64/ ./b2 install The bootstrap stage output includes this, which seems to indicate it's behaving correctly: Unicode/ICU support for Boost.Regex?... disabled. The resulting project-config.jam makes no mention of ICU. The build log includes: - has_icu builds : yes - icu : yes The shared library dependencies for the resulting libboost_regex.so.1.57.0 then include: libicuuc.so.50 => /lib64/libicuuc.so.50 (0x00007f74e5e3b000) libicui18n.so.50 => /lib64/libicui18n.so.50 (0x00007f74e5a3b000) libicudata.so.50 => /lib64/libicudata.so.50 (0x00007f74e4467000) I know the docs for Boost.Regex specify the bootstrap argument as --disable-icu, however this is rejected as invalid, unlike the argument I provide. Have I messed up somewhere or is this a bug? TIA -- rob -- Rob Desbois http://theotherbranch.wordpress.com/

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Re: [Boost-users] [ASIO] io_service::service::shutdown_service
by chmhou＠sina.com 25 Feb '15

25 Feb '15

>Hi, >Let us consider following execution sequence: >1. "io_service" destructor calls "io_service::service::shutdown_service"; >2. documentation of "io_service::service::shutdown_service" says that it >should destroy all user defined handler objects. >Is it true that user defined handler objects may access to (e.g. post a >handler) that "io_service" being destroyed and therefore has not exist >already? >Could You please also clarify me what does "user defined handler object" >really mean? >Thanks, >Andrew. Hi, Andrew For your 2nd question "user defined handler object", I supposed that the parameter for the io_service::post() which is kinda "user defined handler object". 1st, it could be a handler like "bind(&fun, this, _1, _2)". Martin

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Why does read_xml call fail if my property tree contains char16_t?
by ashish g 24 Feb '15

24 Feb '15

Hi I have a property tree which has strings of char16_t as both key and value datatypes. When I try to call read_xml() to load an xml file into this tree it fails. The same code however works with wchar_t. Seems like its failing on parse_bom() function. The code and error message can be seen here: http://coliru.stacked-crooked.com/a/3f922b43838fd7e8 Any tips on how to fix this issue. -- *Ashish Gudla*

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[fusion] Why is the std::tuple adapter undocumented?
by Rob Desbois 24 Feb '15

24 Feb '15

What it says on the tin really: Why is boost/fusion/adapted/std_tuple.hpp not documented at all? I'd like to use it but if it's undocumented because it's considered experimental then I'll use fusion's vector instead... TIA -- rob -- Rob Desbois http://theotherbranch.wordpress.com/

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Re: [Boost-users] Performance optimization in Boost using std::vector<>
by chmhou＠sina.com 24 Feb '15

24 Feb '15

Hi I got it, it supposed that I made a mistake on the duration. I will follow this question. Martin

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Re: [Boost-users] Performance optimization in Boost using std::vector<>
by chmhou＠sina.com 23 Feb '15

23 Feb '15

>Hi, >not sure if the OP needs std::vector but... I'd recommend >boost::container::vector which has a dedicated constructor [1] and >resize() [2] method tagged with default_init_t argument, both of which >default initialize the values in the vector. For primitives it basically >means it leaves them uninitialized, hence there's no overhead when the >vector is to be filled with real data soon. >WBR, >Adam Romanek Hi Adam As following your point, the benefit of boost::container::vector supported the "default_init_t" method so that it 's quite convince and safety comparing with std::vector<> is that right ? are there additional advantages ? Hi Ilja You said "Boost::mpi version is always at least 10 times slower. " make me confused, I guess it's should be a typo, isn't ? Martin

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Signals2 benchmark
by Joren Heit 22 Feb '15

22 Feb '15

Hi all, New to this list, so I hope I'm at the right place, and not asking too much of you guys. Please inform me if either of those is true! ;-) I have been working on a little toy project to implement a template-based Signal/Slot library and now that I have a usable end-product, I want to test it against boost::signals2 to get an idea of how well it performs. Therefore my first question is whether boost::signals2 is generally considered a high performance library. Second, I'm a little reluctant to build a benchmark suite myself, because I want to be fair to both myself and the other party. I don't know the signals2 library at all, let alone what its virtues and shortcomings are. Some tips on what to test exactly would therefore be great, although I'm afraid this request might qualify for "asking too much". Initial tests show that my own library can be up to 10 times faster than the boost-implementation, which makes me even more suspicious that I might not be testing the right things (but at the same time prematurely proud). Thanks in advance and cheers! Joren

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