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ptree json parser is not bidirectionnal
by Sébastien Gallou 25 Mar '16

25 Mar '16

Hi all, I experience a strange behavior of parsing non-JSON data with JSON parser. Take this example : boost::property_tree::ptree m_tree; > // Non-JSON to ptree using JSON parserstd::istringstream is("1"); // Simple value, non-JSON > boost::property_tree::json_parser::read_json(is, m_tree); // ==> No exception ! > // ptree back to JSONstd::ostringstream buf; > boost::property_tree::json_parser::write_json(buf, m_tree, false); // ==> Exception > > Unserializing non-JSON value using JSON parser doesn't raise exception. If you try to serialize the resulted ptree, you now got an exception. Is this behavior normal ? In this case, is there an easy and light mean to check that input value is JSON formatted (Regex ?) ? Thanks for your help, S. Gallou

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How to add child tree into an existing tree.
by Anil Jangam 24 Mar '16

24 Mar '16

Hi, I have the following property tree. propset1 { prop1 2 prop2 5 prop3 60 prop4 7 } I am trying to add couple of child trees to this so that the resulting property tree would look like below. propset1 { prop1 2 prop2 5 prop3 60 prop4 5 childset1 { child1prop1 4 child1prop1 6 child1prop1 9 } childset2 { child2prop1 2 child2prop1 6 child2prop1 7 } } I wrote the following code. // Add General config pt::ptree propset1; propset1.put("propset1.prop1", 2); propset1.put("propset1.prop2", 5); propset1.put("propset1.prop3", 60); propset1.put("propset1.prop4", 7); // Add childset1 config pt::ptree childset1; childset1.add("child1prop1", 4); childset1.add("child1prop2", 6); childset1.add("child1prop3", 9); propset1.add_child("childset1", childset1); // Add childset2 config pt::ptree childset2; childset2.add("child2prop1", 2); childset2.add("child2prop2", 6); childset2.add("child2prop3", 7); propset1.add_child("childset2", childset2); However the above code is resulting into below property tree. propset1 { prop1 2 prop2 5 prop3 60 prop4 5 childset1 { child1prop1 4 child1prop1 6 child1prop1 9 } } propset1 { prop1 2 prop2 5 prop3 60 prop4 5 childset2 { child2prop1 2 child2prop1 6 child2prop1 7 } } Can someone please suggest what is correct use of API? /anil

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Selecting function overloads with boost::overload()
by Reza Jahanbakhshi 23 Mar '16

23 Mar '16

First a little bit of background. Recently I've been using boost.python and I noticed choosing a specific function overload is kind of messy when defining class interfaces or free functions. Consider the following functions and member functions: void fn(int i, float f); int fn(const std::string& str); float car::method(); void car::method(int i, double d); According to boost.python documentation we can add these function using either of following constructs: void (*fn1)(int, float) = fn; int (*fn2)(const std::string&) = fn; def("fn", fn1); def("fn", fn2); float (car::*method1)() = &car::method; void (car::*method2)(int, double) = &car::method; .def("method", method1) .def("method", method2) or to avoid those intermediate variables we can do it directly: def("fn", (void (*)(int, float))fn); def("fn", (int (*)(const std::string&))fn); .def("method", (float(car::*)())&car::method) .def("method", (void (car::*)(int, double))&car::method) Which in my opinion is not readable enough. So I wrote a small utility to make it a little bit more readable. For example: def("fn", overload<void(int, float)>(fn)); def("fn", overload<int(const std::string&)(fn)); .def("method", overload<float()>(&car::method)); .def("method", overload<void(int, double)>(&car::method)); Notice how I gave the desired signature to the overload function and it will choose that exact overload for me. It's not only limited to boost.python and we can use it wherever we need to select a specific overloaded function. For example: auto f = overload<void(int, float)>(fn); Of course it's just a syntactic sugar and you might not find it improving anything at all but in my case it helped my code readability somehow. Now my question. I pasted the whole thing here. As for non-member functions I could implement it relying only on C++11 variadic templates. But for member functions I couldn't find a way to do it without boost.preprocess and using only C++11 variadic template. Here is the full code tested with GCC 5.3.1 (std=C++11), Clang 3.7.0 (std=C++11) and MSVC2015 #include <type_traits> #include <boost/mpl/vector.hpp> #include <boost/preprocessor/arithmetic/inc.hpp> #include <boost/preprocessor/punctuation/comma_if.hpp> #include <boost/preprocessor/repetition.hpp> namespace boost { namespace detail { template <typename SignatureType> struct fn_signature; template <typename ResultType, typename... ArgType> struct fn_signature<ResultType(ArgType...)> { using result_type = ResultType; using arg_type = boost::mpl::vector<ArgType...>; static const std::size_t arg_count = sizeof...(ArgType); using type = ResultType(*)(ArgType...); }; template <typename ClassType, typename SignatureType> struct memfn_signature; template <typename ClassType, typename ResultType, typename... ArgType> struct memfn_signature<ClassType, ResultType(ArgType...)> { using type = ResultType(ClassType::*)(ArgType...); }; } // namespace detail template <typename SignatureType> typename detail::fn_signature<SignatureType>::type overload(typename detail::fn_signature<SignatureType>::type fn) { return fn; } #define BOOST_OVERLOAD_MAX_ARGS_COUNT 5 #define BOOST_OVERLOAD_PP_METHOD_OVERLOAD_ARGS(Z, N, C) BOOST_PP_COMMA_IF(N) typename std::enable_if<detail::fn_signature<SignatureType>::arg_count == C, typename boost::mpl::at_c<typename detail::fn_signature<SignatureType>::arg_type, N>::type>::type #define BOOST_OVERLOAD_PP_METHOD_OVERLOAD_IMPL(Z, N, _) \ template <typename SignatureType, typename ClassType> \ typename detail::memfn_signature<ClassType, SignatureType>::type overload(typename detail::fn_signature<SignatureType>::result_type(ClassType::*memfn)(BOOST_PP_REPEAT(N, BOOST_OVERLOAD_PP_METHOD_OVERLOAD_ARGS, N))) \ { \ return memfn; \ } BOOST_PP_REPEAT(BOOST_PP_INC(BOOST_OVERLOAD_MAX_ARGS_COUNT), BOOST_OVERLOAD_PP_METHOD_OVERLOAD_IMPL, _) #undef BOOST_OVERLOAD_PP_METHOD_OVERLOAD_IMPL #undef BOOST_OVERLOAD_PP_METHOD_OVERLOAD_ARGS #undef BOOST_OVERLOAD_MAX_ARGS_COUNT } // namespace boost The problem is I cannot find a way to force the overload resolution to pick the specific overload and also automatically deduce the ClassType template parameter at the same time. If the language let me to alias a variadic template parameter then it would be possible to do it. For example I could do this: template <typename ClassType, typename ResultType, typename... ArgType> struct memfn_signature<ClassType, ResultType(ArgType...)> { using type = ResultType(ClassType::*)(ArgType...); using result_type = ResultType; *using arg_type = ArgType...;* }; template <typename SignatureType, typename ClassType> typename detail::memfn_signature<ClassType, SignatureType>::type overload(typename detail::memfn_signature<SignatureType>::result_type (ClassType::*memfn)(typename detail::memfn_signature<SignatureType>::arg_type)) { return memfn; } Right now my preprocess implementation works with no problem but It's not a clean implementation. So is there any other way that I can do this. I appreciate your help.

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Boost.Serialization how to use serialize without nvp
by gast128 23 Mar '16

23 Mar '16

Hello all, we basically have a setup like this: #ifdef _DEBUG template <typename T> struct Wrapper { T m_value; }; #define HANDLE(T) Wrapper<T> #else #define HANDLE(T) T #endif We want archives the same for debug and release. So I tried a couple of things: * use primitive_type: This doesn't work if the type T is a string. Basically it doesn't come in the 'load(std::wstring &ws)' anymore, since it now routes to operator<< and then all kinds of nasty thing happens for xml archives. * overload serialize. This is also a failure, since it expects somehow a nvp, which I tried to circumvent since then there is a difference between archives in debug or release. Using 'is_wrapper' doesn't help either template <class Archive, typename T> void serialize(Archive& ar, Wrapper<T>& r, const unsigned int) { ar & r.m_value; // static assert in basic_xml_iarchive::load_override } somehow I must specify raw storage in the serialize function, but load_override and its siblings are all protected. Anyone?

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Sean Parent to Keynote C++Now 2016
by Jon Kalb 22 Mar '16

22 Mar '16

Boost Users, C++Now is announcing that the keynote speaker for our tenth conference will be the keynote that started us off, Sean Parent. http://cppnow.org/2016-conference/announcements/2016/03/22/keynote-announced .html Jon

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windows 10 support in boost
by Hinrich Aue 22 Mar '16

22 Mar '16

Hello, can anybody tell me if boost supports windows 10? And from which version? Hinrich Hinrich Aue Sr. Software Engineer Kofax Development GmbH Wentzinger Strasse 19 79106 Freiburg Germany Tel: +49 761 452 69 57234 Fax: +49 761 452 69 58734 Hinrich.Aue(a)kofax.com blog<http://www.kofax.com/blog/> | twitter<https://twitter.com/Kofax> | linkedin<https://www.linkedin.com/company/kofax> | facebook<https://www.facebook.com/kofax.inc> | talent network<http://www.jobs.net/jobs/Kofax-Inc/join> ________________________________ This communication is only for the use of the intended recipient. It may contain confidential or proprietary information. If you are not the intended recipient or have received this communication in error, please notify the sender via phone and destroy this communication immediately. Kofax Development GmbH Sitz der Gesellschaft: Freiburg i. Brg. Registergericht: Amtsgericht Freiburg i.Br. Registernummer: HRB 7007 Gesch?ftsf?hrer: Bradford Weller, Christian Hefner, Daniel Geiger

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Re: [Boost-users] [boost] Boost 1.61.0 Beta 1 Release Candidate 1
by Daniel James 21 Mar '16

21 Mar '16

On 19 March 2016 at 19:38, Vladimir Prus <vladimir.prus(a)gmail.com> wrote: > > Release candidates for 1.61.0 beta 1 are now available: > > http://boost.cowic.de/rc/boost_1_61_0_b1_rc1.zip > http://boost.cowic.de/rc/boost_1_61_0_b1_rc1.tar.bz2 > http://boost.cowic.de/rc/boost_1_61_0_b1_rc1.tar.gz > http://boost.cowic.de/rc/boost_1_61_0_b1_rc1.7z I've put the documentation on the website. It's linked from the release notes: http://www.boost.org/users/history/version_1_61_0.html

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Confused by boost graph descriptor invalidation
by Paolo Bolzoni 21 Mar '16

21 Mar '16

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Dear list, I have a adjacency_list with OutEdgeList and VertexList as vecS and I do need to split edges. To split an edge is to remove it, replace with two edges with a new vertex in the middle. Since I am changing the graph I want to be sure how the invalidation works and so I read the page in[1], but I am confused by the table "Summary of Descriptor and Iterator Invalidation." The text states the table summarizes which operations cause descriptors and iterators to become invalid, said so what does "OK" means? My feeling is that iterators never become invalid, is that the case? And what "EL=vecS && Directed=directedS" means? It means that you are _fine_ only if you are working with a adjcency_list with OutEdgeList as vecS and Directed=directedS or the opposite (i.e., if you are using such adjcency_list then all iterators become invalid) Yours faithfully, Paolo [1] http://www.boost.org/doc/libs/release/libs/graph/doc/adjacency_list.html -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJW78v4AAoJENxW6b8QprD6Aq4H/jXK9kfFy65yZzzzySsFteS6 V9PFvCyrjzgrbGojMZok3Xxz2fJBvfvomqnzEgDuFy7I1P73dkyL3gbwRoPINQpN Qu/0zqskpWf6gJjnu0/3QtSDRBQ1hvT/ZmfhfoUyh1CSQuxyH+/VQV5V4uaDxymQ /atbZWn8Ry1e4noHlS1l27FvEF+qsxOGaHsqBr1Of5KYvcdWmEqN2PJjqWF87Ev7 +sCY4/aD5rT0n+FLBa/Qk/opblbNYprjCmTgpWjKh4lnRmrHJAJNTQeKwZC+e8Hx SOqW2kAQMRW46/y+VcMnOOv+M5UOxqj0K+EgAWVLaoyAZTJzbSc2E9VQL3fB4AA= =xH7S -----END PGP SIGNATURE-----

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boost linker errors
by Mark 21 Mar '16

21 Mar '16

Hi I am trying to link to a boost library, program_options, using Visual Studio 2015 and I am getting 'lnk2019 unresolved external symbol’ errors. I have built the boost libraries using b2 and built the complete libraries for msvc. The libraries are 32 bit. I have configured visual studio to point at the correct location for both the headers and the libraries, I’ve confirmed this. I am statically linking against libboost_program_options-vc140-mt-sgd-1_60.lib, though I have tried all the other variants of this library, e.g. removed the mt, the gd and the s parts of the name, without effect. I have tried all the different calling convention options in properties, I am building with the /MTd option set, though I have tried others. i have searched the internet thoroughly and cannot find a replication of my problem. Using BOOST_LIB_DIAGNOSTIC confirms that the library is being linked, I see the message in the output window. The errors I am getting are: Severity Code Description Project File Line Suppression State Error LNK2019 unresolved external symbol "void __cdecl simulate(class nemo::Simulation *,unsigned int,unsigned int,class std::basic_ostream<char,struct std::char_traits<char> > &)" (?simulate@@YAXPAVSimulation@nemo@@IIAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@@Z) referenced in function _main NeMo_Test C:\Users\Development\Documents\Visual Studio 2015\Projects\NeMo_Test\NeMo_Test\main.obj 1 Error LNK2019 unresolved external symbol "long __cdecl benchmark(class nemo::Simulation *,unsigned int,unsigned int,class boost::program_options::variables_map &,unsigned int)" (?benchmark@@YAJPAVSimulation@nemo@@IIAAVvariables_map@program_options@boost@@I@Z) referenced in function _main NeMo_Test C:\Users\Development\Documents\Visual Studio 2015\Projects\NeMo_Test\NeMo_Test\main.obj 1 Error LNK2019 unresolved external symbol "class nemo::Configuration __cdecl configuration(class boost::program_options::variables_map &)" (?configuration@@YA?AVConfiguration@nemo@@AAVvariables_map@program_options@boost@@@Z) referenced in function _main NeMo_Test C:\Users\Development\Documents\Visual Studio 2015\Projects\NeMo_Test\NeMo_Test\main.obj 1 Error LNK2019 unresolved external symbol "class boost::program_options::variables_map __cdecl processOptions(int,char * * const,class boost::program_options::options_description const &)" (?processOptions@@YA?AVvariables_map@program_options@boost@@HQAPADABVoptions_description@23@@Z) referenced in function _main NeMo_Test C:\Users\Development\Documents\Visual Studio 2015\Projects\NeMo_Test\NeMo_Test\main.obj 1 Error LNK2019 unresolved external symbol "class boost::program_options::options_description __cdecl commonOptions(void)" (?commonOptions@@YA?AVoptions_description@program_options@boost@@XZ) referenced in function _main NeMo_Test C:\Users\Development\Documents\Visual Studio 2015\Projects\NeMo_Test\NeMo_Test\main.obj 1 Error LNK1120 5 unresolved externals NeMo_Test C:\Users\Development\Documents\Visual Studio 2015\Projects\NeMo_Test\Debug\NeMo_Test.exe 1 I would be very grateful if anyone could provide a clue as to what I am missing or have done wrong. Many thanks

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[Fit] formal review starts today
by Vicente J. Botet Escriba 21 Mar '16

21 Mar '16

Dear Boost community, sorry for the late anounce The formal review of Paul Fultz II's Fit library starts today, 2nd March and ends on 13th March. Fit is a header-only C++11/C++14 library that provides utilities for functions and function objects. Fit is: - Modern: Fit takes advantages of modern C++11/C++14 features. It support both `constexpr` initialization and `constexpr` evaluation of functions. It takes advantage of type deduction, varidiac templates, and perfect forwarding to provide a simple and modern interface. - Relevant: Fit provides utilities for functions and does not try to implement a functional language in C++. As such, Fit solves many problems relevant to C++ programmers, including initialization of function objects and lambdas, overloading with ordering, improved return type deduction, and much more. - Lightweight: Fit builds simple lightweight abstraction on top of function objects. It does not require subscribing to an entire framework. Just use the parts you need. Fit is divided into three components: * Function Adaptors and Decorators: These enhance functions with additional capability. * Functions: These return functions that achieve a specific purpose. * Utilities: These are general utilities that are useful when defining or using functions Fit has been tested on gcc 4.6-4.9, clang 3.4-3.7, and Visual Studio 2015. For more information see: Github:https://github.com/pfultz2/Fit/tree/boost Documentation:http://pfultz2.github.io/Fit/doc/html/ We encourage your participation in this review. At a minimum, kindly state: - Whether you believe the library should be accepted into Boost * Conditions for acceptance - Your name - Your knowledge of the problem domain. You are strongly encouraged to also provide additional information: - What is your evaluation of the library's: * Design * Implementation * Documentation * Tests * Usefulness - Did you attempt to use the library? If so: * Which compiler(s) * What was the experience? Any problems? - How much effort did you put into your evaluation of the review? More information about the review process can be found here:http://www.boost.org/community/reviews.html We await your feedback! Best regards, Vicente J. Botet Escriba

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