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

Re: [Boost-users] boost::interprocess boost::interprocess xsi_shared_memory
by Daniel Neuberger 12 Jan '11

12 Jan '11

Is there a reason for not finishing the implementation of XSI (System V) shared memory? It seems like most of the work is already done. If there is no reason not to, I might be able to finish the implementation so that it can be included in the next release. I know that POSIX may be sufficient for some, but System V allows for much better control using SELinux since it lives in kernel space. FYI: This is in response to http://thread.gmane.org/gmane.comp.lib.boost.user/64537. Thoughts? Thanks. - Daniel

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[Iterator] advance and random_access_traversal iterators
by Anthony Foglia 11 Jan '11

11 Jan '11

What happened to the patch to add a boost::advance function designed to work with Boost.Iterator's concepts? Three years ago there was a thread pointing out the problem with std::advance not treating random access traversal iterators as random access (because of the reference type). Sebastian Redl posted a patch to add a boost::advance (and boost::distance) function. <http://lists.boost.org/Archives/boost/2007/09/127785.php> I don't see any proof of this patch ever being applied. … [View More]

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[DateTime] Daily Schedules
by John Rocha 07 Jan '11

07 Jan '11

I was looking at the DateTime library for a scheduling module in my application. I was very excited to see time periods (time_period) and its method contains(). I could set up a time_period for say 8:00-17:00, and then when something happened I could create a ptime and see if the time_period contains my ptime. (i.e. did my action happen between 8:00 and 17:00.) However, I realized that a time period is much more specific than I want. A time_period is tied to a specific date, i.e. 8:00-17:… [View More]

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[Accumulators] Retract samples
by Alex Hagen-Zanker 06 Jan '11

06 Jan '11

Dear all, I am considering using Boost Accumulators for a moving window calculation. When a window would step from left to right, it should add the sample on the right side of the window and retract the sample on the left side on each step. For weighted accumulators, it might be possible to use negative weights. But, since the accumulators do not appear to be intended for this use, there may be implementation details that invalidate the use of negative weights. Is there a recommended … [View More]

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Problems in CodeGear
by jose perez 06 Jan '11

06 Jan '11

Hello. I'm unable to compile boost in Embarcadero 2010 (CodeGear) version 0x621. My code is really simple: #include "boost/random/mersenne_twister.hpp" This produces this error: [BCC32 Error] mersenne_twister.hpp(63): E2299 Cannot generate template specialization from 'detail::disable_constructor<Engine,T>' in the line: BOOST_RANDOM_DETAIL_GENERATOR_CONSTRUCTOR(mersenne_twister, Generator, gen) { seed(gen); } I have preprocessed my .cpp in order to see if boost gets correctly … [View More]

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[property_tree] Parsing JSON
by Olivier Tournaire 05 Jan '11

05 Jan '11

Hi all, I am currently trying to parse a JSON file, but cannot figure how to achieve this task (see for instance http://ax.itunes.apple.com/WebObjects/MZStoreServices.woa/wa/wsSearch?term=… ). Here is a piece of code: #ifndef ITUNES_JSON_STRUCTURE_HPP #define ITUNES_JSON_STRUCTURE_HPP #include <boost/property_tree/ptree.hpp> #include <string> class itunes_json_structure { public: void load(const std::string &filename); boost::property_tree::ptree m_ptree; … [View More]

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Visualizer for boost::tuple
by Mohamed Bana 05 Jan '11

05 Jan '11

Hello, I can't seem to find a visualizer for boost::tuple, does anyone have one lying around somewhere? I'm using Visual Studio 2005, if that's of any help. I appreciate the help. —Mohamed

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[Proto] callable_context
by Hossein Haeri 04 Jan '11

04 Jan '11

Dear all, I am trying to use callable_contexts to evaluate expressions like: x >> f >> g >> h; where this would be equivalent to h(g(f(x))). I have derived my context from callable_context, and thought I have overloaded for relevant tags (terminal and shift_right). GCC 4.5.1 (MinGW32, WinXP, SP3) stops with an error message which is cryptic to my current level of knowledge about Proto. I guess that's because I haven't done the job correctely. For your reference, I have … [View More]included a copy of my program as well as the error GCC gives me in the P.S. section of this posting. Any ideas please? TIA, --Hossein P.S. <code> #include <iostream> #include <boost/proto/proto.hpp> namespace mpl = boost::mpl; namespace proto = boost::proto; using proto::_; using namespace std; struct EWGrandDad { int evaluate() const; }; typedef proto::terminal<double (*) (double)> FunctionType; template<typename> struct EmtExpr; struct EmtGrammar: proto::or_ < proto::terminal<EWGrandDad>, proto::shift_right<EmtGrammar, FunctionType> > {}; struct EmtDomain: proto::domain<proto::generator<EmtExpr>, EmtGrammar> {}; template<typename Expr> struct EmtExpr : proto::extends<Expr, EmtExpr<Expr>, EmtDomain> { typedef proto::extends<Expr, EmtExpr<Expr>, EmtDomain> base_type; EmtExpr(const Expr& e = Expr()): base_type(e) {} }; struct EWBase : EmtExpr<typename proto::terminal<EWGrandDad>::type> { typedef typename proto::terminal<EWGrandDad>::type expr_type; EWBase(): EmtExpr<expr_type>(expr_type::make(EWGrandDad())) {} }; struct EW1: EWBase { EW1(int n1, int n2): n1_(n1), n2_(n2) {} int evaluate() const {return n1_ * n2_;} int n1_, n2_; }; double times2(double d) {return d * 2;} double minus1(double d) {return d - 1;} struct EmtContext: proto::callable_context<const EmtContext> { typedef double result_type; result_type operator() (proto::tag::terminal, const EWGrandDad& ew) const { return ew.evaluate(); } template<typename Expr> result_type operator() (proto::tag::shift_right, const Expr& e, FunctionType f) const { return f(proto::eval(e, *this)); } }; int main() { EmtContext emtCtx; cout << "result = " << emtCtx(EW1(4, 5) >> &times2 >> &minus1); return 0; } </code> <error message> main.cpp: In function 'int main()': main.cpp:82:63: error: no match for call to '(EmtContext) (const boost::lazy_enable_if_c<true, boost::proto::generatorns_::generator<EmtExpr>::result<EmtDomain(boost::proto::exprns_::expr<boost::proto::tag::shift_right, boost::proto::argsns_::list2<const EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::shift_right, boost::proto::argsns_::list2<const EW1&, EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<double (* const&)(double)>, 0l> > >, 2l> >&, EmtExpr<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<double (* const&)(double)>, 0l> > >, 2l>)> >::type)' main.cpp:67:14: note: candidate is: EmtContext::result_type EmtContext::operator()(boost::proto::tag::terminal, const EWGrandDad&) const </error message> [View Less]

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Mingw64 Boost Threads Build
by Dustin T. Clifford 04 Jan '11

04 Jan '11

Good Afternoon, We have been using boost-threads for our native APIs and, thus far, Boost has been a godsend! We had a recent request to build a 64-bit version of this API. To accomplish this we have attempted to build using MinGW64. Unfortunately, I have had zero luck getting boost-threads to build. I can build the 32-bit address model without a problem but 64-bit continues to elude me. I first tried Boost 1.35.0 and have now moved on to 1.45.0. I believe that the environment is set up … [View More]

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[units] subtract_typeof_helper<> help!
by Terry Golubiewski 04 Jan '11

04 Jan '11

I'm trying to use boost::geometry and boost::units together. For some reason boost::geometry doesn't represent the difference of two points as vectors. So, I'm making my own Vector class and defining Vector = Point - Point. The sample program below doesn't compile because I need to tell the units library about the special properties of point subtraction (I think). terry #include <boost/geometry/geometry.hpp> #include <boost/units/systems/si.hpp> #include <boost/units/… [View More]

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