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[BGL] vis passed by value to depth_first_visit
by Shaun Jackman 20 Apr '11

20 Apr '11

Hi, I recently learned the hard way that the visitor parameter, vis, is passed by value to depth_first_visit, but passed by reference to detail::depth_first_visit_impl. I was writing a function that implemented depth_first_search, but starts each of the visits at vertices with indegree == 0. If my depth_first_search replacement calls boost::depth_first_visit, each call to depth_first_visit makes a copy of the output iterator, which doesn't work for an output iterator with any state (such as a pointer). Calling an internal boost function like detail::depth_first_visit_impl doesn't seem like a good plan. How should I solve this? My short-term work around is to use an output iterator that does not have any state, such as a back_inserter. Cheers, Shaun

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error C2825: 'F': must be a class or namespace when followed by '::'
by simone pilozzi 20 Apr '11

20 Apr '11

Dear Users, I am using a pointer to a function member with the std::transform alorithm. The class is a QuantLib class called DayCounter and the method is called yearFraction and takes in two mandatory dates and two optionals to return the corresponding year fraction. *yearFraction ( QuantLib::Date t1,QuantLib::Date t2,QuantLib::Date t3 = Date(),QuantLib::Date t4=Date())* Now I tried to fill a vector called yearfracs in this way boost::shared_ptr<QuantLib::DayCounter> dc( new QuantLib::ActualActual); QuantLib::Date t = todaysDate() std::vector<QuantLib::Time> yearfracs; std::transform(subsample.begin(),subsample.end(), yearfracs.begin(),boost::bind(&QuantLib::ActualActual::yearFraction,&dc,t,_2)) subsample is the originary vector of dates. The compiler reported the following error error C2825: 'F': must be a class or namespace when followed by '::' What is the correct syntax for doing this? Thanks in advance Simone

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A problem with using boost::regex
by Michael Lindner 20 Apr '11

20 Apr '11

I have been a boost users for years, but this is the first time I've come across a problem with using it. I'm posting this in the hopes that one of you will say "oh yeah you did 'X' wrong", because I have been beating my head against the wall with this for some time. Thanks for taking a look. -- Michael Lindner I have the following program: #include "boost/regex.hpp" #include <string> int main(int argc, char** argv) { std::string re("[123]abc"); boost::regex reg(re); return 0; } It compiles and runs just fine on my Mac and Linux machines. On Windows, however, it compiles fine, and runs fine compiled under the "Debug" configuration. When I change that to "Release" however, it crashes with the following stack trace: msvcr90.dll!7858cc9d() msvcr90.dll!7858ccb5() dme.exe!boost::re_detail::w32_ transform() + 0xd5 bytes C++ dme.exe!boost::re_detail::w32_regex_traits_implementation<char>::transform() + 0x21 bytes C++ dme.exe!boost::re_detail::find_sort_syntax<boost::re_detail::w32_regex_traits_implementation<char>,char>() + 0x64 bytes C++ dme.exe!boost::re_detail::w32_regex_traits_implementation<char>::w32_regex_traits_implementation<char>() + 0x399 bytes C++ dme.exe!boost::object_cache<unsigned int,boost::re_detail::w32_regex_traits_implementation<char> >::do_get() + 0x28f bytes C++ dme.exe!boost::object_cache<unsigned int,boost::re_detail::w32_regex_traits_implementation<char> >::get() + 0x69 bytes C++ dme.exe!boost::re_detail::create_w32_regex_traits<char>() + 0x1b bytes C++ dme.exe!boost::re_detail::regex_data<char,boost::regex_traits<char,boost::w32_regex_traits<char> > >::regex_data<char,boost::regex_traits<char,boost::w32_regex_traits<char> > >() + 0x5d bytes C++ dme.exe!boost::basic_regex<char,boost::regex_traits<char,boost::w32_regex_traits<char> > >::do_assign() + 0x5f bytes C++ > dme.exe!boost::basic_regex<char,boost::regex_traits<char,boost::w32_regex_traits<char> > >::assign(const char * p1=0x0012ff4c, const char * p2=0x0012ff54, unsigned int f=0) Line 380 C++ dme.exe!boost::basic_regex<char,boost::regex_traits<char,boost::w32_regex_traits<char> > >::assign<std::char_traits<char>,std::allocator<char> >(const std::basic_string<char,std::char_traits<char>,std::allocator<char> > & s="[123]abc", unsigned int f=0) Line 418 C++ dme.exe!boost::basic_regex<char,boost::regex_traits<char,boost::w32_regex_traits<char> > >::basic_regex<char,boost::regex_traits<char,boost::w32_regex_traits<char> > ><std::char_traits<char>,std::allocator<char> >(const std::basic_string<char,std::char_traits<char>,std::allocator<char> > & p="[123]abc", unsigned int f=0) Line 393 C++ dme.exe!main(int argc=1, char * * argv=0x00345628) Line 9 C++ I am using boost 1.46.0 Microsoft Visual Studio 2008 Version 9.0.30729.1 SP Microsoft .NET Framework Version 3.5 SP1

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Interval: checking for equality
by gast128 20 Apr '11

20 Apr '11

Hello all, I was (mis)using the interval library for time intervals. However the equality operator fails for a simple test: boost::numeric::interval<int> intv1(1, 3); boost::numeric::interval<int> intv2 = intv1; //throws bool b = (intv1 == intv2); probably i don't understand the whole idea about this interval arithmetic library then. Could somebody tell me what I do wrong?

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[phoenix] v3 extension mechanism for template functions
by alfC 20 Apr '11

20 Apr '11

Hi, In Phoenix2 I used to have the following code to add expressions of type pow<N>(... expr...) which where useful for expressions involving Boost.Units. Is it possible to do something similar with Phoenix3. The usage if macros in the tutorial examples obscures how to add template parameters to the phoenix expression. In Phoenix2 it was straight forward, but I can figure out how to do this in Phoenix3. // phoenix2 code: #include <boost/units/pow.hpp> namespace boost{ namespace phoenix{ template<long N> struct pow_eval{ template <typename Env, typename Arg_> struct result{ typedef typename boost::units::power_typeof_helper<typename boost::mpl::at_c<typename Env::args_type, 0>::type, boost::units::static_rational<N> >::type type; }; template <typename RT, typename Env, typename Arg_> static RT eval(Env const& env, Arg_ const& arg_){ return boost::units::pow<N>(arg_.eval(env)); } }; template<long N, typename Arg_> actor<composite<pow_eval<N>, boost::fusion::vector<Arg_ > > > pow(actor<Arg_> const& arg_){ return compose<pow_eval<N> >(arg_); } }} use as pow<3>(arg1)(l)

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Accumulators: what is the difference between features<> and stats<> ?
by Andrew A 20 Apr '11

20 Apr '11

Is there any difference for example, between accumulator_set< double, features< tag::mean > > acc; and accumulator_set< double, stats< tag::mean > > acc; features and stats seems to be synonyms?

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can't take const ref to tribool's indeterminate
by Phil Nash 19 Apr '11

19 Apr '11

Hi all, The following does not compile (GCC 4.2): #include <boost/logic/tribool.hpp> template<typename T> void byRef( const T& v ) { } // ... byRef( boost::indeterminate ); I realise that indeterminate is actually a function. If I write my own, equivalent, function I can substitute it here and it compiles, however. I can't see what is stopping it from working in indeterminate's case - but I suspect it is to do with some of the operator overloading going on. I couldn't pin it down, though. I can take it by value, of course. What am I missing? Before you ask - yes this is boiled down code. In my real situation I have generic code that doesn't even know about tribool, so I can't special-case it. And I'd rather get to the bottom of why it doesn't work for me - even if the end result is "you can't do that". Thanks and regards, [)o IhIL..

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To produce bjam, put Boost Version 1.46.1 in a deep folder (at least 4 levels I guess)
by JIA Pei 19 Apr '11

19 Apr '11

Hi, to whom it may concern: It looks like many Boost users are arguing that "bjam won't be successfully produced". By reading bootstrap.bat, around line 13, you may notice something like "../../../../******", Yes, that means, Boost root directory must be put at least 4 levels (directory depth). This seems to be a bug of current Boost 1.46.1 Rgds JIA -- Email: jp4work(a)gmail.com cell: +1 7783185816 Welcome to Vision Open http://www.visionopen.com

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[network] Release 0.9.0
by Dean Michael Berris 19 Apr '11

19 Apr '11

Good day everyone, apologies for the cross-post. I just wanted to point everyone interested in the development of the cpp-netlib project to the 0.9.0 release announcement over at C++ Soup: http://cplusplus-soup.com/2011/04/18/cpp-netlib-0-9-0-released/ -- more information about what happened in the library between the beta and the official release can be found there. As earlier mentioned, this version is the pre-1.0 snapshot that is being officially submitted to the Boost C++ Library as Boost.Network. I would like to ask the review wizards to please accept this announcement as a request to put Boost.Network/cpp-netlib into the review queue pending a review manager. I would greatly appreciate volunteers who would like to be the review manager(s) for the Boost.Network review. Have a good one and I definitely hope this helps. Cheers from down under! -- Dean Michael Berris http://about.me/deanberris

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[OT] Boost Users/Developers Down Under?
by Dean Michael Berris 19 Apr '11

19 Apr '11

Hey Everyone! Apologies for the cross post and off-topic, but I just moved to Sydney, Australia and I was wondering whether there are any Boost users/developers that are based here who'd like to get together for a geek out session somewhere in the city? I tried to look at the Boost Users Map (http://goo.gl/O1I15) and I only saw one other Boost user in the area -- maybe there are others lurking around who'd be interested in a meet-up here? :) Cheers from down under! :D -- Dean Michael Berris http://about.me/deanberris

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