November 2007 - Boost-users

Serializing abstract classes
by Christoph 03 Nov '07

03 Nov '07

Consider the following class hierarchy: A - B - C1 \- B2 - C2 Is the following correct: * when A is an abstract class then (without any data members!) then I do not need to provide serialization support for this class * when A does have data members (and so does C) but B does not add any data and B furthermore is abstract (so the actuall class will be C1..) then no searialization support is needed for B? Is this correct? Should I provide serialization support for these classes even *if* it is correct? Best regards and thank you Christoph

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boost::concept_check: ConceptConcept missing!
by Mattias Nissler 03 Nov '07

03 Nov '07

Hi, I've just recently started using boost::concept_check. It suits my needs very well and works perfectly so far. However, today I've come across something that is missing: The ConceptConcept! What I mean is a meta concept that checks whether a given template is a concept checking class. It should be relatively straightforward to implement, here is some example code I've cooked up: #include <boost/concept_check.hpp> template<template<typename T> class _TConcept> struct ConceptConcept { /* Instead of int, any type allowed as template parameter should do. */ _TConcept<int> c; void constraints() { /* Require the constraints() function to exist in _TConcept. */ c.constraints(); } }; template<template<typename TX> class T> void function() { boost::function_requires< ConceptConcept<T> >(); } template<typename T> struct NoConcept { }; int main(void) { function<boost::IntegerConcept>(); //function<NoConcept>(); // <- fails, NoConcept::constraints() is missing. } Note that due to the template template technique, this only works for ConceptConcept. Higher meta levels (e.g. ConceptConceptConcept) are not supported by this code. I'd like to see this in boost::concept_check. What do you think? Cheers, - Mattias

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"Getting Started" document : missing documentation of the stdlib flag
by Vincent Torri 03 Nov '07

03 Nov '07

Hello, If I'm not mistaken, to compile boost with STLport, one must pass -stdlib=stlport (or something like that) to bjam. But it's not mentionned in the "Getiing Started" documentation (Unix or Windows), while STLport itself is mentioned. Also, stdlib is mentioned when I launch bjam with --help, --help-options or --help-internal. Can someone add the documentation of the stdlib flag in "Getting Started", please ? (and maybe also in the boost build, to get doc with bjam --help) Thank you Vincent Torri

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How can change library name!
by 鑫赖 03 Nov '07

03 Nov '07

When i build boost library, how can i use "bjam" to control the library naming rules and compiler flags. i use vs2005. when i use regrex library, vc2005 always says that "can't link library boost-regrex-p-1_34_1.lib",but the library name that "bjam" produce is "boost-regrex-1_34_1.lib". The library name i can't remenber clearly,but the difference is character "p". So i want to control the the library naming rules. i don't why vc2005 link boost-regrex-p-1_34_1.lib,not other name just as the "bjam" produced. so i don't familiar with the rules vc2005 link library. ___________________________________________________________ 雅虎邮箱，终生伙伴！ http://mail.yahoo.com.cn/

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SFINAE broken in Visual C++ Express?
by Ovanes Markarian 02 Nov '07

02 Nov '07

Hello! Does anybody else experience a problem using enable_if templates in Visual C++ Express 2005 SP1? I get compiler errors in this code: template<class LookUpType_> typename boost::enable_if_c<is_const, result_type>::type at(LookUpType_ const& key)const { return has_key(view_, key); } template<class LookUpType_> typename boost::disable_if_c<is_const, result_type>::type at(LookUpType_ const& key) { return has_key(view_, key); } It blames that type is not a member of enable_if_c or disable_if_c? This is really strance, since this should not be considered by compiler as a possible template instantiation. is_const is an enum value containing either true or false.

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Mixing Boost thread library and Apache runtime library
by Alex 02 Nov '07

02 Nov '07

Hi, Our current code base uses Apache Runtime Library for handling multithreading code, including threads, concurrency control, etc. We are currently starting to convert to the Boost thread library. During the conversion which might take a while we would like to be able to mix the threads from the APR library with concurrency control objects (mutexes) from the Boost library. Is this ok to do this or will we run into some strange issues? We are currently running the code on Windows and Linux. Please let me know if I can provide any specifics about the APR library to better answer this question. Thank you! Alex

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boost Xpress and Window CE 5.0..help me..!!
by bsakiag 02 Nov '07

02 Nov '07

Hi, all. I want to use boost Xpress on Windows CE 5.0 (w/VS2005) when compile sample code, error occors reason of "btowc()" function. if I comment out ////////////////////////// c_regex_traits.hpp ///////////////////////// #ifndef BOOST_XPRESSIVE_NO_WREGEX /// INTERNAL ONLY template<> inline wchar_t c_regex_traits<wchar_t>::widen(char ch) { using namespace std; return btowc(ch); <<-------------- here!!! } #endif ////////////////////////////////////////////////////////////////////// this function not supported in Windows CE. is there any solution of the compile error? regards, from bstill. ps: when I compile with "BOOST_XPRESSIVE_NO_WREGEX" preprossor, another errors are occur. ________________________________________________________ 존경하는 선생님께 고마움의 메시지 보내고 선물 받으세요! - 모두가 행복한 세상이 됩니다. UCC 참여하기 http://kr.fun.kids.yahoo.com/funnybox/thankyou.html

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Is anyone going to tell me the way to set the WINDOWS variables for BOOST?
by question boost 02 Nov '07

02 Nov '07

Hi, in the boost directory named "boost_1_33_1" I 've downloaded, which directories do I have to indicate to the variables INCLUDE and LIB in order to set them? THANK YOU VERY MUCH, David _________________________________________________________________ Retrouvez Windows Live Messenger sur votre mobile ! http://www.messengersurvotremobile.com

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Re: [Boost-users] Boost-users Digest, Vol 1438, Issue 1
by Pavlo Korzhyk 02 Nov '07

02 Nov '07

It is definitely possible given the resources required:) This will be great to have an application server and a set of APIs and tools for C++. At the moment we have most of the libraries, one main gap is OO-persistance, probably implemented as an ORM. I use boost.serialization, it's cool, but it is not enough IMHO: Library I dream about would serialize separate objects and fetch them when needed from one archive. And boost.serialization doesn't provide neither ACID transactions nor iterators over the content of the archive. There is also a lack of "JSP" compiler - but it's not that hard to implement. So all is needed is to implement these two things, then take Apache, cgixx and you have J2EE in C++. And when you have all the bricks - you don't actually need a specification or a ready to use standard, because putting it all together is (looks like) a piece of cake. It's a lot of work, but it's not that much as "mammoth effort" :) PS Correct me if my comments on the current state of the free C++ libraries is wrong. I listed the problems for which I tried but didn't find any ready-to-use solution. So any hints like "take a look at xyz.sourceforge.net" are highly appreciated. > From: Stefan Kok <stefan(a)opensolutions.co.za> > Subject: [Boost-users] C++ & Enterprise Solutions > To: boost-users(a)lists.boost.org > Message-ID: <1193982052.13506.43.camel(a)kobus.opensol.local> > Content-Type: text/plain > > Dear List > > If this is not the correct list to post to. Then please forgive my > ignorance. > > I have been admiring the work of Boost and its contributors for some > time now. My questions / comments : > > 1) Would their be any benefit to the community, developing a > specification for C++ similar to SUN's J2EE and JEE specification ? > > I do realize this would require a mammoth effort as well as commitment > in terms of resources. > > 2) Is it possible to establish such a project under the open source > banner ? > > Given the commitment and resources required. > > 3) Would this be reinventing the wheel ? > > > I know SUN & Java got there first (the J2EE thing). But C++ does have > some very powerful features which makes it unique in some ways, > templates for one. > > WBR, Pavlo Korzhyk ICQ#155870780

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[boost-users] [program options]
by chun ping wang 02 Nov '07

02 Nov '07

HI how would I use program options to accept multiple input. Example I have a diffieHellmanKeyExchange program running through command prompt. // begin main program #include <iostream> #include <boost/tuple/tuple_io.hpp> #include <boost/program_options.hpp> #include "cppdef/BitOperation.cpp" #include "cppdef/mathfunc.cpp" #include "cppdef/IsPrime.cpp" #include "cppdef/DiffieHellman.cpp" #include <BigInteger.hpp> #include <BigIntegerUtils.hpp> int main( int ac, char* av[] ) { namespace po = boost::program_options; po::options_description desc("Allowed options"); boost::tuple<BigInteger, BigInteger> key_pair; desc.add_options() ("generate", "generates a pair of key") ("secert", po::value(&key_pair), "creates the share secret key"); po::variables_map vm; po::store(po::parse_command_line(ac, av, desc), vm); po::notify(vm); if (vm.count("generate")) { BigInteger my_prime = encryptcpw::random_prime<BigInteger>(&algocpw::Miller_Rabin<BigInteger>, 10); std::cout << "my prime: " << my_prime << "\n"; boost::tuple<BigInteger, BigInteger> pare(encryptcpw::dh_init<BigInteger>( my_prime )); std::cout << "pair of generated number: " << pare << "\n"; } if (vm.count("secert")) { const BigInteger p( encryptcpw::random_prime<BigInteger>(&algocpw::Miller_Rabin<BigInteger>, 10)); std::cout << encryptcpw::dh_secret<BigInteger>( p, boost::tuples::get<0>(key_pair), boost::tuples::get<1>(key_pair)); } } // end program The thing compiles but when I do DiffieHellman.exe --secert 817 697 I get this error. C:\CPW\cs_classes>DiffieHellmanEncrypt --secert 817 697 terminate called after throwing an instance of 'boost::program_options::invalid_ option_value' what(): in option 'secert': invalid option value '817' This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information.

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