July 2011 - Boost-users - lists.preview.boost.org

How & when to use weak_ptr
by doug livesey 03 Jul '11

03 Jul '11

Hi -- I'm loving how easy shared_ptr makes object handling, but am not sure about how to use weak_ptr. Should I use it in places where previously I would have, say, returned a const reference? For example: struct MyClass { const OtherObject & other_object() const; }; Would become: struct MyClass { weak_ptr<const OtherObject> other_object() const; }; Or is this wasteful, having weak_ptrs construct from shared_ptrs every time I want to access an member object? Or have I missed the point completely? ;) One convention I thought I might adopt would be like this: struct MyClass { void set_other_object( shared_ptr<OtherObject> ); // setter weak_ptr<OtherObject> get_other_object(); // non-const getter const OtherObject & other_object() const; // const getter }; Of course, that could be all kinds of dumb for all kinds of reasons I don't know about. :) Cheers, Doug.

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[numeric::convert] RoundNearest?
by Diederick C. Niehorster 03 Jul '11

03 Jul '11

Dear All, I have just discovered Boost.NumericConvert, useful and a nice effort! However, I am missing a RoundNearest function for float to int conversions, with only RoundEven being provided. RoundEven of course does exactly what it is described to do, rounding .5 to 0 and 1.5 to 2, but i'd like the highschool (usual?) behavior of rounding up when a number exactly in the middle is provided. I can implement it myself by slightly modifying RoundEven of course, but I am wondering if I am missing something obvious or whether there is a good reason why this function is not included? Thank you very much for any thoughts! Best, Dee

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Re: [Boost-users] [chrono] Can not build with intel-win
by Edward Rankin 02 Jul '11

02 Jul '11

> > Message du 13/06/11 09:12 > > De : "Bo Jensen" > > A : boost-users <at> lists.boost.org > > Copie à : > > Objet : [Boost-users] [chrono] Can not build with intel-win > > > > Newest intel C++ release and vs2010, can not build with chrono from trunk. > > > > I get : > > > > pnet.cpp > > ..\..\..\external\boost\boost/chrono/duration.hpp(94): error: expected > > an expression > > && (boost::is_convertible ^ > > > > ..\..\..\external\boost\boost/chrono/duration.hpp(124): error: > > expected an expression > > && (boost::is_convertible ^ > > > > compilation aborted for ..\network\pnet.cpp (code 2) > > > > call "C:\Program Files > > (x86)\Intel\ComposerXE-2011\bin\intel64//iclvars.bat" > nul > > icl @"bin\intel-win\release\threading-multi\pnet.obj.rsp" > > > > Any suggestions welcome. > > Hi, > > I have no idea of what could be the cause of the error. > > Please could you try adding the namespace boost to common_type and send me the preprocesed output. > > Thanks, > Vicente > > Hi, I tried adding the namespace boost to common_type on L93,L95,L123 and L125 but the exact same error appears. Any other ideas? Thanks, Edward

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Using boost function with virtual methods
by przemyslaw.sliwa＠uk.bnpparibas.com 02 Jul '11

02 Jul '11

Hi, I have a simple inheritance: class A {}; class RegressionTestScenario; typedef A CurveGen; typedef boost::shared_ptr<CurveGen> CurveGenPtr; typedef boost::function<void (RegressionTestScenario*, const std::string &)> actionFuntion; typedef boost::shared_ptr<actionFuntion> actionFuntionPtr; class RegressionTestScenario { public: virtual ~RegressionTestScenario() {} virtual void doScenario() = 0; virtual boost::shared_ptr<std::string> fileName() const = 0; virtual boost::shared_ptr<std::string> print() const = 0; virtual void unwrapPackage(const std::string &contents) = 0; protected: typedef std::vector<std::pair<actionFuntionPtr, std::string> > actionCollection; actionCollection m_actionCollection; }; class CurveGenRegressionTestScenario : public RegressionTestScenario { public: virtual void doScenario(); virtual boost::shared_ptr<std::string> fileName() const; virtual boost::shared_ptr<std::string> print() const; virtual void unwrapPackage(const std::string &contents); private: CurveGenPtr m_curveGenPtr; void addAction(const std::string &action); void changeBaseDate(const std::string &argument); void changeStvParameter(const std::string &argument); void changeLtvParameter(const std::string &argument); void changeHalfLife(const std::string &argument); void changeParameterSet(const std::string &argument); void changeCurrencyCouple(const std::string &argument); }; and I am trying to use the following: actionFuntion funPtr; if(params[0]=="BaseDate") funPtr = &CurveGenRegressionTestScenario::changeBaseDate; but it fails. I have no idea why. Could someone give me a hint? This is the output from the compiler: Cheers 1>------ Build started: Project: compare, Configuration: Release Win32 ------ 1>Compiling... 1>RegressionTestMain.cpp 1>D:\Dev\SOHO_NEW\Thirdparty\boost/bind/mem_fn_template.hpp(156) : error C2440: 'newline' : cannot convert from 'RegressionTestScenario *' to 'CurveGenRegressionTestScenario *' 1> Cast from base to derived requires dynamic_cast or static_cast 1> D:\Dev\SOHO_NEW\Thirdparty\boost/bind/mem_fn_template.hpp(171) : see reference to function template instantiation 'R boost::_mfi::mf1<R,T,A1>::call<U,const std::string>(U &,const void *,B1 &) const' being compiled 1> with 1> [ 1> R=void, 1> T=CurveGenRegressionTestScenario, 1> A1=const std::string &, 1> U=RegressionTestScenario *, 1> B1=const std::string 1> ] 1> D:\Dev\SOHO_NEW\Thirdparty\boost/function/function_template.hpp(225) : see reference to function template instantiation 'R boost::_mfi::mf1<R,T,A1>::operator ()<T0>(U &,A1) const' being compiled 1> with 1> [ 1> R=void, 1> T=CurveGenRegressionTestScenario, 1> A1=const std::string &, 1> T0=RegressionTestScenario *, 1> U=RegressionTestScenario * 1> ] 1> D:\Dev\SOHO_NEW\Thirdparty\boost/function/function_template.hpp(222) : while compiling class template member function 'void boost::detail::function::function_void_mem_invoker2<MemberPtr,R,T0,T1>::invoke(boost::detail::function::function_buffer &,T0,T1)' 1> with 1> [ 1> MemberPtr=void (__thiscall CurveGenRegressionTestScenario::* )(const std::string &), 1> R=void, 1> T0=RegressionTestScenario *, 1> T1=const std::basic_string<char,std::char_traits<char>,std::allocator<char>> & 1> ] 1> D:\Dev\SOHO_NEW\Thirdparty\boost/function/function_template.hpp(913) : see reference to class template instantiation 'boost::detail::function::function_void_mem_invoker2<MemberPtr,R,T0,T1>' being compiled 1> with 1> [ 1> MemberPtr=void (__thiscall CurveGenRegressionTestScenario::* )(const std::string &), 1> R=void, 1> T0=RegressionTestScenario *, 1> T1=const std::basic_string<char,std::char_traits<char>,std::allocator<char>> & 1> ] 1> D:\Dev\SOHO_NEW\Thirdparty\boost/function/function_template.hpp(722) : see reference to function template instantiation 'void boost::function2<R,T0,T1>::assign_to<Functor>(Functor)' being compiled 1> with 1> [ 1> R=void, 1> T0=RegressionTestScenario *, 1> T1=const std::basic_string<char,std::char_traits<char>,std::allocator<char>> &, 1> Functor=void (__thiscall CurveGenRegressionTestScenario::* )(const std::string &) 1> ] 1> D:\Dev\SOHO_NEW\Thirdparty\boost/function/function_template.hpp(1065) : see reference to function template instantiation 'boost::function2<R,T0,T1>::function2<void(__thiscall CurveGenRegressionTestScenario::* )(const std::string &)>(Functor,int)' being compiled 1> with 1> [ 1> R=void, 1> T0=RegressionTestScenario *, 1> T1=const std::basic_string<char,std::char_traits<char>,std::allocator<char>> &, 1> Functor=void (__thiscall CurveGenRegressionTestScenario::* )(const std::string &) 1> ] 1> D:\Dev\SOHO_NEW\Thirdparty\boost/function/function_template.hpp(1105) : see reference to function template instantiation 'boost::function<Signature>::function<void(__thiscall CurveGenRegressionTestScenario::* )(const std::string &)>(Functor,int)' being compiled 1> with 1> [ 1> Signature=void (RegressionTestScenario *,const std::string &), 1> Functor=void (__thiscall CurveGenRegressionTestScenario::* )(const std::string &) 1> ] 1> .\RegressionTestMain.cpp(182) : see reference to function template instantiation 'boost::function<Signature> &boost::function<Signature>::operator =<void(__thiscall CurveGenRegressionTestScenario::* )(const std::string &)>(Functor)' being compiled 1> with 1> [ 1> Signature=void (RegressionTestScenario *,const std::string &), 1> Functor=void (__thiscall CurveGenRegressionTestScenario::* )(const std::string &) 1> ] 1>D:\Dev\SOHO_NEW\Thirdparty\boost/bind/mem_fn_template.hpp(156) : error C2647: '->*' : cannot dereference a 'void (__thiscall CurveGenRegressionTestScenario::* const )(A1)' on a 'RegressionTestScenario *' 1> with 1> [ 1> A1=const std::string & 1> ] 1>Build log was saved at "file://d:\Dev\OwnProgs\compare\compare\Release\BuildLog.htm" 1>compare - 2 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== ___________________________________________________________ This e-mail may contain confidential and/or privileged information. 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boost::serializable | Persisting a shared_ptr to XML archive
by doug livesey 02 Jul '11

02 Jul '11

Hi -- I'm trying to serialize an object in a boost::shared_ptr, here: https://github.com/biot023/cell_biots/blob/master/include/game.h#L30 My problem is that the object isn't getting persisted, only the shared_ptr (I think). The result of this save is this: https://gist.github.com/1061413 Can anyone advise me on what I'm doing wrong? I've included <boost/serialization/shared_ptr.hpp>, but I guess there's something else I need to be doing. Any & all help very gratefully received, Doug.

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Re: [Boost-users] [review][assign] Formal review of Assign v2 ongoing
by er 02 Jul '11

02 Jul '11

This was posted to lib.boost.devel, but I meant to post it in boost.user as well: > About your other comments: > - operator| has a similar meaning in Boost.Range under adaptors. > - Feel free to suggest another prefix than 'do'. > - Dot is borrowed from Boost.Assign (1.0). Did you mean dot or %? The dot is a small price to pay for alternating between various ways to insert elements in a container, within one statement: put( cont )( x, y, z ).for_each( range1 )( a, b ).for_each( range2 ); The answer to "[Is it] just a quest to type less when using standard containers?" is yes, as illustrated just above, but it is quite a broad definition of standard containers. Version 2.0 provides macros to broaden it further (which was used to support Boost.MultiArray, for example). As for why such a library should exist, it depends on the degree to which you value the syntax above, which is very similar to Boost.Assign (1.0), in this case. You say "I ordinarily only initialize containers to literals when writing unit tests.". In this case, I think you are right that you can't beat C++0x initializer lists. But, you still may need to fill a container, as above. And also, consider the cases below: #include <vector> #include <queue> #include <string> #include <tuple> #include <boost/assign/v2/include/csv_deque_ext.hpp> int main() { typedef std::string s_; { typedef std::tuple<s_, int> t_; typedef std::vector<t_> v_; v_ v1 = { t_( "a", 1 ), t_( "b", 2 ), t_( "c", 3 ), t_( "d", 4 ), t_( "e", 5 ) }; using namespace boost::assign::v2; v_ v2 = converter( csv_deque<t_, 2>( "a", 1, "b", 2, "c", 3, "d", 4, "e", 5) ); } { typedef std::queue<int> q_; // Not aware that an initializer list works here using namespace boost::assign::v2; q_ q = converter( csv_deque<int, 1>( 1, 2, 3, 4, 5 ) ); } return 0; } > - Prefix _ is reserved for const objects (not sure the proper word for it) And I think this convention appears elsewhere in Boost, such as Boost.Parameter. _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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Overloading boost::hash_value GCC
by André Santee 01 Jul '11

01 Jul '11

I'm having a hard time trying to compile my code here. What I'm doing is to overload the boost::hash_value function to use boost::unordered_map with a custom Vector2 class. My code: // Vector2 hash function namespace boost { inline std::size_t hash_value(Vector2 const& p) { std::size_t seed = 0; boost::hash_combine(seed, p.x); boost::hash_combine(seed, p.y); return seed; } } // namepace boost boost::unordered_map<Vector2, EntityList, boost::hash<Vector2> > buckets;[/code] It compiles and run fine on msvc 9.0 but gcc says the function does not exist (it looks like to me that it does exist!). error message: Compile++ thumb : Application <= BucketManager.cpp In file included from /boost/functional/hash/hash.hpp:510, from /boost/functional/hash.hpp:6, from /boost/unordered/unordered_map.hpp:17, from BucketManager.h:35, from BucketManager.cpp:24: /boost/functional/hash/extensions.hpp: In member function 'size_t boost::hash<T>::operator()(const T&) const [with T = math::Vector2]': /boost/unordered/detail/unique.hpp:183: instantiated from 'typename boost::unordered_detail::hash_unique_table<T>::value_type& boost::unordered_detail::hash_unique_table<T>::operator[](const typename T::key_type&) [with T = boost::unordered_detail::map<math::Vector2, boost::hash<math::Vector2>, std::equal_to<math::Vector2>, std::allocator<std::pair<const math::Vector2, std::list<RenderEntity*> > > >]' /boost/unordered/unordered_map.hpp:406: instantiated from 'T& boost::unordered_map<K, T, H, P, A>::operator[](const K&) [with K = math::Vector2, T = std::list<RenderEntity*>, H = boost::hash<math::Vector2>, P = std::equal_to<math::Vector2>, A = std::allocator<std::pair<const math::Vector2, std::list<RenderEntity*> > >]' BucketManager.cpp:128: instantiated from here /boost/functional/hash/extensions.hpp:176: error: no matching function for call to 'hash_value(const math::Vector2&)' /boost/functional/hash/hash.hpp:136: note: candidates are: size_t boost::hash_value(bool) /boost/functional/hash/hash.hpp:141: note: size_t boost::hash_value(char) /boost/functional/hash/hash.hpp:146: note: size_t boost::hash_value(unsigned char) /boost/functional/hash/hash.hpp:151: note: size_t boost::hash_value(signed char) /boost/functional/hash/hash.hpp:156: note: size_t boost::hash_value(short int) /boost/functional/hash/hash.hpp:161: note: size_t boost::hash_value(short unsigned int) /boost/functional/hash/hash.hpp:166: note: size_t boost::hash_value(int) /boost/functional/hash/hash.hpp:171: note: size_t boost::hash_value(unsigned int) /boost/functional/hash/hash.hpp:176: note: size_t boost::hash_value(long int) /boost/functional/hash/hash.hpp:181: note: size_t boost::hash_value(long unsigned int) /boost/functional/hash/hash.hpp:187: note: size_t boost::hash_value(wchar_t) /boost/functional/hash/hash.hpp:194: note: size_t boost::hash_value(boost::long_long_type) /boost/functional/hash/hash.hpp:199: note: size_t boost::hash_value(boost::ulong_long_type) /boost/functional/hash/hash.hpp:313: note: size_t boost::hash_value(float) /boost/functional/hash/hash.hpp:318: note: size_t boost::hash_value(double) /boost/functional/hash/hash.hpp:323: note: size_t boost::hash_value(long double) make: *** -- André Santee | Desenvolvedor de games andre.santee(a)jera.com.br | +55 67 8127-9528 [image: Facebook]<http://www.facebook.com/pages/Jera-Software-Agil/127079757331746> [image: Facebook] <http://twitter.com/decosantee> [image: Flickr]<http://www.flickr.com/jerasoftware> [image: LinkEdin] <http://www.linkedin.com/companies/jera?trk=fc_badge> <http://www.jera.com.br/>

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problems on iterating over a fusion sequence
by Olaf Peter 01 Jul '11

01 Jul '11

Hi, in the example below, the loop runs forever. What is the reason for this? I'm using trunk 72818 Thanks, Olaf

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Fwd: boost bind
by candy.chiu.ad＠gmail.com 01 Jul '11

01 Jul '11

> Hi, > A boost::bind statement in my code generated the following compilation > error: > 1>Compiling... > 1>CmsPayOffReplication.cpp > 1>.\CmsPayOffReplication.cpp(79) : error C2665: 'boost::bind' : none of > the 2 overloads could convert all the argument types > 1> C:\DiskE\OpenSource\boost_1_45_0\boost/bind/bind.hpp(1420): could > be 'boost::_bi::bind_t > boost::bindarg,QuantLib::Date,QuantLib::Period,QuantLib::Period,QuantLib::Rate>(boost::type,F,A1,A2,A3,A4,A5)' > 1> with > 1> [ > 1> R=double, > 1> F=QuantLibInterface::YieldCurveUtility *, > 1> > L=boost::_bi::list5arg,boost::_bi::valueQuantLib::Date>,boost::_bi::value,boost::_bi::value,boost::_bi::valueRate>>, > 1> T=QuantLibInterface::YieldCurveUtility, > 1> I=1, > 1> A1=boost::arg, > 1> A2=QuantLib::Date, > 1> A3=QuantLib::Period, > 1> A4=QuantLib::Period, > 1> A5=QuantLib::Rate > 1> ] > 1> C:\DiskE\OpenSource\boost_1_45_0\boost/bind/bind.hpp(1512): > or 'boost::_bi::bind_t > boost::bindarg,QuantLib::Date,QuantLib::Period,QuantLib::Period,QuantLib::Rate>(F,A1,A2,A3,A4,A5,A6)' > 1> with > 1> [ > 1> R=boost::_bi::unspecified, > 1> F=double, > 1> L=boost::_bi::list6bi::valueYieldCurveUtility > *>,boost::arg,boost::_bi::value,boost::_bi::value,boost::_bi::valuePeriod>,boost::_bi::valueQuantLib::Rate>>, > 1> T=QuantLibInterface::YieldCurveUtility, > 1> I=1, > 1> A1=QuantLibInterface::YieldCurveUtility *, > 1> A2=boost::arg, > 1> A3=QuantLib::Date, > 1> A4=QuantLib::Period, > 1> A5=QuantLib::Period, > 1> A6=QuantLib::Rate > 1> ] > 1> while trying to match the argument list '(overloaded-function, > QuantLibInterface::YieldCurveUtility *, boost::arg, const QuantLib::Date, > const QuantLib::Period, const QuantLib::Period, QuantLib::Rate)' > 1> with > 1> [ > 1> I=1 > 1> ] > I replicated the set up of the objects in simpler project, and the bind > statement compiled successfully. Can anyone shred some light on the cause > of the error? > Here is how I call boost::bind > QuantLib::Date date; > QuantLib::Period p1,p2; > QuantLib::Rate rate; > // initialization of date, p1, p2, rate > boost::functionYieldTermStructure>) > > priceWithCurve = boost::bind( > &YieldCurveUtility::priceSwap, > &YieldCurveUtility::instance(), _1, > date, period1, period2, rate ); > Thank you.

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[Boost-log v1][Boost 1_46_1][MinGW 4.4.0][Windows 7] Finaly builded (partially) !!!
by Aman Feri 01 Jul '11

01 Jul '11

Hello I finally partially builded Boost_log v1 with Boost 1_46_1 using MinGW (gcc 4.4.0) on windows 7. It's a great victory for me, because it took a long time. I contribute here, if anyone need it or is able to make it work better. -------------- Error 1 -------------- Title : Compiling Boost_log v1 with Boost 1_46_1 including Filesystem v3 Symptom : error: 'external_string_type' is not a member of 'boost::filesystem3::wpath' Fix : using Filesystem_version 2 (thanks http://stackoverflow.com/questions/6076405/what-is-boost-log-how-to-get-it-… ) (don't forget to #define BOOST_FILESYSTEM_VERSION 2 in your projects using Boost_log) -------------- Error 2 -------------- Title : Using windows path Symptom : "windres.exe" + "C:\Program is not recognize as a valid command" (free translation) Fix : reinstalling MinGW, in a directory without space allowed bjam to find windres.exe -------------- Error 3 -------------- Title : (maybe a boost log v1 bug ?) Symptom : libs\log\src\event_log_backend.cpp:55: error: external linkage required for symbol 'boost::log_mt_nt5::sinks::event_log::success' because of 'dllexport' attribute Fix (seams to work, but confirmation still needed) : replace libs\log\src\event_log_backend.cpp line 55/56/57/58 from : BOOST_LOG_EXPORT const event_type_t ... to extern BOOST_LOG_EXPORT const event_type_t ... -------------- Error 4 -------------- Title : comeback of error 1 Symptom : Error 1 reproduce only on "release" build (but debug was build) Fix : no fix. Already spended 4 hours on this. I just use debug dll. Note : it implies i use debug dll for filesystem, system, thread and regex too (maybe implying i use both debug and release version in my final project) -------------- Error 5 -------------- Title : linking my project (the one that use boost log) with signle threaded instead of multi threaded Symptom : undefined reference to `boost::log_mt_nt5::basic_attribute_set<char>::~basic_attribute_set()' Fix : link your project using log v1 with libboost_log-mgw44-mt-d-1_46_1.dll not libboost_log-mgw44-d-1_46_1.dll (note the -d for "debug because i couldn't build the release cf error 4) Have a nice build !

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