November 2007 - Boost-users

MPL: flatten implementation not working
by Andreas Klöckner 25 Dec '07

25 Dec '07

Hi all, I came up with the following implementation of a "flatten" operation that turns a sequence of sequences into a flat list: 8< ------------------------------------------------------------------- #include <iostream> #include <boost/mpl/vector.hpp> #include <boost/mpl/vector_c.hpp> #include <boost/mpl/clear.hpp> #include <boost/mpl/fold.hpp> #include <boost/mpl/copy.hpp> #include <boost/mpl/placeholders.hpp> #include <boost/mpl/back_inserter.hpp> #include <boost/mpl/size.hpp> template<class Sequence> struct flatten { typedef typename boost::mpl::fold< Sequence, typename boost::mpl::clear<Sequence>::type, typename boost::mpl::copy< boost::mpl::_2, boost::mpl::back_inserter<boost::mpl::_1> >::type >::type type; }; typedef flatten< boost::mpl::vector< boost::mpl::vector_c<int, 0, 1, 2, 3>, boost::mpl::vector_c<int, 4, 5, 6> > >::type flatvec; int main() { std::cout << boost::mpl::size<flatvec>::value << std::endl; } 8< ------------------------------------------------------------------- It compiles (using gcc 4.2.1), but prints 0 instead of the expected 7. What am I doing wrong? Thanks for your help Andreas

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Iterator over values of std::map<K, V>
by John Kiopela 04 Dec '07

04 Dec '07

Hi all, I have been browsing through the docs, but I couldn't find anything useful. Does Boost have a std::map<K, V>::iterator adaptor which iterates over the values of the map only. That is, I would like to have an iterator of which operator*() function returns V, instead of std::pair<K, V>. My data is stored in a std::map<K, V> and I would to allow my users to iterate over the values. If it's not here, I'll make one myself. It shouldn't be that hard. Thanks in advance. Kind regards, John

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C++ Performance
by nisha kannookadan 04 Dec '07

04 Dec '07

Hi everybody Im a quite new boost user and I wonder, why C++ Program is so slow. I wrote a program, and I have the same program in Matlab, I expected that my C++ version is much faster, but its not. I use matrices, vectors, matrix- and vector proxies. Do some solving and compute calculations with prod, element_div, etc.. Is boost in general slower than matlab, should I use something else? Id be real happy about any help. Regards Nisha K PS: This question was already in the developer forum. _________________________________________________________________ Invite your mail contacts to join your friends list with Windows Live Spaces. It's easy! http://spaces.live.com/spacesapi.aspx?wx_action=create&wx_url=/friends.aspx…

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Simple Linking Error
by Daniel 03 Dec '07

03 Dec '07

I wrote a simple "Hello, world!" program to test if boost/asio was working correctly: #include <iostream> #include <boost/date_time/posix_time/posix_time.hpp> int main() { std::cout << "Hello, world!\n"; return 0; } But, I get this: (GCC C++ 4.1.2/Linux version 2.6.22-gentoo-r8) test.cpp:(.text+0x10b): undefined reference to `boost::system::get_system_category()' test.cpp:(.text+0x115): undefined reference to `boost::system::get_posix_category()' test.cpp:(.text+0x11f): undefined reference to `boost::system::get_posix_category()' test.cpp:(.text+0x129): undefined reference to `boost::system::get_system_category()' This happens when I used '#include <boost/date_time/posix_time/posix_time.hpp>' I can't figure out what I'm missing

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BGL : maximum weighted matching
by Alessio Dore 01 Dec '07

01 Dec '07

Dear all, I am implementing an algorithm for which I would need to compute the maximum weighted matching of a bipartite graphs. I have seen that LEDA libraries has this sort of functions but their license is restrictive. BGL allows maximum cardinality matching but, if I understood well, it works for non-weighted graphs. In a previous message on this list it was mentioned that this functionality could have been added but I didn't find it. Is it available? Does anyone of you know if there are other libraries to perform it? Thanks. Regrads, Alessio

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[statechart] context sensitive history
by Chris Paulse 01 Dec '07

01 Dec '07

I have the following requirement: States A and B, where B has two substates B1 and B2. When transition occurs from B to A, and then from A back to B, under some conditions it is desired for B1 to be the initial substate, while in others we would like the substate to be chosen based on B's shallow history. Is there a concise way to obtain this behavior from the statecharts library? Thanks, Chris

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Building Python.Boost 2 with VC
by Marko Bozikovic 30 Nov '07

30 Nov '07

Hi all, I'm having problems building Boost.Python with VC 2003. I'm reading the howto, but I must be missing something. My Python 2.4 is installed in C:\Python (using official Windows installer) My user-config.jam looks like this: import toolset : using ; using msvc : 7.1 ; using python : 2.4 : C:\\Python ; (I have tried C:\Python and C:/Python, no luck) When I run bjam: tools\bjam.exe --with-python I get the following error: WARNING: No python installation configured and autoconfiguration failed. See http://www.boost.org/libs/python/doc/building.html for configuration instructions or pass --without-python to suppress this message and silently skip all Boost.Python targets warning: Python location is not configured warning: the Boost.Python library won't be built ...found 1 target... user-config.jam is begin read, because bjam reports errors in it. What am I missing? Thank you, -- Marko ICQ: 5990814 I'm not under the alkafluence of inkahol that some thinkle peep I am. It's just the drunker I sit here the longer I get.

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Serialization: Visual C+ Template Bug ?
by Oliver Kania 30 Nov '07

30 Nov '07

Hello ! When linking a program that consists only of main.cpp with a library that serializes a class "Palo Cllient" I get the following message (sry for the mess): ================================================== error LNK2019: unresolved external symbol "private: void __thiscall jedox::palo::PaloClient::serialize<class boost::archive::text_oarchive>(class boost::archive::text_oarchive &,unsigned int)" (??$serialize@ Vtext_oarchive@archive@boost@@@ PaloClient@palo@jedox@@AAEXAAVtext_oarchive@archive@boost@@I@Z) referenced in function "public: static void __cdecl boost::serialization::access::serialize<class boost::archive::text_oarchive,class jedox::palo::PaloClient>(class boost::archive::text_oarchive &,class jedox::palo::PaloClient &,unsigned int)" (??$serialize@ Vtext_oarchive@archive@boost@@VPaloClient@palo@jedox@@@ access@serialization@boost@@SAXAAVtext_oarchive@archive@2@AAVPaloClient@ palo@jedox@@I@Z) ================================================== This happens even though I do NOT explicitly serialize anything. Main.cpp includes: #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> For the class PaloClient, I do use the Pimpl idiom and serialize as it is recommended in the documentation: PaloClient.cpp: -------------------------------------------------------------- #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/scoped_ptr.hpp> .... template<class Archive> void PaloClient::serialize( Archive &ar, const unsigned int version ) { ar & m_PaloClientImpl; } template void PaloClient::serialize<boost::archive::text_iarchive>( boost::archive::text_iarchive & ar, const unsigned int file_version ); template void PaloClient::serialize<boost::archive::text_oarchive>( boost::archive::text_oarchive & ar, const unsigned int file_version ); ------------------------------------------------------------------------ Now, when I change this to void PaloClient::serialize(boost::archive::text_iarchive & ar, const unsigned int file_version) { ar & m_PaloClientImpl; } void PaloClient::serialize (boost::archive::text_oarchive & ar, const unsigned int file_version) { ar & m_PaloClientImpl; } The linkage error disappears. I guess this is a Visual C++ compiler problem but I wanted to post this in case someone else has similar problems. Kind regards, Oliver PS: Thanks for this great serialization library, it saved me many weeks of programming.

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[statechart] round trip eng. diagramming tool
by Chris Paulse 30 Nov '07

30 Nov '07

I seem to remember seeing an open request for a diagramming tool for Boost statecharts that would be similar in concept to the Rhapsody product. Has there been any further development on this front? Thanks. Chris

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boost::serialization and boost::shared_ptr are not working on tree data structure uses PIMPL idiom
by Youhei Murakami 29 Nov '07

29 Nov '07

Hello everyone. I tried to serialize tree data structure. Tree-structure's "node"-class holds "Impl"-structure and Impl-structure holds child nodes as vector<shared_ptr<node> >. Problems occur when serializing a tree structure that was constructed using above structures. Compile errors not occur, but run-time error occures at serialization of input-stream. If exists someone who knows the reason of it., please teach me that. please god bless me! A problematic souce code has been written below and is attached on this mail. [Emveironment] -Windows XP 64bit -Visual Studio 2005 sp1 -boost-1_34_1 #include <iostream> #include <fstream> #include <cstdlib> #include <vector> #include <boost/shared_ptr.hpp> #include <boost/intrusive_ptr.hpp> #include <boost/serialization/serialization.hpp> #include <boost/serialization/string.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/shared_ptr.hpp> #include <boost/serialization/version.hpp> #include <boost/serialization/base_object.hpp> #include <boost/serialization/tracking.hpp> #include <boost/serialization/is_abstract.hpp> #include <boost/serialization/nvp.hpp> #define BOOST_LIB_NAME boost_serialization #include <boost/config/auto_link.hpp> #include <boost/archive/text_woarchive.hpp> #include <boost/archive/text_wiarchive.hpp> #include <boost/serialization/export.hpp> #include <boost/serialization/split_member.hpp> using namespace std; using namespace boost; using namespace boost::serialization; namespace test { class nodebase { public: typedef shared_ptr<nodebase> NodePointer; typedef vector<NodePointer> Children; typedef Children::iterator ChildIterator; public: nodebase(){} nodebase( const wstring &n ) : name(n) {} virtual ~nodebase(){} wstring getname() { return name; } void setname( const wstring &newname ) { name = newname; } private: wstring name; private: friend class serialization::access; template <class Archive> void serialize( Archive &ar, const unsigned int version ) { ar.register_type<nodebase>(); ar & name; } public: virtual void SetParent( const NodePointer &parent ) = 0; virtual Children GetChildren( void ) = 0; virtual void AddChild( const NodePointer &child ) = 0; virtual void RemoveChild( const NodePointer &child ) = 0; virtual void Traverse( const NodePointer &root ) = 0; }; class node : public nodebase { private: struct Impl { Impl() {} Impl( const Children &v ) : children(v) {} Impl( const Children &v, const NodePointer &p ) : children(v), parent(p) {} public: Children children; NodePointer parent; private: friend class serialization::access; template <class Archive> void serialize( Archive &ar, const unsigned int version ) { ar.register_type<Impl>(); ar & children; //ar & parent; } }; shared_ptr<Impl> pimpl; public: // constructor/destructor node() : pimpl( new Impl ) {} node( const wstring &n ) : nodebase(n), pimpl( new Impl ) {} node( const Children &v ) : pimpl( new Impl( v ) ) {} node( const Children &v, const NodePointer &p ) : pimpl( new Impl( v, p ) ) {} private: // serialization friend class serialization::access; template <class Archive> void serialize( Archive &ar, const unsigned int version ) { base_object<nodebase>(*this); void_cast_register<node, nodebase>(); ar.register_type<node>(); ar & pimpl; } public: // operations virtual void SetParent( const NodePointer &p ) { pimpl->parent = p; } virtual Children GetChildren( void ) { return pimpl->children; } virtual void AddChild( const NodePointer &child ) { this->pimpl->children.push_back( child ); } virtual void RemoveChild( const shared_ptr<nodebase> &child ) { for( ChildIterator i = pimpl->children.begin(); i != pimpl->children.end(); i++ ) { if( (*i).get() == child.get() ) { pimpl->children.erase( i ); break; } } } virtual void Traverse( const shared_ptr<nodebase> &node ) { if( !node ) { return; } #ifdef _DEBUG wcout << node->getname() << endl; #endif Children children = node->GetChildren(); for( ChildIterator i = children.begin(); i != children.end(); i++ ) { Traverse( *i ); } } void print() { for( Children::iterator i = pimpl->children.begin(); i != pimpl->children.end(); i++ ) { wcout << i->get()->getname() << endl; } } }; }; BOOST_CLASS_TRACKING(test::nodebase, boost::serialization::track_always); BOOST_CLASS_TRACKING(test::node, boost::serialization::track_always); int _tmain(int argc, _TCHAR* argv[]) { using namespace test; { node::NodePointer root( new node(wstring(L"root")) ); node::NodePointer c1( new node(wstring(L"c1")) ); node::NodePointer c2( new node(wstring(L"c2")) ); node::NodePointer c3( new node(wstring(L"c3")) ); node::NodePointer c4( new node(wstring(L"c4")) ); node::NodePointer c5( new node(wstring(L"c5")) ); c3->AddChild( c5 ); c1->AddChild( c3 ); c2->AddChild( c4 ); root->AddChild( c1 ); root->AddChild( c2 ); root->Traverse( root ); { // output wofstream ofile( "serialized.txt" ); try { archive::text_woarchive oa( ofile ); oa << (const node&)(*root); } catch( boost::archive::archive_exception &e ) { cout << "At the output : " << e.what() << endl; getchar(); ofile.close(); exit(1); } ofile.close(); } node::NodePointer in; { // input wifstream ifile( "serialized.txt" ); try { archive::text_wiarchive ia( ifile ); ia >> in; } catch( boost::archive::archive_exception &e ) { cout << "At the input : " << e.what() << endl; getchar(); ifile.close(); exit(e.code); } ifile.close(); } } getchar(); return 0; }

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