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Saving to older version
by at forum 06 Feb '08

06 Feb '08

Hi I am testing boost serialization to integrate it in our software. Actually I am using mfc I want to save an object to an older version? I using the split method (save and load) and I don't find how to pass the version to the save function? "BOOST_SERIALIZATION_NVP(this)" is using the current object version. code : class CMyPoint { friend class boost::serialization::access; protected: int m_nX, m_nY; std::string m_sName; public: CMyPoint() { m_nX = 0; m_nY = 0; m_sName = ""; } CMyPoint(int nX, int nY, std::string sName = "") { m_nX = nX; m_nY = nY; m_sName = sName; } void SetX(int nX) { m_nX = nX; } void SetY(int nY) { m_nY = nY; } virtual void Assign(const CMyPoint &pt) { m_nX = pt.m_nX; m_nY = pt.m_nY; } CMyPoint& operator =(const CMyPoint &pt) { Assign(pt); return *this; } template<class Archive> void save(Archive & ar, const unsigned int version) const { ar & BOOST_SERIALIZATION_NVP(m_nX) & BOOST_SERIALIZATION_NVP(m_nY); if(2 <= version) ar & BOOST_SERIALIZATION_NVP(m_sName); } template<class Archive> void load(Archive & ar, const unsigned int version) { ar & BOOST_SERIALIZATION_NVP(m_nX) & BOOST_SERIALIZATION_NVP(m_nY); if(2 <= version) ar & BOOST_SERIALIZATION_NVP(m_sName); } BOOST_SERIALIZATION_SPLIT_MEMBER() void Save(const char * filename) { std::ofstream ofs(filename); assert(ofs.good()); boost::archive::xml_oarchive oa(ofs); oa << BOOST_SERIALIZATION_NVP(this); } void Load(const char * filename) { std::ifstream ifs(filename); assert(ifs.good()); boost::archive::xml_iarchive ia(ifs); ia >> BOOST_SERIALIZATION_NVP(this); } }; BOOST_CLASS_VERSION(CMyPoint, 2) BOOST_CLASS_EXPORT_GUID(CMyPoint, "CMyPoint") Thank you

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Linker error
by Robert Dailey 06 Feb '08

06 Feb '08

Hi, I'm using Visual Studio 9 on Windows. Up until I the inclusion of <boost/signals.hpp>, my application linked fine. Now I'm getting the following linker error: *LINK : fatal error LNK1104: cannot open file 'libboost_signals-vc90-mt-gd-1_35.lib' *Here is the order of my includes in my precompiled header: #include <boost/timer.hpp> #include <boost/function.hpp> #include <boost/noncopyable.hpp> #include <boost/shared_ptr.hpp> #include <boost/scoped_ptr.hpp> #include <boost/bind.hpp> #include <boost/array.hpp> #include <boost/xpressive/xpressive.hpp> #include <boost/signals.hpp>

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[BGL] Sorting Edges
by John Hood 06 Feb '08

06 Feb '08

Hello, all, Sorry to spam the list over this, but I my need is dire. In reading the boost::graph documentation, I stumbled across an example of sorting a graph's edges (I am trying to implement a bi-directional graph with edge-sorting). I have been searching through the docs, but to no avail. Could some kind soul point me in the right direction? Many thanks. -J

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MACRO to evaluate mpl::size::value as a constant.
by Tim St. Clair 06 Feb '08

06 Feb '08

Is there a MACRO which returns a constant when evaluating the size of an mpl sequence. Here is what I'm trying to do: #define MY_MACRO (N) CREATE_FOO_BAR_FN##N #define SUPERFUNK (CLASSA, ...)\ CLASSA { \ typedef mpl::vector<__VA_ARGS__> v0; \ MY_MACRO ( ??SOME_BOOST_MACRO??(mpl::size<v0>::value) ) \ } \ If seems like this should be possible given that I can do the following: BOOST_MPL_ASSERT_RELATION(mpl::size<v0>::value, ==, 0); -- Regards, Timothy St. Clair [timothysc(a)gmail.com]

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[graph] removing self-edges bug?
by Sebastian Weber 06 Feb '08

06 Feb '08

Hi everyone! I think I've hit a but in the remove_edge(u,v,bg) function in case I want to delete a self-edge. The following code crashes on my machine: using namespace boost; typedef adjacency_list<vecS, vecS, undirectedS > ubase_graph_t; ubase_graph_t bg(5); add_edge(0, 1, bg); add_edge(1, 2, bg); add_edge(3, 4, bg); add_edge(4, 0, bg); add_edge(2, 2, bg); remove_edge(2, 2, bg); However, deleting via edge_descriptors is working: BGL_FORALL_OUTEDGES(2, ed, bg, ubase_graph_t) { if(target(ed, bg) == 2) { remove_edge(ed, bg); break; } } So what is wrong with remove_edge(u, u, bg) if there is a self-edge? My boost version is 1.34.1 and I am using g++ 4.1.2 on an ubuntu gutsy machine. Some info from gdb, but the output is just not usable to me - I have no clue what happens: *** glibc detected *** ../build/tools/gcc/debug/revTest: free(): invalid next size (fast): 0x08085420 *** ======= Backtrace: ========= /lib/tls/i686/cmov/libc.so.6[0xb743bd65] /lib/tls/i686/cmov/libc.so.6(cfree+0x90)[0xb743f800] /usr/lib/libstdc++.so.6(_ZdlPv+0x21)[0xb7603d81] ../build/tools/gcc/debug/revTest[0x804f943] ../build/tools/gcc/debug/revTest[0x804f978] ../build/tools/gcc/debug/revTest[0x8050c7f] ../build/tools/gcc/debug/revTest[0x8050cbf] ../build/tools/gcc/debug/revTest[0x80510f3] ../build/tools/gcc/debug/revTest[0x8051180] ../build/tools/gcc/debug/revTest[0x8049b4b] /lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe0)[0xb73e8050] ../build/tools/gcc/debug/revTest(__gxx_personality_v0+0x81)[0x80497b1] Greetings, Sebastian

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[boost.iostreams] Can't be able to read gzipped file
by Marc Viala Perso 06 Feb '08

06 Feb '08

Hello, During the implementation of a TARFILE module based on Boost.Iostream, I've faced a problem during reading operation of a boost::iostream::filtering_stream<> with a GZip codec. To illustrate it, you will find hereafter a small code snippet that reproduces my problem: namespace io = boost::iostreams ; namespace fs = boost::filesystem ; const fs::path test_file("test.txt.gz") ; const std::string s("Test..................") ; { io::filtering_stream<io::output> ofilter ; ofilter.push(io::gzip_compressor()) ; ofilter.push(io::file_descriptor_sink( test_file.external_file_string() , std::ios::binary)) ; ofilter << s ; } { io::filtering_stream<io::input> ifilter ; ifilter.push(io::gzip_decompressor()) ; ifilter.push(io::file_descriptor_source( test_file.external_file_string() , std::ios::binary)) ; std::string rs ; ifilter >> rs ; // <- Here process is blocked in file_description.cpp @ line 145 //boost::scoped_array<char> buffer(new char[512]) ; //const std::streamsize count = io::read(ifilter, buffer.get(), 512) ; } The problem occurs during the reading operation @ line: "ifilter >> rs": the process is blocked in boost/iostreams/src/file_description.cpp @ line 145 ("if (!::ReadFile(pimpl_->handle_, s, n, &result, NULL))") when this line is executed. I've tried to use boost::iostream::read() template function without more success. I've checked the file after the writing operation w/ 7z and everything is fine at this point. I've tried the same code snippet w/ ZLib and BZip2 codecs without trouble. My environment is: Visual C++ 7.1 Boost 1.34.1 Windows XP SP2 Is there any bug in GZip decompressor with the file_descriptor_source? Or I've missed something? Any help will be appreciated. Best regards, Marc VIALA

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Thread creation overhead & efficiency
by James Sutherland 05 Feb '08

05 Feb '08

I am a new user of boost::thread. After implementing it I found that it slowed down execution of my code. I suspect that it may be due to the overhead of thread creation. I am creating/destroying thread_group ojects many times (tens of thousands) during code execution. Pardon my naïve question, but is this a problem for performance? I noticed some reference to a thread pool on this list. Is a thread pool the best alternative in this situation? Thanks for any guidance, James

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[xpressive] regex_search() question
by Robert Dailey 05 Feb '08

05 Feb '08

Hi, Currently I have the following string: "test anothertest somethinelse skillholder" I'm trying to create a regex that will match each word. For example, the following regex: (\w+) will match each word. However, boost::xpressive::regex_search() stops at the first substring match. I'm looking for a way to make it continue to find matches until the end of the string is met. So when I review the matches at the end of the search, it will have 4 matches, each match representing one word in the string above. The C++ code is below. Note that I only get "test" in my results back, when I expected 3 other words to be in the matches. Can anyone tell me how to make it continue the search beyond the first match? Thank you. std::string classes = "test anothertest somethinelse skillholder"; using namespace boost::xpressive; sregex rex = sregex::compile( "(\\w+)" ); smatch matches; regex_search( classes, matches, rex );

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put problem
by BomBielFil 05 Feb '08

05 Feb '08

Hi I'm new user of boost library I tried to create a graph but I can't modify the weight_map of this graph. In my code: boost::property_map<Triangultion,boost::edge_weight_t>::type weight_map=get(boost::edge_weight,ft); | | put(weight_map,*eit,100); at compile time I've for command "put": "../property_map.hpp:319: error: invalid lvalue in assignment Best regards -Bombielfil-

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Re: [Boost-users] using transform_iterator with std::lower_bound
by Alexis H. Rivera-Rios 05 Feb '08

05 Feb '08

Just so you know, the code compiles fine in VC2005 and Windriver Diab compiler. Gcc 3,4 is the one that complains. Can somebody explain me why that happens? Thanks, Alexis Programming Tutorial: In Python: To do this, do this In Perl: To do this, do this or this or this or this... In C: To do this, do this, but be careful In C++: To do this, do this, but don't do this, be careful of this, watch out for this, and whatever you do, don't do this ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping

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