- Boost-users - lists.boost.org

[iostreams] replacement of std::ifstream, review request
by Sascha Ochsenknecht 23 Apr '07

23 Apr '07

Hi, I made a library which gets an std::ifstream and read a certain file format. Now I would like to support also gzip compressed input files, but it should also support not compressed files. I used boost::iostreams to implement a new stream class which should replace the std::ifstream in my library. Following functions are called from std::ifstream: - std::ifstream(const char*) - read(...) - seek(...) - close(...) My question is, is everything done correctly or is there a more elegant way to implement this? I'm not a stream expert, so I doubt if I do it in a good way :-). Would be great if someone from the experts can have a look to it and review it. Thanks in advance, Sascha I derived my class from boost::iostreams::filtering_istream, here is my implementation: #ifndef PAT_INPUTSTREAM_H #define PAT_INPUTSTREAM_H #include <boost/iostreams/device/file.hpp> #include <boost/iostreams/filter/gzip.hpp> #include <boost/iostreams/filtering_stream.hpp> #include <string> namespace my { namespace io = boost::iostreams; /*! Check if a given file is a (gzipped-)compressed format It is using functions from zlib */ bool isCompressed(const char* p_name); /*! \class ifstream Special input stream to handle compressed files. After opening an my::ifstream, it should be checked with is_open() if it is openend correctly. */ class ifstream : public io::filtering_istream { private: std::string _name; // the filename is needed for re-opening in seek() public: ifstream(const char* p_name) : _name(p_name) { if (isCompressed(p_name)) { io::filtering_istream::push(io::gzip_decompressor()); io::filtering_istream::push(io::file_source(p_name, std::ios::binary)); } else { io::filtering_istream::push(io::file_source(p_name)); } } bool open(const char* p_name) { if (!is_open()) { _name = p_name; if (isCompressed(p_name)) { io::filtering_istream::push(io::gzip_decompressor()); io::filtering_istream::push(io::file_source(p_name, std::ios::binary)); } else { io::filtering_istream::push(io::file_source(p_name)); } } return is_open(); } void close() { if (is_open()) { while (io::filtering_istream::size()) { io::filtering_istream::pop(); } } } bool is_open() { if (io::filtering_istream::size()) { // the last components is the file device io::file_source* device = io::filtering_istream::component<io::file_source>(io::filtering_istream::size()-1); if (device) return device->is_open(); } return false; } ifstream& seekg(std::streampos p_pos) { // seek means close the stream // and read until position is reached were we // want to be if (is_open()) { close(); if (open(_name.c_str())) { const std::streampos PAT_BLOCK_SIZE = 1024; char* buf = new char[PAT_BLOCK_SIZE]; while (p_pos) { if (p_pos / PAT_BLOCK_SIZE) { read(buf, PAT_BLOCK_SIZE); p_pos -= PAT_BLOCK_SIZE; } else { read(buf, p_pos % PAT_BLOCK_SIZE); p_pos -= (p_pos % PAT_BLOCK_SIZE); } } delete [] buf; } } return *this; } }; } // end of namespace pat #endif

1 0

[program_options] missing typed_value implicit()
by Romulus 23 Apr '07

23 Apr '07

Hi everybody, I'm trying the program_options library, I'd like to create my own options groups, but when i compile (using -lboost_program_options) option_groups.cpp from the example directory, i'm told that "implicit()" method from the typed_value class doesn't exist. Btw it doesn't appear in http://www.boost.org/doc/html/typed_value.html What is "implicit()" supposed to do, is it different from "default_value()" ? How can i solve this problem ? Here is the error message: option_groups.cpp: In function 'int main(int, char**)': option_groups.cpp:42: error: 'class boost::program_options::typed_value<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, char>' has no member named 'implicit' Regards -- Romuald THION Doctorant level 3.0 "la vie, c'est comme un jeu mal foutu dont on ne connait pas les règles et où il n'y a pas de sauvegardes"

2 1

Including boost threads
by Christian Mol 23 Apr '07

23 Apr '07

Hello, Probably a newbie question, but here it goes: if I include the boost thread as follows #include <boost/thread/thread.hpp> and try to compile my library in MSVC++ 2005, I get a lot of errors in c:\boost\include\boost-1_33_1\boost\bind\mem_fn_template.hpp I have included a piece of the errorlog next: 3>c:\boost\include\boost-1_33_1\boost\bind\mem_fn_template.hpp(120) : error C2917: '_av *' : invalid template-parameter 3>c:\boost\include\boost-1_33_1\boost\bind\mem_fn_template.hpp(126) : error C2146: syntax error : missing ';' before identifier 'second_argument_type' 3> c:\boost\include\boost-1_33_1\boost\bind\mem_fn_template.hpp(171) : see reference to class template instantiation 'boost::_mfi::mf1<R,T,_av>' being compiled 3>c:\boost\include\boost-1_33_1\boost\bind\mem_fn_template.hpp(126) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int 3>c:\boost\include\boost-1_33_1\boost\bind\mem_fn_template.hpp(126) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int ...... ...... >c:\boost\include\boost-1_33_1\boost\bind\mem_fn_template.hpp(581) : error C2917: '_av *' : invalid template-parameter 3>c:\boost\include\boost-1_33_1\boost\bind\mem_fn_template.hpp(581) : error C2991: redefinition of template parameter '_av' 3> c:\boost\include\boost-1_33_1\boost\bind\mem_fn_template.hpp(581) : see declaration of '_av' 3>c:\boost\include\boost-1_33_1\boost\bind\mem_fn_template.hpp(581) : fatal error C1003: error count exceeds 100; stopping compilation Could someone give me any pointers to what could be the problem? When using it in a very simple program, it does work. Including it in my quite large library it does not work. Kind regards, Christian

2 2

Boost and Intellisense...
by Graham Reitz 23 Apr '07

23 Apr '07

This is probably a little out of scope but I am hoping that someone has gotten this to work. A code line like this: boost::filesystem::path working_path_a( boost::filesystem::current_path() ); ...causes vstudio 2005 intellisense to stop working. It says this 'No additional Information Available' at the bottom. Anything before that line and intellisense works fine and anything after it doesn't. Any help would be greatly appreciated. As a relatively new user to boost having this feature really helps out. Thanks, Graham

9 10

[boost][thread] boost::thread::condition documentation error
by David Callu 23 Apr '07

23 Apr '07

Hi, I found an error in the boost::thread::condition documentation. The member-function template <typename L, typename Pr> bool timed_wait(L& lock, const xtime& xt, Pr pred) is documented like this template<typename ScopedLock, typename Pred> bool timed_wait(ScopedLock&, Pred); The "const xtime&" parameter is discard. Regards David Callu

1 0

[tribool] indeterminate becomes false
by Ken Klose 23 Apr '07

23 Apr '07

tribool theBool(indeterminate); cout << "theBool <" << boolalpha << theBool << ">" << endl; prints out theBool <false> What am I missing? An #include? A 'using' declaration? Both? Thanks, Ken

2 1

Re: [Boost-users] [Serialization, XML] - how to get info "where am i?" in serialization helper (encoding is not recursive)?
by Frank Bergemann 23 Apr '07

23 Apr '07

Hi Robert, > -----Ursprüngliche Nachricht----- > Von: boost-users(a)lists.boost.org > Gesendet: 23.04.07 01:37:58 > An: boost-users(a)lists.boost.org > Betreff: Re: [Boost-users] [Serialization, XML] - how to get info "where am i?" in serialization helper (encoding is not recursive)? > > Frank Bergemann wrote: > > i use an external XML format for configuration of CORBA (MICO) data > > and managed to align that with boost::serialization > > (To not write my own encoder/decoder and to minimize efforts for my > > module, in case the customer wants more CORBA objects/methods in > > future. Actually i think it would be a good options to let generate > > the boost::serialitzation helper file directly by MICO idl compiler.) > > What is the boost::serialitzation helper file? Oh maybe its what i called a > wrapper i meant the serialize(...) functions. The ones, which are related to the CORBA data types are plain simple now, directly related to the IDL file - e.g. template<class Archive> void serialize(Archive & ar, ::EmiHLRINData::HLRINData_V4::DCsiList_s &pInstance, const unsigned int version) { ar & make_nvp_wrapper( "d_csi_opt", pInstance.d_csi_opt ); ar & make_nvp_wrapper( "neg_ph_vlr", pInstance.neg_ph_vlr ); ar & make_nvp_wrapper( "cap", pInstance.cap ); ar & make_nvp_wrapper( "d_csi", pInstance.d_csi ); ar & make_nvp_wrapper( "lowph", pInstance.lowph ); ar & make_nvp_wrapper( "lowac", pInstance.lowac ); } I saved it in a file.cc.template and let it be expanded for the Archives i use (e.g. file_xml_oarchive.cc). So i can pre-compile the whole stuff in a library. And only re-compile, if the IDL files change. ( Using templates it took ages to compile my module :-) ) > > > OK, for this now i have to check, that the (external, non by > > boost::serialization generated) XML image is _actually_ compliant with > > C/C++ data structures - especially for dynamic sized data. That is > > also covered now, the checks do fine. > > How much time/effort did it take to do this? > Was not that much. I have a XML "catalogue" of CORBA commands, for each cmd referring to CORBA object, method of object & related root data objects (holding event/subscriber variables inside, to be expanded). Then I use boost::serialization save(xml_oarchive,...) to create a *dummy* reference object. I traverse this one with some XML lib. And while traversing, i lookup corresponding positions in my XML formatted configuration file (for data to fill-into the boost::serialization image) and update the value in boost::serialization XML image. Then i use load(xml_oarchive, ...) to create the C/C++ object, populated with my "real" data now. I save all the objects needed for a command in a boost::any container (for invoking a generic CORBA-object/method dispatcher). All this alignment stuff will be shifted to process startup phase. In the end it's better than writing my own XML decoder for each CORBA data object. It is much more generic using your boost::serialization lib :-) > > But what i didn't manage is to get the _location_ of error in the XML > > file - in case there is an error. > > Hmmm - location as ? point to the line/character? current name? or ? location in XML data structure (XML-path). > > > opsc_hlr :2204 084723:D:### invoked for <value> > > opsc_hlr :2204 084723:D:### c'tor > > opsc_hlr :2204 084723:D:### done for <value> > > opsc_hlr :2204 084723:D:### d'tor > > > So there is no recursion(???). > > > Is there another way to get a "where am i" information within a > > serialize (load/save) helper? > > make_...wrapper is not recurssive, save/load are. > > I would derive from xml_?archive and override the save(NVP(T)..) and/or > load(NVP...) to capture/whatever the tags as they are read/writting. Don't > forget to call the original save/load. Could you pls refer to short example for deriving from xml_?archive ? > Robert Ramey > \Frank _______________________________________________________________ SMS schreiben mit WEB.DE FreeMail - einfach, schnell und kostenguenstig. Jetzt gleich testen! http://f.web.de/?mc=021192

1 0

[Serialization, XML] - how to get info "where am i?" in serialization helper (encoding is not recursive)?
by Frank Bergemann 22 Apr '07

22 Apr '07

i use an external XML format for configuration of CORBA (MICO) data and managed to align that with boost::serialization (To not write my own encoder/decoder and to minimize efforts for my module, in case the customer wants more CORBA objects/methods in future. Actually i think it would be a good options to let generate the boost::serialitzation helper file directly by MICO idl compiler.) OK, for this now i have to check, that the (external, non by boost::serialization generated) XML image is _actually_ compliant with C/C++ data structures - especially for dynamic sized data. That is also covered now, the checks do fine. But what i didn't manage is to get the _location_ of error in the XML file - in case there is an error. I tried use an make_nvp_wrapper: class MakeNVPPathConcat { std::string org; public: static std::string make_nvp_path_; // TODO: make private, use accessor MakeNVPPathConcat(std::string name) { org = make_nvp_path_; make_nvp_path_ += (make_nvp_path_.empty())? "" : "::"; make_nvp_path_ += name; } ~MakeNVPPathConcat() { make_nvp_path_ = org; } }; namespace boost { namespace serialization { /************************************************ * * boost::serialization::make_nvp(...) wrapper * ************************************************/ template<class T> inline #ifndef BOOST_NO_FUNCTION_TEMPLATE_ORDERING const #endif boost::serialization::nvp<T> make_nvp_wrapper (const char * name, T & t ) { std::string strName ( name ); MakeNVPPathConcat makeNVPPathConcat( strName ); return boost::serialization::make_nvp<T>( name, t ); } } // namespace serialization } // namespace boost Then using the ( i hoped ) recursively concatenated path information e.g. here: template<class Archive, int TID, int max> void load ( Archive & ar, BoundedSequenceTmpl<CORBA::Short, TID, max> &p, const unsigned int version) { std::string const myname("boost::serialization::load[BoundedSequenceTmpl<CORBA::Short, TID, max>]"); std::string str; ar & make_nvp_wrapper("value", str); std::string::size_type strlength = str.size(); if (strlength > p.maximum()) { std::ostringstream err; err <<myname << " - internal error: can't import XML image for <" << MakeNVPPathConcat::make_nvp_path_ << "> (type CORBA object BoundedSequenceTmpl<CORBA::Short, TID, max>) - size #" << strlength << " exceeds maximum length #" << p.maximum(); throw std::runtime_error(err.str()); } p.length(strlength); for (std::string::size_type pos=0; pos<strlength; ++pos) { p[pos] = str.at(pos); } } But it didn't work. I was 1st wondering if my MakeNVPPathConcat might go out of scope too early. But finally i found out, that the serialize (load&save) helpers are not invoked recursively(???) Because if i use a modified version of my wrapper: class MakeNVPPathConcat // TODO: hide this one { std::string org; public: // TODO: make private, use accessor static std::string make_nvp_path_; MakeNVPPathConcat(std::string name) { OUSTprotoDebug("### c'tor"); org = make_nvp_path_; make_nvp_path_ += (make_nvp_path_.empty())? "" : "::"; make_nvp_path_ += name; } ~MakeNVPPathConcat() { // make_nvp_path_ = org; OUSTprotoDebug("### d'tor"); make_nvp_path_ += "-- reset --"; } }; namespace boost { namespace serialization { /************************************************ * * boost::serialization::make_nvp(...) wrapper * ************************************************/ template<class T> inline #ifndef BOOST_NO_FUNCTION_TEMPLATE_ORDERING const #endif boost::serialization::nvp<T> make_nvp_wrapper (const char * name, T & t ) { OUSTprotoDebug("### invoked for <%s>", name); std::string strName ( name ); MakeNVPPathConcat makeNVPPathConcat( strName ); boost::serialization::nvp<T> ret = boost::serialization::make_nvp<T>( name, t ); OUSTprotoDebug("### done for <%s>", name); return ret; } } // namespace serialization } // namespace boost The result is: opsc_hlr :2204 084723:D:### invoked for <pModifyHlrSubscriberIn> opsc_hlr :2204 084723:D:### c'tor opsc_hlr :2204 084723:D:### done for <pModifyHlrSubscriberIn> opsc_hlr :2204 084723:D:### d'tor opsc_hlr :2204 084723:D:### invoked for <imsi> opsc_hlr :2204 084723:D:### c'tor opsc_hlr :2204 084723:D:### done for <imsi> opsc_hlr :2204 084723:D:### d'tor opsc_hlr :2204 084723:D:### invoked for <value> opsc_hlr :2204 084723:D:### c'tor opsc_hlr :2204 084723:D:### done for <value> opsc_hlr :2204 084723:D:### d'tor So there is no recursion(???). Is there another way to get a "where am i" information within a serialize (load/save) helper? - thanks! Regards! Frank

2 1

Re: [Boost-users] [Threads-devel] [thread] Problems with TSS and static thread library
by Roland Schwarz 22 Apr '07

22 Apr '07

Johan Nilsson wrote: > [cross-posting this to boost.threads.devel as I tried putting out a request > for support there as well] > Thank you for analysis, I'll try to look into it as soon as possible. Please do understand, that since we are already in code freeze for 1.34 application of a fix is subject to Thomas Witts approval. Regards, Roland

3 2

BGL: filtered_graph and breadth_first_search.
by Dima F. 22 Apr '07

22 Apr '07

Hello everybody, Often, given a graph G and a subset of it's vertices, there is a need to perform something on an induced graph containing those vertices. I thought about using filtered_graph for that purpose, but for some reason I am unable to use breadth_first_search with a filtered_graph - I get pages of errors from the compiler complaining about something in filtered_graph.hpp, and I don't understand what is the problem. Here is a minimal test program which exemplifies the error. Note that if the line containing a call to a breadth_first_search is commented out, everything compiles properly. What is the problem here? --------------------------------------------------------------------- #include <boost/graph/filtered_graph.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/breadth_first_search.hpp> using namespace std; using namespace boost; template <typename Graph> class induced_graph_filter { public: typedef typename graph_traits<Graph>::edge_descriptor edge_t; typedef typename graph_traits<Graph>::vertex_descriptor vertex_t; induced_graph_filter() {} bool operator()(const vertex_t &v) {} bool operator()(const edge_t &e) {} }; int main() { typedef adjacency_list <listS, vecS, undirectedS> graph_t; graph_t g(2); add_edge(0, 1, g); typedef induced_graph_filter<graph_t> filter_t; filter_t filter; filtered_graph<graph_t, filter_t, filter_t> g2(g, filter); breadth_first_search(g2, 0, visitor(default_bfs_visitor())); } ---------------------------------------------------------------------

2 6