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[shared_ptr] Problem refeering back to a parent class.
by Eoin 30 Apr '06

30 Apr '06

Hello, I've a question, I don't know if I'm doing something technically wrong or if my whole approach is totally wrong. To explain I have a class (foo) managed by a shared_ptr and it contains a member class (bar) with needs to access some members of foo. So I figure I need some sort of pointer in the bar class back to the foo class. I thought using a weak_ptr was the obvious choice, here is what I came up with it; using namespace boost; class foo; class bar { public: bar(weak_ptr<foo> f) : foo_(f) {} private: weak_ptr<foo> foo_; }; class foo : public boost::enable_shared_from_this<foo> { public: foo() : bar_(shared_from_this()) {} private: bar bar_; }; But I get a boost::bad_weak_ptr error. Now if I use regular pointers instead of weak_ptr's I can get stuff working except that when I use "bar_(this)" in the initialization list for foo MSVC 7.1 gives me a warning, which I don't like. Is there a more appropriate method I should be using to accomplish this. Kind Regards, Eoin.

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String Algorithm: const_cast warning in 1.33.1
by Roman Neuhauser 30 Apr '06

30 Apr '06

The attached patch silences the warnings below in <boost/algorithm/string/split.hpp> (c++ (GCC) 3.4.4 [FreeBSD] 20050518). roman@dagan ~/codex/argv0 1016:0 > cat test.c++ #include <boost/algorithm/string/split.hpp> int main() { return 0; } roman@dagan ~/codex/argv0 1017:0 > c++ -pedantic -Wall -Wextra -Wcast-qual -Wwrite-strings -Wctor-dtor-privacy -Wfloat-equal -Winline -Woverloaded-virtual -Wredundant-decls -Wsign-compare -I/usr/local/include test.c++ /usr/local/include/boost/range/detail/implementation_help.hpp: In function `Char* boost::range_detail::str_end(Char*) [with Char = char]': /usr/local/include/boost/range/end.hpp:98: instantiated from here /usr/local/include/boost/range/detail/implementation_help.hpp:58: warning: cast from `const char*' to `char*' discards qualifiers from pointer target type /usr/local/include/boost/range/detail/implementation_help.hpp: In function `Char* boost::range_detail::str_end(Char*) [with Char = wchar_t]': /usr/local/include/boost/range/end.hpp:103: instantiated from here /usr/local/include/boost/range/detail/implementation_help.hpp:58: warning: cast from `const wchar_t*' to `wchar_t*' discards qualifiers from pointer target type -- How many Vietnam vets does it take to screw in a light bulb? You don't know, man. You don't KNOW. Cause you weren't THERE. http://bash.org/?255991

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Google Summer of Code -- Call for Participation / Schedule
by Jeff Garland 29 Apr '06

29 Apr '06

All - (cross-posted to the user list so the larger Boost community sees this) Readers of the developer list may have seen that Boost has been accepted as a participating organization. See http://code.google.com/soc/boost/about.html for the initial Boost Summer of Code page. Now for the hard part. We have a fairly tight schedule to get organized on project proposals and student applications: May 1, 2006: - Application period opens for student proposals May 8, 2006: -Student proposals due by 17:00 Pacific Daylight Time If you are interested in mentoring or doing a project please let us know as soon as possible. If you have project ideas, please update: http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?Google_Summe… If you want to mentor or are planning a student application please either post to the list or to the moderators list (see http://www.boost.org/more/moderators.html for details). Thx! Jeff

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I/O bug in date_time
by Thomas Lemaire 29 Apr '06

29 Apr '06

** sorry if double posting, but I have not received my first mail, and also no answers... ** Dear list, I encounter a bug while reading a time_duration object, here is a short test case, the results are obtained with boost 1.33.1, gcc4.0.3 using namespace boost::posix_time; time_duration td1(0,0,0); std::stringstream ss1("14:23:11.345678"); ss1 >> td1; std::cout << td1 << std::endl; // 14:23:11.345678 time_duration td2(0,0,0); std::stringstream ss2("18353:23:11.345678"); ss2 >> td2; std::cout << td2 << std::endl; // 18:53:23 time_duration td3(0,0,0); std::stringstream ss3("318353:23:11.345678"); ss3 >> td3; std::cout << td3 << std::endl; // 00:00:00 If I compile with the flag CPPFLAGS += -DUSE_DATE_TIME_PRE_1_33_FACET_IO this works well. I hope this will help to fix it... -- thomas http://www.laas.fr/~tlemaire

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[BGL] Complexity time of algorithms
by Leandro Melo 29 Apr '06

29 Apr '06

Hi. According to the site, most boost graph algorithms guarantee complexity bounds. For instance, DFS and BFS have complexity time O(V + E), Bellman-Ford has complexity O(VE), etc... As fair as I'm concerned (and from the knowledge I have) the complexity time bounds exposed on the graph web pages (like the ones I described above) are usually the 'best' theoretical values for them that can be found in the literature. However, something is still 'dark' for me. Most of this algorithms achieve this time bounds when implemented in a very specialized manner. Boost graph library is NOT like this, since we know it's a very nice generic library. Boost uses Property Maps for a lot of algorithms. My question is whether or not this property maps affect the complexity bounds. For example: In the original implementation of Bellman-Ford (which achieves O(VE)) weights are attached to edges. In boost's implementation, they're in the form of property maps. Right there, there's a change from a constant time operation (edge->get_weight, for example) to a logarithmic time operation (weight_map[edge], for example). I must say that I didn't take carefull look at the algorithms implementations, but it just seems weird to me that the same complexity bounds can still be achieved with those property maps. Can anyone help understand that? Thanks. -- Leandro Terra C. Melo

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regarding "boost::bad_expression"
by yogendra karki 29 Apr '06

29 Apr '06

hi all i am using boost regex to check the systax of my URLs. if i am giving a long URL then it is giving the following error:- terminate called after throwing an instance of 'boost::bad_expression' what(): Memory exhausted Aborted and the program is aboted. My code is this:- #include<iostream> #include <boost/regex/v4/regex.hpp> bool EvaluateRegex(const std::string regularexp,std::string url){ boost::smatch what; boost::regex exp(regularexp,boost::regex::extended); boost::regex_search(url,what,exp); std::string search=(std::string)what[0]; if(search.length() == url.length()) return true; else return false; } int main() { std::string url; const std::string URLSYNTAXREGEX = "((https?|ftp)://)?(((([a-zA-Z0-9]+-?)?[a-zA-Z0-9]+)+[.]{1}[a-zA-Z0-9]+)+([:]{1}((0[0-7]+)|(0[xX][0-9a-fA-F]+)|([0-9]+))){0,1})([?/][-a-zA-Z0-9+&@#/%?=~_|!:,.; ]*)?"; std::cout<<"enter the URL"<<std::endl; std::cin>>url; if(!EvaluateRegex(URLSYNTAXREGEX,url)) std::cout<<"Malformed URL"<<std::endl; else std::cout<<"Well formed URL"<<std::endl; return 0; } --------------------------------- Love cheap thrills? Enjoy PC-to-Phone calls to 30+ countries for just 2¢/min with Yahoo! Messenger with Voice.

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[program_options] Abort trap by store
by Pascal Vizeli 29 Apr '06

29 Apr '06

Hi, I habe a problem with store(parse_config_file(...), ...); I don't know why... That isn't my first program with program_options but it is my first program with parse_command_line and parse_config_file in one. Here is my code. First I parse the command line, second I parse the config file. Is it a very simple script. With my debuger (gdb and ddd) I can see, that the problem is here: bpo::store(bpo::parse_config_file(conf_file, desc_file), vm); (at the "end" from script). vm is global definiert. The Namspace bpo ist boost::program_options I use the gcc 3.3.5 and I compile static with: /usr/local/lib/libboost_program_options-gcc-1_33_1.a My OS is OpenBSD What I make false? My script is at the end. Sorry for my bad english. I thanks for Help, Dear, Pascal Vizeli [cpp] bpo::variables_map vm_cmd; bpo::options_description desc_file("config file"), desc_cmd("command line"); // Make options descriptions desc_cmd.add_options() ("config,c", bpo::value<std::string>(), "The Config file") ("help,h", "produce help message") ; desc_file.add_options() ("port", bpo::value<int>()->default_value(6667), "IRC Server Port") ("server", bpo::value<char *>(), "IRC Server IP") ("nick", bpo::value<std::string>(), "Bot Nick") ("user", bpo::value<std::string>(), "username hostname servername :realname") ("nickserv", bpo::value<std::string>(), "Nickserv Identify string") ("oper-pw", bpo::value<std::string>(), "Oper Password") ("mode", bpo::value<std::string>(), "Mode for Bot") ("logchan", bpo::value<std::string>(), "A #Chan for logs") ("logchan_status", bpo::value<int>(), "Logchan On or Off") ("invite-chan", bpo::value<int>(), "Invite for logchan?") ("invite-command", bpo::value<std::string>(), "Invite Command") ("re-chan", bpo::value<int>(), "Refresh Channellist until SEC") ("logfile", bpo::value<std::string>(), "File for logs") ("chroot", bpo::value<char *>(), "Set the chroot dir (path)") ; // Parse CMD bpo::store(bpo::parse_command_line(argc, argv, desc_cmd), vm_cmd); bpo::notify(vm_cmd); if(vm_cmd.count("help")){ std::cout << desc_cmd << std::endl; std::cout << desc_file << std::endl; exit(0); } if(!vm_cmd.count("config")){ printo_err("Config file not found! Use --help for Infos"); exit(0); } // Open Config file std::ifstream conf_file(vm_cmd["config"].as<std::string>().c_str()); if(conf_file.is_open()){ // Parse Config file bpo::store(bpo::parse_config_file(conf_file, desc_file), vm); // Here is the false say my debuger bpo::notify(vm); }else{ printo_err("can't open the conf file!"); exit(0); } [/cpp]

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Serialization of adjacency_list
by Anatoli Sakhnik 29 Apr '06

29 Apr '06

Hello! I slightely modified kevin-bacon2.cpp from examples of the BGL. Having tried to serialize the graph g back to the text and print it to stdout, I got a static assertion failure. Is serialization of the adjacency_list fully implemented indeed? Or is it a trouble with boost::serialization? -- Anatoli Sakhnik P.S.: diff kevin-bacon2.old.cpp kevin-bacon2.cpp 18a19 > #include <boost/archive/text_oarchive.hpp> 88a90,91 > archive::text_oarchive oa(std::cout); > oa << g;

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Serialization difficulties
by Joseph Hosteny 29 Apr '06

29 Apr '06

Hi all, I'm a relative newbie at using the serialization libraries, so please go easy on me, but I'm having some troubles which I can't seem to work out. I have a class hierarchy that looks something like this: A -> B -> C -> D There is a corresponding header, and at least one source file, for each of the four classes. The base class, A, contains only methods, but is not a pure virtual class. Class B contains the first set of data members in the chain that must be serialized. Classes C and D contain some more methods and data. All stores/loads will be handled via pointers to instances of class D. Now, the header file for class B contains the following: #include <boost/archive/text_iarchive.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/serialization/access.hpp> #include <boost/serialization/base_object.hpp> Classes B, C and D define the following as public: friend class boost::serialization::access; template<class Archive> void serialize(Archive &ar, const unsigned int version); The serialize methods for classes C and D call the base class implementations of these methods via: ar & boost::serialization::base_object<base_class>(*this); Finally, the source files for classes B, C and D contain: #include <boost/serialization/export.hpp> BOOST_CLASS_EXPORT(class_name); It's not clear to me, though, that I should need the EXPORT macro since all loads/stores are done with the most derived class' pointers. However, when I run this code, I get an exception at oserialization.hpp line 394, which is of type archive_exception::unregistered type. I've looked through a lot of the documentation, but can't seem to find out what I'm doing wrong. I've also tried explicit calls to boost::serialization::void_cast_register<base_class, derived_class> (), but that didn't seem to work either. Since this is being retrofitted to a large design, I tried to distill what I was trying to do into a sample project with just empty classes with the same hierarchy and boot methods/macros. When I do this, everything seems to work fine. Does anyone have any suggestions on what I should look for that may be screwing things up for me? I can send the sample files I used, but since these work, I'm not sure if they will be of much help. Any pointers will be greatly appreciated! Thanks, Joe

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[serialization] Empty save_override for tracking_type, object_id_type etc
by Denis Kuznetsov 29 Apr '06

29 Apr '06

Hi, I want to write my own archive class for reading/writing to some defined binary protocol. I'm deriving my archive class from the binary_oarchive_impl template and overriding save_override functions. As protocol is defined, I don't need any additional info(bytes). So I do smth like this: class fast_binary_oarchive : // don't derive from binary_oarchive !!! public binary_oarchive_impl<fast_binary_oarchive> { typedef fast_binary_oarchive derived_t; #ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS public: #else friend class boost::archive::detail::interface_oarchive<derived_t>; friend class basic_binary_oarchive<derived_t>; friend class basic_binary_oprimitive<derived_t, std::ostream>; friend class boost::archive::save_access; #endif // add base class to the places considered when matching // save function to a specific set of arguments. Note, this didn't // work on my MSVC 7.0 system // using binary_oarchive_impl<derived_t>::load_override; // so we use the sure-fire method below. This failed to work as well template<class T> void save_override(T & t, BOOST_PFTO int){ binary_oarchive_impl<fast_binary_oarchive>::save_override(t, 0); // verify that this program is in fact working by making sure // that arrays are getting passed here BOOST_STATIC_ASSERT(! (boost::is_array<T>::value) ); } // all the functions have emtpy body void save_override(const class_id_optional_type &, int) {} void save_override(const version_type&, int) {} void save_override(const class_id_type&, int) {} void save_override(const class_id_reference_type&, int) {} void save_override(const object_id_type&, int) {} void save_override(const object_reference_type&, int) {} void save_override(const tracking_type&, int) {} void save_override(const class_name_type&, int) {} public: fast_binary_oarchive(std::ostream & os, unsigned flags = no_header | no_codecvt | no_xml_tag_checking | no_tracking) : binary_oarchive_impl<derived_t>(os, flags) {} }; Is this correct? What features of the serialization library will not I be able to use?

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