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Warning c4002 with boost_foreach
by Sean Farrow 05 Sep '08

05 Sep '08

Hi: Could somebody please tell me why I get a warning c4002 with the following boost::foreach declaration? BOOST_FOREACH( boost::bimaps::bimap<boost::bimaps::set_of<std::vector<std::bitset<6>>>, int>::left_reference CurrentSign, SignsList.left ) Should I use a typedef instead? Sean. __________ Information from ESET NOD32 Antivirus, version of virus signature database 3420 (20080905) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com

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[Thread]Deadlock using shared_mutex with unique_lock
by Stanislav Stoyanov 05 Sep '08

05 Sep '08

Hi everyone, I am trying to use shared_mutex with unique_lock but my program blocks. I am using boost 1.35. My compiler is MSVC 8.0.50727.762 and my OS is Windows 2000. Here is a minimal code to reproduce the problem: #include "boost/thread.hpp" #include "boost/thread/shared_mutex.hpp" #include "boost/bind.hpp" class Executor { public: void run() { boost::unique_lock<boost::shared_mutex> lock(theMutex); boost::thread::sleep(boost::get_system_time() + boost::posix_time::millisec(30)); } private: boost::shared_mutex theMutex; }; void main() { Executor ex; boost::thread_group group; for(int i=0; i<200; i++) { group.create_thread(boost::bind(&Executor::run, &ex)); } group.join_all(); } The program blocks during the call of group.join_all(). According to the Boost.Thread documentation, unique_lock<boost::shared_mutex> lock(theMutex) acquires exclusive ownership of theMutex. Therefore, I expect that the behaviour of boost::unique_lock<boost::shared_mutex> lock(theMutex); is the same as if a boost::mutex is used. Is my assumption correct or am I missing something? Thank you for any help you can provide, Stanislav

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Linker error for thread methods
by Marc Riese 05 Sep '08

05 Sep '08

Hi, I'm trying to use the boost::thread library in an own dll with Visual Studio 2003. I'm using boost 1.36.0 and built it myself with bjam according to http://www.boost.org/doc/libs/1_36_0/more/getting_started/windows.html First I tested with a simple example, that I've found somewhere in the documentation: struct thread_alarm { thread_alarm(int secs) : m_secs(secs) { } void operator()() { boost::xtime xt; boost::xtime_get(&xt, boost::TIME_UTC); xt.sec += m_secs; // boost::this_thread::sleep(xt); } int m_secs; }; boost::thread thrd(thread_alarm(1)); This code runs and compiles fine. I can add a loop and some couts in the operator() for example and get the output parallel to my application. But when I uncomment the line boost::this_thread::sleep(xt);, I get the following linker error: error LNK2019: unresolved external symbol "bool __stdcall boost::this_thread::interruptible_wait(void *,struct boost::detail::timeout)" (?interruptible_wait@this_thread@boost@@YG_NPAXUtimeout@detail@2@@Z) referenced in function "void __stdcall boost::this_thread::interruptible_wait(class boost::posix_time::ptime const &)" (?interruptible_wait@this_thread@boost@@YGXABVptime@posix_time@2@@Z) The same occurs for other thread methods like yield(). I assume there's a problem with the calling convention, but using something other than __stdcall is not an option for me, since I have to comply with a given specification. I didn't find any information about calling conventions in the boost documentation. Is there a solution for this, or does the boost::thread library require the __cdecl calling convention? Regards, Marc

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comparing objects using boost
by Reena Dass 05 Sep '08

05 Sep '08

Is there something available to compare objects using boost, similar to java.lang.Object Equals? Reena

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newbie: debugging programs with boost
by p＠dirac.org 05 Sep '08

05 Sep '08

Hi all, I'm having trouble using GDB with my program that uses boost. In GDB (bra is a vector<double>): (gdb) print bra(j) Invalid data type for function to be called. I've compiled my program with -g3. How can I peek at boost datatypes? Thanks!

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[timer] eclapsed return zero
by gmail 05 Sep '08

05 Sep '08

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Purpose of identity template
by Annamalai Gurusami 05 Sep '08

05 Sep '08

Hi All, I have been going through the documentation of the multi_index_container in the Boot.MultiIndex library. In the example code provided I saw the use of the identity<> template. The relevant portion of the example code is reproduced here for convenience. http://www.boost.org/doc/libs/1_36_0/libs/multi_index/doc/index.html typedef multi_index_container< employee, indexed_by< // sort by employee::operator< ordered_unique<identity<employee> >, // sort by less<string> on name ordered_non_unique<member<employee,std::string,&employee::name> > > > employee_set; I am trying to understand what is the use of the identity<> template class. I also noticed the following in the documentation, "The predefined identity predicate can be used here as a key extractor; identity returns as the key the same object passed as argument." Is there any reason why the word object (instead of type) is used in that sentence? Also if the identity<> template evaluates to the type given as its argument, is there any benefit out of it? I am quite new to template meta programming and am trying to understand things. Any explanation would be very helpful. Rgds, anna -- Abusive Language on Internet http://missingrainbow.blogspot.com/2008/08/abusive-language-on-internet.html

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Re: [Boost-users] [boost.serialization How does boost.serialization do with BOM
by Tan, Tom (Shanghai) 05 Sep '08

05 Sep '08

Thanks for the quick response. BOM is Windows specific. In my opinion, BOM is not really related to how you encode the text(thus not related to uft_codecvt_facet), but how you mark what your encoding is; so that any text editor can get a prompt of how to handle the text. It's implemented by inserting a few bytes to the very beginning of the file, which are never used in the chosen encoding of the following code. In the case of UTF-8, "EF BB BF" are used -- in the encoding table of UTF-8, "EF BB BF" should correspond to no character(I did not check, just out of guess). As it's related to general text files, not specific to xml files. basic_text_iarchive might be a better place to address the issue. I am thinking just detecting " EF BB BF " and discarding them if they exist would solve the issue. But I am not sure which method need to be overriden, can you please advise? Thanks, tom >This is news to me. >the wide character text/xml archives use UTF-8. They do this >by creating a stream with the uft_codecvt_facet. I used >this factet, it worked great and I moved on. So you're way >ahead of me on this. >This would probably be easy to address in the xml_iarchive code >or perhaps the xml_grammar - but, as I said, I don't know >anything about it. >Robert Ramey Tan, Tom (Shanghai) wrote: >> what is BOM? > >> Probably "Byte Order Mark", see > http://en.wikipedia.org/wiki/Byte-order_mark > > Yes, That's what I meant. > > I was testing the demo_xml_load.cpp and demo_xml_save.cpp available > in the boost.serialization example. > By simply opening demo_save.xml produced by demo_xml_save.exe with XML > copy editor(http://xml-copy-editor.sourceforge.net/) and saving it > back, demo_xml_load.exe would crash. I compared the two files with > Winmerge. It said it's identical. > > by studying the hex view, I later found it's because the 3-byte UTF-8 > BOM was inserted to the beginning of file. It would not change the > data, and in many cases was ignored by the text editors. > > I thinking that Boost.serialization should also handle this for all > text files including XML. > > Tom ------------------------------ _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users End of Boost-users Digest, Vol 1744, Issue 1 ********************************************

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newbie: initializing a matrix
by Pete 05 Sep '08

05 Sep '08

The examples I've seen construct matrices using for loops, like: matrix<double> m (3, 3); for (unsigned i = 0; i < m.size1 (); ++ i) for (unsigned j = 0; j < m.size2 (); ++ j) m (i, j) = 3 * i + j; but that's inconvenient. I have a matrix in mind, say: double foo[3][3] = { { 1.0, 2.0, 3.0 }, { 2.0, 9.3, 8.1 }, { 3.0, 5.0, 2.3 } }; Is it possible to initialize a matrix<double> from a double[][]? How does one create a matrix without resorting to for loops or via n^2 assignments in the code? Thanks!

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[program_options] Specific sections for options - lack of documentation
by Ken Johnson 05 Sep '08

05 Sep '08

I have absolutely loved the program_options library, and thank those who developed it so well and comprehensive. I love the config file parsing, but am confused on how to implement specific sections. The documentation speaks of parsing through sections of the config file on the following page. Library Overview --> Specific parsers --> Configuration file parser http://www.boost.org/doc/libs/1_36_0/doc/html/program_options/overview.html… However there is no discussion on how to setup some option that is part of a specific section. How can I do this and how will it affect the command line options? I noticed that boost_1_35_0/boost/program_options/detail/config_file.hpp talks about this functionality a little more. I appreciate any help with this, and would especially enjoy code snippets that illustrate creating options that belong to a section.

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