October 2008 - Boost-users - lists.preview.boost.org

Re: [Boost-users] [boost-users][serialization] porting to windows ce?
by Bobby Nations 09 Oct '08

09 Oct '08

Ack, I found a spot where I fat-fingered the code at fault when writing the original message. Please replace ::boost::detail::false_t value; With typename ::boost::detail::false_t value; It doesn't seem to make a difference in the actual error messages themselves, but typos are never good. In case anyone asks, I'm trying to compile against the 1.34.1 release using Visual Studio 2005 SP1 to compile the source via the solution and project files found in "boost\libs\serialization\vc7ide". I also have a patch file that has all of my changes if it might help. Granted it's pretty big (~12 meg) because VS2005 upgraded all of the project files, but I can make it available if it would help. Thanks, Bobby Nations

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[multi-index] Segmentation fault during erase
by Joshua Moore-Oliva 09 Oct '08

09 Oct '08

(I am using 64-bit boost 1.33.1, gcc version 4.1.2) I am trying to track down an elusive segmentation fault that occurs after days of running a program. I am wondering if I am using the boost multi-index library incorrectly. I have a coredump that gives the following backtrace (full backtrace at the end of this email). at /usr/include/boost/multi_index/detail/ord_index_node.hpp:274 a274 while(x!=root&&(x==0 || x->color()==black)){ having looked at the code in that function, I can only assume it is called as a result of these two following lines: (Attempting to erase the first member of the index). CallQueue::nth_index<CALL_NEXT_CALL_TIME>::type & timeIndex = this->m_calls.get<CALL_NEXT_CALL_TIME>(); timeIndex.erase( timeIndex.begin() ); I am certain that the queue is not empty, as the following methods guard against an empty queue. (Shown in an excerpt of my relevant code at the bottom of this email). Finally, my definition for the m_calls structure and #defines for the indexes follow at the end of this email. My program is very clean memory wise, having run a fairly extensive test suite through valgrind, so the possibility of other memory errors compounding are low. My main question is if I am using the multi-index library incorrectly, or if there is a bug in the multi-index library. Failing that, any insight as to why I would be getting this error is appreciated :). Thanks, Josh %%%START m_calls structure%%% typedef boost::multi_index::multi_index_container< Call * , boost::multi_index::indexed_by< boost::multi_index::ordered_unique< BOOST_MULTI_INDEX_CONST_MEM_FUN( Call , int , getId ) > , boost::multi_index::ordered_non_unique< BOOST_MULTI_INDEX_CONST_MEM_FUN( Call , const boost::posix_time::ptime & , getNextCallTime ) > > > CallQueue; CallQueue m_calls; %%%END m_calls structure%%% %%%START #defines for m_calls indexes%%% #define CALL_ID 0 #define CALL_NEXT_CALL_TIME 1 %%%END #defines for m_calls indexes%%% %%%START MY CODE%%% Call * PhoneList::getNextCall() { if ( this->m_calls.empty() ) { throw NoAvailableCallException(); } CallQueue::nth_index<CALL_NEXT_CALL_TIME>::type::iterator pos = this->m_calls.get<CALL_NEXT_CALL_TIME>().begin(); return *pos; } Call * PhoneList::popAvailableCall() { Call * c = this->getNextCall(); if ( c->getNextCallTime() > LocalTime::getInst()->getCachedTime() ) { throw NoAvailableCallException(); } CallQueue::nth_index<CALL_NEXT_CALL_TIME>::type & timeIndex = this->m_calls.get<CALL_NEXT_CALL_TIME>(); timeIndex.erase( timeIndex.begin() ); /*************BELIEVED THAT ERROR ORIGINATES HERE****************/ return c; } %%%END MY CODE%%% %%%START GDB BACKTRACE%%% #0 0x000000000044a7fd in Database::AQM::QueueEngine::PhoneList::popAvailableCall (this=<value optimized out>) at /usr/include/boost/multi_index/detail/ord_index_node.hpp:274 a274 while(x!=root&&(x==0 || x->color()==black)){ (gdb) backtrace #0 0x000000000044a7fd in Database::AQM::QueueEngine::PhoneList::popAvailableCall (this=<value optimized out>) at /usr/include/boost/multi_index/detail/ord_index_node.hpp:274 #1 0x000000000044664c in Database::AQM::QueueEngine::Controller::getCall (this=0x6d54d0) at Controller.cpp:83 #2 0x0000000000411d55 in Database::AQM::Controller::getCall (this=<value optimized out>) at Controller.cpp:75 #3 0x000000000041169b in Control::AQM::Controller::getCall (this=<value optimized out>) at Controller.cpp:27 #4 0x000000000040a01b in Boundary::AQM::RequestSocket::Controller::getCall (this=<value optimized out>) at Controller.cpp:43 #5 0x000000000045a703 in Boundary::AQM::RequestSocket::GetCallRequest::perform (this=<value optimized out>) at GetCallRequest.cpp:17 #6 0x0000000000410564 in Boundary::AQM::RequestSocket::RequestSocket::OnLine (this=0x6d31f0, l=@0x6d3340) at RequestSocket.cpp:30 #7 0x0000000000483829 in TcpSocket::ReadLine (this=0x6d31f0) at TcpSocket.cpp:810 #8 0x0000000000480a9c in SocketHandler::Select (this=0x42802b90, tsel=0x42802b70) at SocketHandler.cpp:395 #9 0x0000000000482e25 in SocketHandler::Select (this=0x2aaab04c8b98, sec=<value optimized out>, usec=1297040160) at SocketHandler.cpp:227 #10 0x000000000040ee6b in Boundary::AQM::RequestSocket::RequestPoller::run (this=0x2aaab0000e40) at RequestPoller.cpp:84 #11 0x00002aaaaad15c3f in boost::function0<void, std::allocator<boost::function_base> >::operator() () from /usr/lib64/libboost_thread.so.2 #12 0x00002aaaaad156bf in boost::thread_group::join_all () from /usr/lib64/libboost_thread.so.2 #13 0x0000003aa56062f7 in start_thread () from /lib64/libpthread.so.0 #14 0x0000003aa4ace86d in clone () from /lib64/libc.so.6 #15 0x0000000000000000 in ?? () %%%END GDB BACKTRACE%%%

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Question on boost multi-index container erase method
by Ramesh 09 Oct '08

09 Oct '08

Hello Joaquin, I am trying to erase a record in the container based on keys - in my case both the keys are ordered and unique and I need to have ways to delete records based on either of the keys. I tried to erase an element based on key2 & I got the following error: "error: no matching function for call to 'boost::multi_index ....<Error runs for more than a page> :erase(boost::multi_index::detail::index_iterator <boost::multi_index::detail::ordered_index_node<boost::multi_index::detail ::index_node_base<MyMap> > >&)' The compiler is perhaps complaining that I havent provided a prototype for erase in the map? In my case I wish to erase the record pointed by the iterator (In another class I had a single index and I didnt have the need to provide a prototype, is it because I have two 'unsigned long' keys that the compiler expects a prototype? )- Kindly help me fix this error. My code is posted as below: Thanks /R --- //fwd decl class A; struct MyMap { unsigned long key1; unsigned long key2; A *pObj; MyMap(unsigned long param_key1, unsigned long param_key2, A *param_pObj): key1(param_key1), key2(param_key2), pObj(param_pObj){} ~LCMap(){ key1 = 0; key2 = 0; pObj = 0; } }; struct key1{}; struct key2{}; typedef multi_index_container< MyMap, indexed_by< ordered_unique< tag <key1>, BOOST_MULTI_INDEX_MEMBER(MyMap, unsigned long, key1)>, ordered_unique< tag <key2>, BOOST_MULTI_INDEX_MEMBER(MyMap, unsigned long, key2)> > >tMapDef; class MyWrap { private: MyMap MyContainer; .. public: insert(UINT32, UINT32, A *); erasebykey2(unsigned long); }; bool MyWrap::erasebykey2(unsigned long param_key2) { bool ret = FALSE; typedef tMapDef::index<key2>::type tKey2Type; tKey2Type& key2_index = MyContainer.get<key2>(); tMapDef::index_iterator<key2>::type it = key2_index.find(param_key2); if (it == key2_index.end()) { cout << "No matching Recs with key2" <<endl<<; return FALSE; } tMapDef::size_type status = MyContainer.erase(it); }

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[python] Adding a path to sys.path
by Robert Dailey 08 Oct '08

08 Oct '08

Hi, I was wondering if the code below is correct for adding a path to sys.path in Python. Note that this will occur before any modules have been executed/imported through Boost.Python. I'm also embedding the interpreter, which is why I am doing this. I'm not sure how it can obtain the sys.__dict__ when I haven't imported sys, so explanation on this would be helpful for me. using namespace boost::python; using namespace boost::filesystem; object sys = GetNamespace( "sys" ); list syspath( sys["path"] ); syspath.insert( 0, complete( path ).file_string() ); sys["path"] = syspath; Note that "path" is a boost::filesystem::path object containing the path I wish to add to sys.path.

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The Placeholders _1 and _2
by Missing Rainbow 08 Oct '08

08 Oct '08

Hi All, I am going through Chapter 3 of the MPL book ("A Deeper Look at Metafunctions") and have some questions on the placeholders _1 and _2. They are first introduced in the section 3.1.5 as follows: typename mpl::transform<D1, D2, mpl::minus<_1, _2> >::type I understand from the context that _1 represents D1 and _2 represents D2. From this I understood that _1 will represent the first template argument and _2 will represent the 2nd template argument. This made sense in this context. But later I came across the following in section 3.3: template <class X> struct two_pointers : twice<boost::add_pointer<_1>, X> {}; In this context, it looks like _1 represents X, which is the 2nd template argument. So what exactly _1 and _2 represents? The book doesn't seem to define them. While I haven't completely read the book yet, if it is defined at some other place, it would have been helpful to provide a cross-reference when they are first introduced in chapter 3. Can anybody provide a reference that explains what is a placeholder and what _1 and _2 mean? And what is the maximum number of placeholders? Thank you. Rgds, anna -- Two Party Fraud: Staged Presidential Debates http://missingrainbow.blogspot.com/2008/10/two-party-fraud-staged-president…

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[boost-users][serialization] porting to windows ce?
by Bobby Nations 08 Oct '08

08 Oct '08

All, I've been working to get boost-serialization running on a Windows CE (actually Pocket PC 2003) device these last few days, and have hit a snag. Could anyone help me with what might be causing the following errors in the operators.hpp file? c:\Documents and Settings\388572\Desktop\sandbox\Boost_1_34_1\boost\libs\serialization\vc 7ide\..\..\..\boost/operators.hpp(699) : error C3083: 'detail': the symbol to the left of a '::' must be a type It happens at this section of code: namespace boost { // A type parameter is used instead of a plain bool because Borland's compiler // didn't cope well with the more obvious non-type template parameter. namespace detail { struct true_t {}; struct false_t {}; } // namespace detail // Unspecialized version assumes that most types are not being used for base // class chaining. We specialize for the operator templates defined in this // library. template<class T> struct is_chained_base { ::boost::detail::false_t value; }; The error happens at the '::boost::detail::false_t value' line. So far, I've been surrounding any mentions of the locale header file or it's attendant classes with '#ifndef BOOST_NO_STD_LOCALE ... #endif' blocks, which allowed me to compile about half of the .cpp files. I also added code to use Microsoft's WideCharToMultiByte() and MultiByteToWideChar() methods rather than using the std::wctomb() and std::mbtowc() . Can anyone explain why the above code throws errors? It seems to be te final remaining hurdle to getting this working (well, sort of working anyway). Thanks, Bobby Nations

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[Boost.Bimap] templated Bimaps and tagging; efficiency
by Christoph Duelli 08 Oct '08

08 Oct '08

I'd like to replace a bidirectional mapping (2 std::maps so far) with Boost.Bimap. Being based on Boost.MultiIndex I hope there are some space savings there (also I could not find specifics in the docs). I have run into some questions/issues that I hope someone can shed light upon. i) I insert a name/value pair like: typedef boost::bimap<std::string, int> MyBimap; MyBimap myBimap; bool ok = myBimap.insert( typename MyBimap::value_type(name,val) ).second; Is it possible (w/o checking afterwards) to find out *why* the insert failed? (It might be a duplicate on the left or the right side. I want to print a helpful debug message...) ii) I would like to use a Bimap in a templated class: Works ok. When I try to tag the bimap, I get the following errors (using gcc 4.1.2) error: expected primary-expression before 'template' error: expected `;' before 'template' (The errors are the calls to by<country>() // wrapped tagged_simple_bimap.cpp from the Bimap docs in a template class: template<typename T> class X { typedef bimap < tagged< std::string, country >, tagged< T , place > > results_bimap; ... }; (I have attached the modified example.) Tagging works if the bimap definition does contain templated types. Any ideas what I am doing wrong? iii) I need the order of my insertions at one place in my code. Do I lose lookup efficiency (on the left side) when I declare my map as: typedef bimap <vector_of<std::string>, int> (My (bi)map is initialized once and then used for lookups only. Is it better in that case to store the insertion order in a separate vector? Or should I go for the more awe-inspiring Boost.Multimap if I want a Bimap (with efficient lookup) *and* have access to the insertion order? ) iv) What is the difference between: typedef bimap< std::string, int, list_of_relation> ...; and typedef bimap< vector_of<std::string>, int> ...; Thank you for a helpful library (collection). Christoph

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[filesystem] Problem mixing read and write on io fstream
by Sachin Garg 08 Oct '08

08 Oct '08

I have a program which opens a boost fstream in binary input+output mode, creating the file if it doesn't exists. But writing doesn't works after reading, it must be something obvious that I am not aware of. filename is a wpath. f.open(filename,ios::in | ios::out | ios::binary | ios::trunc) The program flow is 1) write some data 2) read the data 3) overwrite old data //this fails I am aware that mixing reading and writting is complicated due to buffering and as far as I know the solution is to do a seekg or seekp when changing between reading and writting, I am doing this between 1, 2 and 3. In 'my' program, writting in step 3 fails. I wrote a simple program that does just the above 3 steps with seeks and it works but in my program, it sets the failbit. After lots of debugging in internal fstream code I figured that an internal flag _IOREAD gets set somehow in step 2 which indicates that the stream is now readonly and causes subsequent writes to fail. It also seems that _IOREAD is set anytime any read operation is done on a read+write file, is this correct? And now how do I 'unset' this flag? I tried calling f.clear and f.seekp but that doesnt helps. What might be special in my program that causes this read-mode flag to remain set while this doesn't happens in a barebone/simple test program. I am not doing anything except f.seekg, f.get, f.read. Sachin Garg ps. If it matters, I am using visual studio 9.0. Problem might not be boost specific as boost only uses stl fstream but any help will be really useful.

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Re: [Boost-users] [program_options] linker error LNK2005 (symbol already defined in object)
by Andrei LIHU 08 Oct '08

08 Oct '08

I think I had this problem too a long time ago. I fixed that in \include\boost\boost\program_options\variables_map.hpp. Here is the standard Unix diff for that file. 128c128 < friend void store(const basic_parsed_options<char>& options, --- > friend void BOOST_PROGRAM_OPTIONS_DECL store(const basic_parsed_options<char>& options, -- Check if it works this way for you. Kind regards, Andrei LIHU -------------------- C++ Software Developer +40742545392

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Boost Program Options Optional Value (request for implicit_value() behaviour change to allow space)
by Andrei LIHU 08 Oct '08

08 Oct '08

Description of the real problem: - let "-b" be the name of the option - it disables, if not present in command line, the general app logging - it enables, if present in command line, the general app logging in a default chosen logfile - it enables, if present in command line with a string argument, the general app logging into the file specified as string argument Usage example: >> program_name (no logging) >> program_name -b (logging enabled; goes to logfile.log) >> program_name -b "C:\otherlogfile.log" (logs where specified) So far I found a solution based on implicit_value() behaviour, with "-b" of type string, but my main problem is that in this case I am forced to enter the value to be adjacent to "-b" (e.g. -b"C:\otherlogfile.log"). The desired form would be the one with a space between, in order to maintain our backward compatibility of scripts (e.g: -b "C:\otherlogfile.log"). Can you help me with a good solution? (Even solutions that crack into the source of boost program options library are appreciated.) Thank you for your time. -- Kind regards, Andrei LIHU -------------------- softNRG C++ Software Developer +40742545392

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