October 2013 - Boost-users - lists.preview.boost.org

Boost range iterator pointing to wrong element
by Giorgos Sermaidis 09 Oct '13

09 Oct '13

Hi all, I have a vector<pair<bool, int>> from which I need to read (and possibly write) only the vector elements for which the boolean value of the pair is true. I am using boost range filter and reverse adaptors to do that. However, I noticed that the order of the adaptors, ie whether I use reversed | filtered or filtered | reversed produces different results. In fact, for the latter when I use an iterator to the transformed range to change the boolean value of the pair, then the iterator after the change points to a different vector element. This does not happen when I use reversed | filtered. Below is the code demonstrating the issue. Any ideas as to why this is happening are much appreciated! #include <boost/range/adaptors.hpp> #include <vector> #include <utility> #include <iostream> using namespace boost::adaptors; using container_type = std::vector<std::pair<bool,int>>; struct to_include { bool operator()(const std::pair<bool,int>& x) { return x.first; } }; int main() { container_type container; /* element0: 1, 1 */ /* element1: 1, 2 */ /* element2: 1, 3 */ for(size_t i=0; i!=3; ++i) container.push_back(std::make_pair(true, i+1)); container_type container_cpy = container; /* filter and then reverse */ auto fr = container | filtered(to_include()) | reversed; auto fr_it1 = fr.begin(); auto fr_it2 = std::next(fr_it1); fr_it2->first = false; std::cout << "FILTER AND THEN REVERSE\n"; std::cout << fr_it2->first << " " << fr_it2->second << '\n'; /* prints (1,1) instead of (0,2) */ /* reverse and then filter */ auto rf = container_cpy | reversed | filtered(to_include()); auto rf_it1 = rf.begin(); auto rf_it2 = std::next(rf_it1); rf_it2->first = false; std::cout << "\nREVERSE AND THEN FILTER\n"; std::cout << rf_it2->first << " " << rf_it2->second << '\n'; /* prints (0,2) */ return 0; }

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Serial port example compiles in Makefile, but does not compile under Eclipse
by Ulf Samuelsson 07 Oct '13

07 Oct '13

Running Eclipse 3.7.2 on Ubuntu 12.10 (i386) with Boost 1.49 Trying to get a serial port running with a callback Found: http://www.webalice.it/fede.tft/serial_port/serial_port.html and the source: git clone: git://gitorious.org/serial-port/serial-port.git When I compile a serial port example 4 with g++ I do not get any problems. When I compile exactly the same class from Eclipse I get an error. thread t(boost::bind(&asio::io_service::run, &pimpl->io)); // Offending code ------------------------------------------------------------------ 'boost::bind' is ambiguous ' Candidates are: boost::_bi::bind_t<unsigned int,unsigned int (*)(boost::system::error_code &),boost::_bi::list1<boost::_bi::value<boost::asio::io_service *>>> bind(unsigned int (*)(boost::system::error_code &), boost::asio::io_service *) boost::_bi::bind_t<unsigned int,boost::_mfi::mf0<unsigned int,boost::asio::io_service>,boost::_bi::list1<boost::_bi::value<boost::asio::io_service *>>> bind(unsigned int (boost::asio::io_service::*)(), boost::asio::io_service *) ' AsyncSerial.cpp /nodeserver/src line 102 Semantic Error ------------------------------------------------------------------ pimpl->io is a boost::asio::io_service class AsyncSerialImpl: private boost::noncopyable { public: ... boost::asio::io_service io; ///< Io service object ... }; Someone suggest I declare a pointer to the run function, to resolve the problem, which I tried, but didnt get it right. How do I declare a variable, which can be assigned the io_service::run function? <?> myrun = &boost::asio::io_service::run; Any other ideas? Why compile and link in the makefile and not inside Eclipse? Tried on a Ubuntu 13.04 machine with the same problem. BR Ulf Samuelsson ==================================================================== Part of the code. ------------------------ void AsyncSerial::open(const std::string& devname, unsigned int baud_rate, asio::serial_port_base::parity opt_parity, asio::serial_port_base::character_size opt_csize, asio::serial_port_base::flow_control opt_flow, asio::serial_port_base::stop_bits opt_stop) { if(isOpen()) close(); setErrorStatus(true);//If an exception is thrown, error_ remains true pimpl->port.open(devname); pimpl->port.set_option(asio::serial_port_base::baud_rate(baud_rate)); pimpl->port.set_option(opt_parity); pimpl->port.set_option(opt_csize); pimpl->port.set_option(opt_flow); pimpl->port.set_option(opt_stop); //This gives some work to the io_service before it is started pimpl->io.post(boost::bind(&AsyncSerial::doRead, this)); --------------------------------------------------------------------------------------------------------------------------- thread t(boost::bind(&asio::io_service::run, &pimpl->io)); // Offending code --------------------------------------------------------------------------------------------------------------------------- pimpl->backgroundThread.swap(t); setErrorStatus(false);//If we get here, no error pimpl->open=true; //Port is now open } class AsyncSerialImpl: private boost::noncopyable { public: AsyncSerialImpl(): io(), port(io), backgroundThread(), open(false), error(false) {} boost::asio::io_service io; ///< Io service object boost::asio::serial_port port; ///< Serial port object boost::thread backgroundThread; ///< Thread that runs read/write operations bool open; ///< True if port open bool error; ///< Error flag mutable boost::mutex errorMutex; ///< Mutex for access to error /// Data are queued here before they go in writeBuffer std::vector<char> writeQueue; boost::shared_array<char> writeBuffer; ///< Data being written size_t writeBufferSize; ///< Size of writeBuffer boost::mutex writeQueueMutex; ///< Mutex for access to writeQueue char readBuffer[AsyncSerial::readBufferSize]; ///< data being read /// Read complete callback boost::function<void (const char*, size_t)> callback; };

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Using boost::iostreams::restrict without overconsuming the original stream
by Avi Kivity 07 Oct '13

07 Oct '13

Hi, I amy trying to split an incoming streams into multiple substreams (specifically, an incoming cpio stream into its individual files). After parsing the header in the incoming stream, I have the file size, and can use boost::iostreams::restrict to create a substream containing only the file data, which the user can subsequently consume. However some experiments with filtering_streambuf show that it will consume past the end of the substream. Will the same happen with restrict?

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Boost MSM : Virtual Memory Exhausted: cannot allocate memory
by rahul baruah 06 Oct '13

06 Oct '13

Hello, I am using boost Meta - state machine. I have 19 state which is compiling ok. but whn i incease the number of state transition in Transition table(using internal_transition_table) i get this error: *"Virtual Memory Exhausted: cannot allocate memory"* * * * *Has anyone has face the same problem?? Regards Rahul

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Doc error?
by Larry 06 Oct '13

06 Oct '13

In the doc (1.54.0) for algorithms under C++14, the first code segment under both equal and mismatch, the last line (for equal here) shows std::equal ( seq1.begin (), seq1.end (), seq1.begin (), seq2.end ()); // false ^^^^^^ Shouldn’t that be std::equal ( seq1.begin (), seq1.end (), seq2.begin (), seq2.end ()); // false ^^^^^^ Similar for mismatch. Larry

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spirit::qi and Phoenix placeholder
by Olivier Austina 04 Oct '13

04 Oct '13

I am reading Spirit tutorial, at http://www.boost.org/doc/libs/1_54_0/libs/spirit/doc/html/spirit/qi/tutoria…. I am new to boost. It is not clear to me what the placeholder are and when using them. This is some of them: *Spirit.Qi specific Phoenix placeholders* _1, _2... , _N Nth attribute of p _val The enclosing rule's synthesized attribute. _r1, _r2... , _rN The enclosing rule's Nth inherited attribute. _a, _b... , _j The enclosing rule's local variables (_a refers to the first). _pass Assign false to _pass to force a parser failure. For example in this code : template <typename Iterator>bool parse_numbers(Iterator first, Iterator last, std::vector<double>& v){ using qi::double_; using qi::phrase_parse; using qi::_1; using ascii::space; using phoenix::push_back; using phoenix::ref; bool r = phrase_parse(first, last, // Begin grammar ( *double_[push_back(ref(v), _1)] >> *(',' >> double_[push_back(ref(v), _1)])* ) , // End grammar space); if (first != last) // fail if we did not get a full match return false; return r;} why using _1, (using qi::_1) instead of _2 (using qi::_2). Which parts of boost should I read before reading spirit. Any suggestion is welcome. Thank you. Regards Olivier

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Re: [Boost-users] 1.55.0 beta 1 release candidates available for testing
by Craig Henderson 04 Oct '13

04 Oct '13

On 4 October 2013 07:13, Ovanes Markarian <om_boost(a)keywallet.com> wrote: > Marshall, > > is there any link to what has been added/fixed in the new release. Would > be great to find it out before downloading the software. > See http://www.boost.org/users/history/version_1_55_0.html

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Re: [Boost-users] Boost.Coroutine + objects
by Van Pers 03 Oct '13

03 Oct '13

Nathan Ridge wrote: > You need to refer to member functions as '&Abc::first' rather than > just 'first', and you need to bind the implicit object parameter > to something (likekely 'this'): > bind(&Abc::first, this, _1) > Regards, > Nate Thank you Nathan, this works for me. Regards, Van

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[Exception] Duplicate symbol error when using errinfo_api_function in static library
by Georg Leidinger 03 Oct '13

03 Oct '13

Dear readers, I encountered a problem in my project when using *Boost.Exception* with the predefined types errinfo_xyz in a library project. I have two classes ClassA and ClassB in my library which both throw a boost::exception with errinfo_api_function type in their implementation file (.cpp) These both classes are compiled into a static library with the C/C++-Flags -fvisibility=hidden. Then I have a main.cpp which creates an instance of ClassA and ClassB and links to the library which contains ClassA.o and ClassB.o. When I compile the main.cpp I get the linker error duplicate symbol for the errinfo_api_function object in ClassA.o and ClassB.o. If I remove the visibility=hidden flag, it links without problems. I am not an expert on the compiler flags, but I saw that many libraries use the visibility=hidden flag so I think it would be good, if my lib could also use it. For a better description I will show the sources for my project: ClassA.h ------------------------------------------------------------------------------------------------- #pragma once #include <boost/exception/all.hpp> struct my_errorA : virtual std::exception, virtual boost::exception {}; class ClassA { public: ClassA() {}; virtual ~ClassA() {}; virtual void doSomething(); }; ClassA.cpp ------------------------------------------------------------------------------------------------- #include "ClassA.h" void ClassA::doSomething() { BOOST_THROW_EXCEPTION( my_errorA() << boost::errinfo_api_function("doSomething") ); } ClassB.h ------------------------------------------------------------------------------------------------- #pragma once #include <boost/exception/all.hpp> struct my_errorB : virtual std::exception, virtual boost::exception {}; class ClassB { public: ClassB() {}; virtual ~ ClassB() {}; virtual void doSomething(); }; ClassB.cpp ------------------------------------------------------------------------------------------------- #include "ClassB.h" void ClassB::doSomething() { BOOST_THROW_EXCEPTION( my_errorB() << boost::errinfo_api_function("doSomething") ); } main.cpp ------------------------------------------------------------------------------------------------- #include "ClassA.h" #include "ClassB.h" int main(int argc, const char * argv[]) { ClassA A; ClassB B; return 0; } The Linker output: ----------------------------------------------------------------------------------------------------------------- *Ld /Users/georg/Library/Developer/Xcode/DerivedData/ExceptionTest-dcnvciwqbwqvciaokkjjaqchftll/Build/Products/Debug/ExceptionTest normal i386 cd /Users/georg/work/ExceptionTest setenv MACOSX_DEPLOYMENT_TARGET 10.8 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -arch i386 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk -L/Users/georg/Library/Developer/Xcode/DerivedData/ExceptionTest-dcnvciwqbwqvciaokkjjaqchftll/Build/Products/Debug -F/Users/georg/Library/Developer/Xcode/DerivedData/ExceptionTest-dcnvciwqbwqvciaokkjjaqchftll/Build/Products/Debug -filelist /Users/georg/Library/Developer/Xcode/DerivedData/ExceptionTest-dcnvciwqbwqvciaokkjjaqchftll/Build/Intermediates/ExceptionTest.build/Debug/ExceptionTest.build/Objects-normal/i386/ExceptionTest.LinkFileList -mmacosx-version-min=10.8 /Users/georg/Library/Developer/Xcode/DerivedData/ExceptionTest-dcnvciwqbwqvciaokkjjaqchftll/Build/Products/Debug/libExceptionLib.a -o /Users/georg/Library/Developer/Xcode/DerivedData/ExceptionTest-dcnvciwqbwqvciaokkjjaqchftll/Build/Products/Debug/ExceptionTest duplicate symbol __ZTIPN5boost21errinfo_api_function_E in: /Users/georg/Library/Developer/Xcode/DerivedData/ExceptionTest-dcnvciwqbwqvciaokkjjaqchftll/Build/Products/Debug/libExceptionLib.a(ClassA.o) /Users/georg/Library/Developer/Xcode/DerivedData/ExceptionTest-dcnvciwqbwqvciaokkjjaqchftll/Build/Products/Debug/libExceptionLib.a(ClassB.o) duplicate symbol __ZTSPN5boost21errinfo_api_function_E in: /Users/georg/Library/Developer/Xcode/DerivedData/ExceptionTest-dcnvciwqbwqvciaokkjjaqchftll/Build/Products/Debug/libExceptionLib.a(ClassA.o) /Users/georg/Library/Developer/Xcode/DerivedData/ExceptionTest-dcnvciwqbwqvciaokkjjaqchftll/Build/Products/Debug/libExceptionLib.a(ClassB.o) ld: 2 duplicate symbols for architecture i386 clang: error: linker command failed with exit code 1 (use -v to see invocation)* ----------------------------------------------------------------------------------------------------------------- I hope I described the problem well enough and I hope someone can explain what the problem is? Thank a lot and best regards Georg

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[parameter] named template parameters
by ilya shlyakhter 03 Oct '13

03 Oct '13

Some questions about the Boost.Parameter library: - seems like it hasn't been updated in some time -- is it still supported? - when specifying type constraints for named template parameters, is it possible to specify constraints among several type parameters (the way graph_type is used in section 2.1.5.6.1 of the documentation) - are there any issues in the interaction of Boost.Parameter and template specialization, i.e. how do I specialize the template on the values of some of the named parameters? Thanks, ilya

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