February 2011 - Boost-users

UPDATE rules
by spamjunk 21 Feb '11

21 Feb '11

Is seems that the UPDATE rule for BJAM was changed for 3.1.18. Now, if no targets are defined on the command line, UPDATE defaults to "all". See line #452 of jam.c. This is annoying. I don't want my default to be all, but there is no way (that I know of) the distinguish between an explicit "all" on the command line, and the new defaulted, implicit one. Anyone know of a workaround (outside of changing the code or using an older version)? Thanks.

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[ICL] lower(interval_set) doesn't compile
by John Reid 21 Feb '11

21 Feb '11

I'm not sure if I'm getting the wrong end of the stick from the docs or perhaps I should raise this sort of thing as a bug report? #include <boost/icl/interval_set.hpp> namespace icl = ::boost::icl; void interval_set_intersects() { icl::lower( icl::interval_set< int >() ); } gives: In file included from /home/john/Dev/ThirdParty/boost/boost-trunk/boost/icl/associative_interval_container.hpp:16, from /home/john/Dev/ThirdParty/boost/boost-trunk/boost/icl/interval_base_set.hpp:24, from /home/john/Dev/ThirdParty/boost/boost-trunk/boost/icl/interval_set.hpp:14, from src/sandbox.cpp:2: /home/john/Dev/ThirdParty/boost/boost-trunk/boost/icl/concept/interval_associator.hpp: In function ‘boost::enable_if< boost::icl::is_interval_container<boost::icl::interval_set<int, less, boost::icl::discrete_interval<int, less>, allocator> >, boost::icl::interval_set< int, less, boost::icl::discrete_interval<int, less>, allocator>::interval_type >::type boost::icl::lower(const boost::icl::interval_set<int, less, boost::icl::discrete_interval<int, less>, allocator> &)’: src/sandbox.cpp:6: instantiated from here /home/john/Dev/ThirdParty/boost/boost-trunk/boost/icl/concept/interval_associator.hpp:229: error: no match for ternary ‘operator?:’ in ‘boost::icl::is_empty( ( (const boost::icl::interval_set<int, less, boost::icl::discrete_interval<int, less>, allocator> &)( (const boost::icl::interval_set<int, less, boost::icl::discrete_interval<int, less>, allocator> *)object))) ? boost::icl::identity_element< boost::icl::interval_set<int, less, boost::icl::discrete_interval<int, less>, allocator> >::value() : boost::icl::lower( ( (const boost::icl::discrete_interval<int, less> &)( ( const boost::icl::discrete_interval<int, less> * )boost::icl::key_value( ( (const boost::icl::interval_set<int, less, boost::icl::discrete_interval<int, less>, allocator> *)object )->boost::icl::interval_set<int, less, boost::icl::discrete_interval<int, less>, allocator>::< anonymous >.boost::icl::interval_base_set< boost::icl::interval_set<int, less, boost::icl::discrete_interval<int, less>, allocator>, int, less, boost::icl::discrete_interval<int, less>, allocator>::begin()))))’ using boost SVN version 68955 and gcc 4.4.3

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[boost.signals2] queries
by Sean Farrow 21 Feb '11

21 Feb '11

Hi: I am looking in to using boost.signals2 for a project I'm involved in, but have a few queries: Firstly, if I create a global signall: boost::signals2::signal<void ()> sig; and then a structure: struct DoWork { void operator()() const { //work. } If I then create a private member of a class: DoWork work; And then do: Sig.connect(Work); Will the connection happen on the thread in which the work member variable was defined or will a second thread be utilized? Also given that sig will be a global and hence accessed from multiple threads, do I need a mutex? Cheers Sean.

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Timing out when writing to serial port while still receiving data
by Goetz, Russ 21 Feb '11

21 Feb '11

I've created a wrapper class around boost asio's serial_port class: class SerialPort { public: void open(); void send(const std::vector<uint8> &data); void close(); private: void _startReceiving(); boost::asio::serial_port m_serialPort; boost::asio::io_service m_ioService; std::vector<uint8> m_recvBuf; }; The SerialPort class has an 'open' member function that opens the port and begins waiting for data to be received on the serial port. There's also a 'send' member function that writes the specified data to the serial port. Below is the code (running on a separate thread) that waits for data to be received on the serial port: Receive Thread -------------- while (m_recvData) { m_serialPort.async_read_some(boost::asio::buffer(m_recvBuf), boost::bind(&SerialPort::_recvHandler, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); m_ioService.run(); m_ioService.reset(); } The problem I'm experiencing is that when the flow control of the serial port is set to RTS/CTS, and I try and write to the serial port with the cable unplugged or the CTS serial line otherwise low, the call is a blocking call. I realize this is the way it's supposed to work, but I need to make writing to the serial port timeout after a few hundred milliseconds instead of blocking until CTS goes high. So I found code on the boost user's mailing list to do just that (m_writeDoneEvent is a manual reset event): Write Thread ------------ boost::optional<boost::system::error_code> timerResult; boost::asio::deadline_timer writeTimer(m_ioService); writeTimer.expires_from_now(milliseconds(100)); writeTimer.async_wait(boost::bind(&SerialPort::_writeDone, this, &timerResult, (std::size_t*)NULLPTR, _1, 0)); boost::optional<boost::system::error_code> writeResult; std::size_t bytesWritten; boost::asio::async_write(m_serialPort, boost::asio::buffer(data, length), boost::bind(&SerialPort::_writeDone, this, &writeResult, &bytesWritten, _1, _2)); // Wait for the write to finish, either due to success or timing out. m_writeDoneEvent.wait(); m_writeDoneEvent.unset(); if (writeResult) { // Write completed successfully. writeTimer.cancel(); if (writeResult->value()) { std::ostringstream oss; oss << "Failed to send some or all of the data to " << m_portName << ". Successfully sent " << bytesWritten << " of a possible " << length << " bytes."; throw SerialException(oss.str(), writeResult->value()); } } else if (timerResult) { // Write timed out. Cancel all asynchronous operations (including the // asynchronous call to read). m_serialPort.cancel(); // <==== ***Throws exception*** std::ostringstream oss; oss << "Sending to " << m_portName << " timed out."; throw SerialException(oss.str()); } void SerialPort::_writeDone(boost::optional<boost::system::error_code> *errorToSet, std::size_t *bytesWrittenToSet, const boost::system::error_code &error, std::size_t bytesWritten) const { if (error != boost::asio::error::operation_aborted) { // Set the error code so the caller knows why the asynchronous write //operation finished. errorToSet->reset(error); if (bytesWrittenToSet != NULLPTR) { *bytesWrittenToSet = bytesWritten; } // Signal to the caller that the write operation is complete. m_writeDoneEvent.set(); } } However, when the write operation on the serial port times out, the call to m_serialPort.cancel() above throws an exception, saying 'The attempted operation is not supported for the type of object referenced'. Looking at the source code, the comment where the exception is thrown says that it's an unsafe operation to call cancel on the IO service from a thread when work has been given to the IO service from a different thread. This obviously fits my case - I've submitted an async_read on the Receive thread and I'm trying to cancel all asynchronous work on the Write thread. Is it possible to have a thread always running that's waiting for data to be received on the serial port as well as have a write thread that timeouts? If so, where did I go wrong above? Thanks, Russ

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[boost.asio] issues with io_service.run
by Sean Farrow 21 Feb '11

21 Feb '11

Hi: Ok, I'm trying to use boost::asio::io_service::run as follows. At the top of a .hpp file I have: typedef boost::asio::io_service FolderMonitoringService; I can pass this to a constructor requiring an io_service as follows: boost::asio::dir_monitor dm(FolderMonitoringService); however when I try to do: FolderMonitoringService.run(); I get 2 c2143 errors. 1>d:\work\access for everyone\sibelius access\sibeliusaccessserver\utility.cpp(127): error C2143: syntax error : missing ';' before '.' 1>d:\work\access for everyone\sibelius access\sibeliusaccessserver\utility.cpp(127): error C2143: syntax error : missing ';' before '.' If I remove the typedef previously shown, this line: FolderMonitoringService.run(); Compiles fine, but the line: boost::asio::dir_monitor dm(FolderMonitoringService); will not compile giving c2061, solved with the typedef-thanks igor! I've tried boost.ref, with know success. The function signature of the dir_monitor's constructor is: explicit basic_dir_monitor(boost::asio::io_service &io_service) Dir_Monitor is typedef'd to be basic_dir_monitor. Can anybody please tell me why the run function is causing an issue and how to fix this issue. Regards Sean.

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[Fusion] Adapting template nested structure
by Kamil Renczewski 20 Feb '11

20 Feb '11

Hello I have a compilation error when using BOOST_FUSION_ADAPT_TPL_STRUCT on nested structure. namespace nsp { template< class T > struct Outer { struct Inner { int mint; }; }; } BOOST_FUSION_ADAPT_TPL_STRUCT( (T), (nsp::Outer::Inner) (T), (int, mint) ) Above code generates compiler errors on g++ 4.4.5. Am I doing something wrong? Or maybe BOOST_FUSION_ADAPT_TPL_STRUCT can't adapt nested structures? If so, how can I workaround this? -- best regards Kamil Renczewski

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Adding a new file parsing library
by Dhaivat Pandya 20 Feb '11

20 Feb '11

Hello everyone. I've been using boost in my own projects for about 1 year now, and very often I've noticed that Boost does not have much file parsing support (I may be wrong as of now, please correct me). So, I was wondering if the community would be interested in a creation of a new library that uses the Boost::Filesystem set for cross platform file reading, and parses files for CSV, XML, HTML, etc. and tidies up the above if needed (much like the BeautifulSoup module for Python). Please tell me your views Dhaivat

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Re: [Boost-users] Boost::Asio on ARMV5TE
by Peter Meyer 20 Feb '11

20 Feb '11

Hi, after some debugging and testing i track down the problem to epoll. I don't known if it is a wrong usage by boost::asio or a bug inside the kernel. I've changed epoll_reactor.ipp with some debugging output and a memset. 226 void epoll_reactor::run(bool block, op_queue& ops) ... 239 epoll_event events[128]; 240+ ::memset(events, 0XEE, sizeof(events)); 241 int num_events = epoll_wait(epoll_fd_, events, 128, timeout); In case there are more events then one reported by epoll_wait, only the first epoll_event structure is filled with information. All following structures includes garbage or 0xEE set by memset befor calling epoll_wait. Debug output: Count events: 2 ---------------------------------------- EPOLL[0].data.ptr = 0x1ce8b0 EPOLL[1].data.ptr = 0xeeeeeeee So a workaround is to set maxevents to one. Like this: 226 void epoll_reactor::run(bool block, op_queue& ops) ... 240 int num_events = epoll_wait(epoll_fd_, events, 1, timeout); Is there a known bug about epoll on ARM? Or had boost::asio a bug? With best regards Peter > -----Original Message----- > From: Peter Meyer [mailto:r...@xmail.net] > Sent: Friday, February 11, 2011 7:57 AM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] Boost::Asio on ARMV5TE > > > Hi, > > i've wrote a litte proxy using boost::asio (boost 1.45). Program runs > well on Intel (Linux kernel 2.6.35.10 and gcc 4.5.1). > Same code cross compiled for ARMV5TE (Linux 2.6.24.4 and GCC 4.1.2 or > GCC 3.4.3) crashes always at the same point. > Stacktrace looks like this > > Program terminated with signal 11, Segmentation fault. > #0 0x400e3e20 in ?? () > (gdb) backtrace > #0 0x400e3e20 in ?? () > #1 0x0001cfb0 in boost::asio::detail::posix_mutex::lock (this=0x7d) at > /usr/armv5tel-redhat-linux-gnueabi/sys-root/usr/local/include/boost/asio > /detail/posix_mutex.hpp:52 > #2 0x0001cfe6 in scoped_lock (this=0xbe8a98d0, m=@0x7d) at > /usr/armv5tel-redhat-linux-gnueabi/sys-root/usr/local/include/boost/asio > /detail/scoped_lock.hpp:36 > #3 0x00069bf4 in boost::asio::detail::epoll_reactor::run > (this=0x191538, block=true, ops=@0xbe8a994c) > at > /usr/armv5tel-redhat-linux-gnueabi/sys-root/usr/local/include/boost/asio > /detail/impl/epoll_reactor.ipp:275 > #4 0x0006a06c in boost::asio::detail::task_io_service::do_one > (this=0x1914e0, lock=@0xbe8a99d4, this_idle_thread=0xbe8a9990) > at > /usr/armv5tel-redhat-linux-gnueabi/sys-root/usr/local/include/boost/asio > /detail/impl/task_io_service.ipp:264 > #5 0x0006a33c in boost::asio::detail::task_io_service::run > (this=0x1914e0, ec=@0xbe8a9a0c) > at > /usr/armv5tel-redhat-linux-gnueabi/sys-root/usr/local/include/boost/asio > /detail/impl/task_io_service.ipp:130 > #6 0x0006a426 in boost::asio::io_service::run (this=0xbe8a9bc4) at > /usr/armv5tel-redhat-linux-gnueabi/sys-root/usr/local/include/boost/asio > /impl/io_service.ipp:57 > #7 0x00073504 in proxy::Server::run (this=0xbe8a9bb4) at server.cpp:71 > #8 0x0004e2a4 in main (argc=3, argv=0xbe8a9da4) at proxy.cpp:111 > > It looks like the internal epoll_events data structure > (descriptior_state) is corrupted. > > Any advice is welcome. > > With best regards > Peter > ------------------------------------------------------------------------------------

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[boost.asio] passing a boost::asio::io_service in to a constructure
by Sean Farrow 19 Feb '11

19 Feb '11

Hi: I'm new to working with asio, and have the following currently as two global variables: boost::asio::io_service FolderMonitoringService; boost::asio::dir_monitor dm(FolderMonitoringService); This works fine, but what I'd like to do is to make both variables private. When I do that, I get an error c2061 syntax error on the second line, in visual studio 2010. How can I pass a non-copyable class in to a constructor? Cheers Sean.

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BGL: half-edge-diagram or doubly-connected-edge-list
by Anders Wallin 19 Feb '11

19 Feb '11

Hi group, I want to work with meshes that contain vertices, edges, and faces(1)(2). I've subclassed adjacency_list and added a std::vector to contain the face-data: http://pastebin.com/h4jxpDkt Is there a better solution? (somewhere in the BGL docs it says sublcassing BGL-graphs can be dangerous?) How do I provide a graph_traits::face_descriptor for my sublcass? (now I am using "unsigned int" for face descriptors) How do I allow choice between a vector and a list for storing the vertices? I have also made my first ever attempt (3) to write some template-based code which manipulates this graph class. That file has lots and lots of "typedef" "typename" and "graph_traits" in it. Are there some macros or tools to simplify this style of programming I should be aware of? thanks, Anders (1) http://en.wikipedia.org/wiki/Doubly-connected_edge_list (2) http://www.youtube.com/watch?v=5Rd-u5n0pQs (3) http://code.google.com/p/opencamlib/source/browse/trunk/src/algo/halfedgedi…

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