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[BOOST Interprocess] file lock error on MSVC 10
by Claude 24 Mar '11

24 Mar '11

Hi, I'm trying to compile simple program with MSVC++ 10 that use <boost/interprocess/sync/file_lock.hpp> include file (boost version 1.44) But I have a compile error in this file at row 68: C:\Users\Claudio\Desktop\boost_1_44_0\boost/interprocess/sync/file_lock.hpp(68): vedere il riferimento all'istanza del modello di funzione 'boost::interprocess::file_lock &&boost::interprocess::move<boost::interprocess::file_lock&>(T)' in corso di compilazione with [ T=boost::interprocess::file_lock & ] "Impossibile associare un elemento lvalue a un riferimento di rvalue" ("Can not associate a lvalue to a rvalue reference") This program compiles without error on GCC 4.5 (Linux Ubuntu) Why? -- View this message in context: http://boost.2283326.n4.nabble.com/BOOST-Interprocess-file-lock-error-on-MS… Sent from the Boost - Users mailing list archive at Nabble.com.

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Boost gregorian date time from preformated string
by Louis Hoefler 24 Mar '11

24 Mar '11

I use boost 1.46.0 and visual studio 2010. I try to convert a string into a date time object. I found some examples that use stringstreams. Is it possible to convert custom formatted date/time strings into gregorian date objects without using a stringstream? Thank you, Louis

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Re: [Boost-users] Thread Interruption Best Practice
by Dom Driver 24 Mar '11

24 Mar '11

> if I understand your problem you want the thread blocking in select to return? Correct. I need this call to return when: 1) I've got some data waiting to be read. 2) The application is terminating and I want to stop my RX communications thread. The first one is straightforward. I'll investigate the use of pipes as a secondary option. As for 2), from other suggestions, I've gone back to the ASIO library. I read about slushies and brain-freeze, and thought it might be the way to go. However, I think I've managed to fall victim to brainfreeze myself. >From the ASIO example at: http://www.boost.org/doc/libs/1_46_1/doc/html/boost_asio/example/echo/async… This is an asynchronous server similar to what I'm trying to do here. I've got a couple of questions on this, 1) When the server object is created, the call to socket.async_read_from() is made immediately. If there is no data waiting, to be read, this call returns immediately, right? 2) When data does arrive, the handler 'handle_receive_from()' is called. Regardless of whether some bytes are read or not, we eventually call socket.async_read_from() again. This is probably quite fundamental to what I'm misunderstanding, but doesn't this mean I'll be effectively calling socket.async_read_from() from within the handler of a call to socket.async_read_from()? Will I be recursing indefinitely until the application terminates? That doesn't sound right, so I must be missing something very obvious here. Hmmm. Biblical-style ray-of-light guidance appreciated!

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Project using Boost won't build with Xcode 4; complains about "global weak symbols"
by G S 23 Mar '11

23 Mar '11

Hi all. I'm using Boost in an iPhone app as a statically linked lib, and after updating to Xcode 4 the project won't build. It fails with this: *ld: bad codegen, pointer diff in boost::system::error_category:* *:error_category()to global weak symbol vtable for boost::system::error_**categoryfor architecture i386* Happens for both simulator and device, after the same project built fine under previous Xcodes. Anybody have some insight on this and a solution? Thanks! Gavin

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[uBLAS] Matrix creation vs resize
by Ryan 23 Mar '11

23 Mar '11

I need to remove rows from a matrix if it fails a comparison. I have two possible options to remove the matrix rows. Option 1 adds a row to the new matrix for each row from the old matrix that passes the comparison. Option 2 keeps track of the rows from the old matrix that passed the comparison and then creates a new matrix all at once. I'm wondering which option is more efficient or is there a simpler way to achieve the same results? Ryan Option 1 void( matrix<double> const& H, matrix<double> const& P, matrix<double> const& R, vector<double> const& v) { double const rejection_criterion = 2; matrix<double> M = prod(H, matrix<double>(prod(P, trans(H))) + R; matrix<double> result; int matrix_size = 1; for (unsigned i = 0; i < v.size(); ++i) { if ( v[i] * v[i] < rejection_criterion * M(i,i)) { result.resize(matrix_size, H.size2(), true); matrix_row<matrix<double> > oldH (H, i); matrix_row<matrix<double> > newH (result, matrix_size - 1); newH = oldH; matrix_size++; } } } Option 2 void( matrix<double> const& H, matrix<double> const& P, matrix<double> const& R, vector<double> const& v) { double const rejection_criterion = 2; matrix<double> M = prod(H, matrix<double>(prod(P, trans(H))) + R; list<unsigned> goodrows; for (unsigned i = 0; i < v.size(); ++i) { if ( v[i] * v[i] < rejection_criterion * M(i,i)) { goodrows.push_back(i); } } matrix<double> result(goodrows.size(), H.size2()); for ( unsigned i = 0, list<unsigned>::iterator iter = goodrows.begin(); i < result.size1(); ++i, ++iter) { matrix_row<matrix<double> > oldH (H, *iter); matrix_row<matrix<double> > newH (result, i); newH = oldH; } }

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String transformation using string_algo
by Remko Tronçon 23 Mar '11

23 Mar '11

Hi, I want to apply an (un-)escaping transformation on a string (e.g., map "<" to "<", map ">" to "<", ...). I was wondering whether boost string algorithms can provide a good way of doing this or not. I was corsidering find_format, but the problem there is that the finder has to check for occurrence of "<" (by matching a string), but then the formatter needs to check again which of the strings the finder matched ("<", ">") to emit the correct character, which sounds suboptimal. A workaround would be to make the finder always succeed, and let the formatter do the actual check and emit the string if it matches. Is there a better alternative? I also noticed there's a "transform_range_copy", but this isn't documented. thanks! Remko

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any __cxa_demangle / UnDecorateSymbolName in boost ?
by Vial, Florent 23 Mar '11

23 Mar '11

Hi all, i want to retrieve the class name of some std::type_info in my application. is there any function to help me with this within boost ? I looked for it in the boost 1.46.1 code but did not find anything. My problem is that UnDecorateSymbolName is not thread safe under Windows. Thank you in advance, Florent ________________________________ Arnold & Richter Cine Technik GmbH & Co. Betriebs KG Sitz: München - Registergericht: Amtsgericht München - Handelsregisternummer: HRA 57918 Persönlich haftender Gesellschafter: Arnold & Richter Cine Technik GmbH Sitz: München - Registergericht: Amtsgericht München - Handelsregisternummer: HRB 54477 Geschäftsführer: Franz Kraus; Dr. Martin Prillmann [http://www.arri.de/fileadmin/mail_images/CTBanner.gif] A new star is born – ALEXA the most versatile digital camera system. Get all the latest information from arridigital.com and YouTube.

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Traversing a graph
by Vipin Varma 23 Mar '11

23 Mar '11

Hi, I have a quick question about graph traversal: what is the appropriate algorithm to be used if I want to find the shortest distance between 2 specified vertices {v_s, v_d} such that every edge on the graph is traversed at least once? I've already used the breadth_first_search() and dijkstras_shortest_paths() for other problems wherein v_s = v_d. Seemingly, these algorithms cannot be used when the source and destination vertices are dissimilar. Thanks, Vipin

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serialization example
by Marco Piacentini 23 Mar '11

23 Mar '11

Hi guys..a very simple question... In the example of the serialization, before serialize, an header is linked to the data. It will be handle both in write and read operations. Is this header essential for the serialization process, or it can be omitted and I can serialize only the data? thank you...

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issues when using boost.bind from boost.thread
by Sean Farrow 23 Mar '11

23 Mar '11

Hi: I'm trying to use boost.bind when starting a thread. The following code starts a thread and tries to pass in a boost.asio.io_service as well. boost::thread* t = new boost::thread(boost::bind(&boost::asio::io_service::run, &io)); I'm getting the following exception when running this code. Unhandled exception at 0x7c812afb in MDRLite.exe: Microsoft C++ exception: boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::system::system_error> > Removing the previous block of code removes the error. Having read the boost.bind, The boost.tread/boost.asio documentation I carn't seem to find what is wrong. This seems to be the final piece of the jigsaw that I carn't seem to crack! Any help appreciated. Cheers Sean.

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