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[signals2][review] The review of the signals2 library (formerly thread_safe_signals) begins today, Nov 1st
by Stjepan Rajko 22 Feb '09

22 Feb '09

Hello all, The review for the Signals2 library (formerly known as thread_safe_signals) submitted by Frank Mori Hess begins today (Nov 1st) and is scheduled to end on Nov 10th. I would like to thank Franz Alt, Terry Golubiewski, Doug Gregor, Ravikiran Rajagopal and Andrew Webber for making this review possible by committing to reviewing the library. How to submit a review: -------- As usual, EVERYONE is welcome to participate in the review discussions and to submit a review. I strongly encourage participation from reviewers that would examine the library from a purely user standpoint (commenting on the interface and / or the documentation), as well as reviewers that would be willing to look into the details of the implementation (i.e., you don't have to focus on both). Here are some questions you might want to answer in your review (feel free to skip those that don't apply to your analysis): * What is your evaluation of the design? * What is your evaluation of the implementation? * What is your evaluation of the documentation? * What is your evaluation of the potential usefulness of the library? * Did you try to use the library? With what compiler? Did you have any problems? * How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? * Are you knowledgeable about the problem domain? And finally, every review should answer this question: * Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Please submit your review either to the list or privately to me by the end of the review period. If you send me a review privately I will forward it to the list so the review can be discussed. If you would prefer me to forward your review anonymously (with your name removed) please indicate that in your e-mail. If you are a first time reviewer, here is some more information to get you started: * http://www.boost.org/community/reviews.html has more information on the review process * the review officially takes place on both the boost dev and boost-user lists, but typically more of the discussion happens on the boost dev list * if you want to get a feel for past reviews, you can find them in the archives (see http://www.boost.org/community/groups.html) - the past review dates are on the review schedule (http://www.boost.org/community/review_schedule.html) Typically, there is a period of discussion between the reviewers and the author, with official reviews coming in towards the tail end of the review period. About the library: -------- * The library can be downloaded from: http://www.boostpro.com/vault/index.php?&directory=thread_safe_signals (latest version is signals2-2008-10-08.zip) * Documentation is also available online: http://www.comedi.org/projects/signals2/libs/signals2/doc/html/index.html * A synopsis: The Boost.Signals2 library (formerly known as thread_safe_signals) is an implementation of a managed signals and slots system. Signals represent callbacks with multiple targets, and are also called publishers or events in similar systems. Signals are connected to some set of slots, which are callback receivers (also called event targets or subscribers), which are called when the signal is "emitted." Signals and slots are managed, in that signals and slots (or, more properly, objects that occur as part of the slots) can track connections and are capable of automatically disconnecting signal/slot connections when either is destroyed. This enables the user to make signal/slot connections without expending a great effort to manage the lifetimes of those connections with regard to the lifetimes of all objects involved. When signals are connected to multiple slots, there is a question regarding the relationship between the return values of the slots and the return value of the signals. Boost.Signals2 allows the user to specify the manner in which multiple return values are combined. * Relationship to Boost.Signals: This is a thread-safe variant of the original Boost.Signals library. There have been some changes to the interface to support thread-safety, mostly with respect to automatic connection management. The following thread offers some more details on the differences between the two implementations, as well as a plan of a phased replacement of Boost.Signals should Signals2 be accepted: http://tinyurl.com/4sqau3 [nabble] The Signals2 FAQ also covers some differences: http://tinyurl.com/576gl6 Kind regards, Stjepan (review manager)

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Using boost::barrier
by Asheh 22 Feb '09

22 Feb '09

Hi, Having trouble with sleeping N threads while I need to wake them. Since boost contains no sleep/wake functionality I have tried using boost::condition, I have had trouble with this too (it seems to cause locks). Somone mentioned boost::barrier I read about it in the documentation and it appears to function in a way I would require, here is what im looking for: I reach a point in the program where I segment a pieces of data and it needs to be processed in parallel on two threads, the main thread waits for the two worker threads to finish processing then continues on, those two threads (or N threads..) must then go back to sleep until they are needed again. Can anyone provide a good solution, if boost::barrier is what im looking for could you help me describe how Id correctly impliment this? Thanks Ashley. -- View this message in context: http://www.nabble.com/Using-boost%3A%3Abarrier-tp22137821p22137821.html Sent from the Boost - Users mailing list archive at Nabble.com.

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Asio HTTP Server
by Christoph Schreiber 22 Feb '09

22 Feb '09

Hi! I'm looking for a smart way to read HTTP-Post data. Is request_handler::handle_request the right place to do this? Or should I better to use connection::handle_read? Any ideas (or even better, examples) anybody? I'm stuck. Regards, luky

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[gil] get raw data from picture
by Stephan Menzel 22 Feb '09

22 Feb '09

Hi there, is there any way to get the raw YCbCr data out of a gil Image that has been read with jpeg_read_image()? *_memory is private in image.hpp and I'm not sure what it contains anyway. Any ideas? Thanks... Stephan

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[GIL] wrapper for QImage
by Tomas Van Verrewegen 22 Feb '09

22 Feb '09

Hi, I'm planning to write an image manipulation application using Boost.GIL as a backbone and Qt for the interface. Now I was thinking it might be a good idea to write a wrapper around QImage to give GIL direct access to the pixels of a QImage. I've been looking at the code and as far as I can tell I have 2 options: (1) create a new GIL image type that wraps the QImage (2) create a "qimage_pixel_iterator" and use "... interleaved_view(...)" Now my question(s): - Would (2) be enough, or is it necessary to also create (1)? - "QRgb" (Qt's pixel type) is a typedef for "unsigned int", so specialising eg. "template<class Pixel> struct gil::channel_type" for "unsigned int" seems somewhat suboptimal (is it an 8bit RGBA pixel or a 32bit Gray pixel?). Some sort of proxy class might be appropriate? Maybe a gil::pixel<...> subclass?

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Regex win vs. linux
by Adam Kornafeld 22 Feb '09

22 Feb '09

Hi, I'm seeking help for the following problem, using the regex library: the following line of code is meant to assist in parsing urls: boost::regex exp("(?is)(https?)://([^:/?#]+):?(\\d{1,5})?/?([^?#]*)?\ \??([^#]+)?#?(\\w*)"); It runs fine in a linux environment, however if compiled with VC9 on windows, it fails with: First-chance exception at 0x7c812aeb in test.exe: Microsoft C++ exception: boost ::exception_detail ::clone_impl <boost::exception_detail::error_info_injector<boost::regex_error> > at memory location 0x0012f768.. I thought that the expression might be too long, and indeed if I shorten the above line to: boost regex exp("(?is)(https?)://([^:/?#]+):?(\\d{1,5})?/?"); it runs fine on windows as well. Any help on what the cause of this can be, would be appreciated. Regards, ==Adam

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Formatted reports and statistics charts for Boost Unit Test Framework
by Slava Imeshev 22 Feb '09

22 Feb '09

Hi All, I just wanted to let you know that now Parabuild is integrated with Boost Unit Test Framework. It provides formatted reports and statistics charts from test logs generated as a part of Continuous Integration or daily and nightly builds: http://www.viewtier.com/products/parabuild/boost_unit_test_framework.h tm Regards, Slava Imeshev

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[accumulators] help/advise required: Need a container to hold accumulator_set
by dhruva 22 Feb '09

22 Feb '09

Hello, I am writing a wrapper class which gets data over time and has to compute a variety of statistics using boost::accumulators. The accumulator cannot be a variable on the stack (function local variable) as it will go out of scope after the function invocation. I will have to make it a member variable of a class. I will not know the type of calculations to requested at compile time. I therefore need a generic accumulator type as member and add the specific type at runtime. In short, I need a container to hold accumulator_set objects. Different type of accumulator_set objects in the container will perform different calculations. The type of calculation I want to perform will be based on input at runtime. pseudo code: #define MEAN 1 #define MAX 2 class calc { public: setmetric(int metricType) { accumulator_set<double, features<> > *pacc; if (1 == metricType) { pacc = new accumulator_set<double, features <tag::mean> >; } else if(2 == metricType) { pacc = new accumulator_set<double, features <tag::max> >; } m_Vacc.push_back(pacc); } compute(double input) { // I will iterate over the vector, get the accumulator_set objects // acc_obj(input) followed by extract } private: std::vector <accumulator_set<double, features<> > *> m_Vacc; }; If features could be added at runtime, I probably could have solved this problem. Other approach is to have an accumulator_set with all supported features (supported by my application) as dropable. Drop all the unnecessary features based on user input. By adding all supported types, I will get a complete accumulator_set class at compile time and having a container to hold it is straight forward. Any help or advise is really appreciated. I may have raised a lot of basic questions but I am a boost newbie and taking a plunge. -dhruva Cricket on your mind? Visit the ultimate cricket website. Enter http://beta.cricket.yahoo.com

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boost::asio::read_until reads too much!
by Rob Currey 22 Feb '09

22 Feb '09

executing this code: boost::asio::streambuf b; std::cout << "socket.available()=" << socket.available() << std::endl; size_t received = boost::asio::read_until(socket, b, "\r\n"); std::cout << "received=" << received << std::endl; std::cout << "b.size()=" << b.size() << std::endl; std::istream is(&b); std::getline(is, m_token); results in output of: socket.available()=34 received=26 b.size()=34 In my app I need to read the 8 bytes (after the 26) as binary (and hence don't use the streambuf to do so). Yet read_until has already consumed them from the socket and placed them in the streambuf :( Suggestions?

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boost library advice wanted
by Sean Farrow 21 Feb '09

21 Feb '09

Hi: I am in the process of implementing a program that turned commands from voice recognition software in to code that are entered in to an application. there are approximately 200 codes available in this particular sofware I am automating. Wile I could use boost::stringAlgo along with the functions available in the stl there must be a better alternative. To give an idea of howthis would work the user might say: conditional new line, and [l] would be placed in the current document onscreen. the user could say skip 5 lines and [sk5] would be entered. >From this it is clar that: 1. some tokens are voiced by the user but are not needed when analysing the input. e.g lines is used for ease of use but not actually used in the analysis. 2. some tokens are only followed by certain othe tokens, e.g new can be followed by line, page or paragraph. tow queries: 1. What is the best boost library to use in this situation, boost.wav, boost.spirit, boost.xpressive or boost.tokenizer. 2. Has anybody else done anything like this, and hence can offer any implementation advice. Any help apreciated. Sean.

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