February 2009 - Boost - lists.preview.boost.org

[trac] Type of ticket: "Bugs", "Patches", or "Feature Requests"?
by Niels Dekker - mail address until 2010-10-10 12 Feb '09

12 Feb '09

https://svn.boost.org/trac/boost/newticket has a Type dropdown-list that has "Bugs" as default. When my report has a patch file attached, should I set the Type to "Patches" instead? If fact, the report I have in mind is mainly a performance issue. I would like boost::array::swap to internally call boost::swap, instead of std::swap_ranges, mainly because some C++03 implementations of std::swap_ranges exchange the elements by doing element-wise copy operations, even when there is a custom swap for the element type. The new boost::swap utility takes care of calling the appropriate custom swap, whenever found by argument-dependent lookup (ADL). My report will have a patch. So is the type of such a report considered a "Feature Request", a "Bug", or a "Patch"? Kind regards, Niels -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center

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Re: [boost] [log] Review-ready version in the Vault
by Vladimir.Batov＠wrsa.com.au 12 Feb '09

12 Feb '09

Andrey, Thank you for your contribution. I do not think I'll be participating in trial-runs or review as such. However, I read through the documentation and looked at the interface and I thought I'll give you my first (well, second, I looked at your lib. before) impression. I realize that everyone probably has something to say about logging and such a debate can get hot. So, I want to say beforehand that my reply is merely my impression (not a review or criticism of any kind). Firstly, it certainly seems very rich in features and configurable. That is certainly a huge plus for such a library as logging. However, I was truly overwhelmed by the documentation, the interface and the deployment examples. I seemed to be reading about familiar concepts -- severity levels, sinks, filters, formatters, streams/channels. However, after all that I did not feel an inch closer to actually deploying your library. I consider myself a moderately intelligent person but the seeming complexity felt quite intimidating. Somehow other implementations I read about (J.Torjo's, log4cpp, log4j, a bunch of loggers at SourceForge) went down much easier. Roughly, as a user I'd expect something as straightforward as boost::log log(name); // Create a log boost::log::sink sink = boost::log::sink(file)(stdout)(event_log); // Set up sinks boost::log::formatter fmt = boost::log::formatter(date)(thread_id)(name); // Set up the formatter boost::log channel = log.channel(channel-name); // Create a channel log(sink)(fmt); // Associate sinks and formatting if (log) log << "Hello, main world"; if (channel) channel << "Hello, channel world"; Maybe that's what your interface does. I just did not get that warm and fuzzy easiness/familiarity feeling after reading the docs and looking at the deployment examples. I feel there is a considerable room for improvement here. In particular I was left puzzled how you actually create a log instance (I think in the docs it is boost::src::logger). I'd expect to be able to create a log instance with a name and to be able to retrieve that same instance by the name anywhere in the program. That is, boost::log log1(name); boost::log log2(name); would be referring to the same log instance (pointer semantics). That'd be very liberating. Best, Vladimir.

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Re: [boost] Profiling template instantiations (Steven Watanabe)
by PORKOLAB Zoltan 12 Feb '09

12 Feb '09

Hi Steven, We have created a framework for debugging/profiling template metaprograms in 2006. It might give you a few tips. It works based on the same idea you have. We instrument all template codes, both at the begining and at the end of each template we insert a special piece of code emitting warning messages of a well-defined form. Before instrumentation we create an XML file to remember the template positions in the source file. When we parse the warning, using this information we can reconstruct the instantiation stack knowing the original line numbers, identifiers, etc.. At the end we produce another XML for possible front-ends. The framework uses boost::spirit and boost::wave. We have also implemented and tested a visual studio plug-in. An overview of the whole idea: http://gsd.web.elte.hu/templight/ There is also a GPCE article about the framework, you can find it here: http://portal.acm.org/citation.cfm?id=1173746&coll=portal&dl=ACM&CFID=47731… or here: http://gsd.web.elte.hu/contents/articles/gpce06.pdf You can download both the VS binaries and the source from: http://people.inf.elte.hu/pocok Please feel free to use the code or any of the ideas. For technical question you can find Jozsef: jmihalicza(a)gmail.com or me. Regards, Zoltan

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[TR1] Problems with TR1 include paths with Mingw?
by Richard Webb 12 Feb '09

12 Feb '09

Hi, I've got some code that i've been building with MSVC that uses the TR1 lib by adding the boost/tr1/tr1 dir to the include path, which i'm now trying to build using Mingw/msys. It seems to build ok using the code on the release branch, but using the current trunk i get: d:/Boost/BoostSVN/boost/tr1/detail/config_all.hpp:162:41: error: ../4.3.2/utility: No such file or directory Am i doing something silly, or have the recent changes to the include logic broken something for Mingw? For reference, i'm using the GCC 4.3.2 build from http://www.tdragon.net/recentgcc/ Thanks, Richard Webb -- View this message in context: http://www.nabble.com/-TR1--Problems-with-TR1-include-paths-with-Mingw--tp2… Sent from the Boost - Dev mailing list archive at Nabble.com.

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[any] implement reset for direct constructing (adapt to noncopyable)
by nowake＠fiercewinds.net 12 Feb '09

12 Feb '09

Hi All. I modified boost::any to adapt noncopyable object. The boost::any can use noncopyable object like this: _____________________________________________________________ struct B : boost::noncopyable { B() : v1(), v2() {}; B(unsigned int value1, unsigned int value2) : v1(value1) ,v2(value2) {}; unsigned int v1, v2; }; BOOST_AUTO_TEST_CASE(test02) { any test; //test = B(); // compile error //test.reset<B>(10, 20); // compile error test.reset<B, false>(10, 20); //any test2(test); // throw //any test2; //test2 = test; // throw BOOST_CHECK_EQUAL(any_cast<B&>(test).v1, 10); BOOST_CHECK_EQUAL(any_cast<B&>(test).v2, 20); } _____________________________________________________________________ If you are interested in this, please see #2748 for detail. https://svn.boost.org/trac/boost/ticket/2748 Thanks, Nowake

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Boost 1.38.0 released
by Beman Dawes 12 Feb '09

12 Feb '09

Boost 1.38.0 has been released and is available from SourceForge. See http://sourceforge.net/projects/boost/ This release includes three new libraries: Flyweight, ScopeExit, and Swap. Updated Libraries: Accumulators, Any, Asio, Config, Date_Time, Exception, Filesystem, Graph, Hash, Interprocess, Intrusive, Lexical Cast, Math, Multi-index Containers, Proto, Regex, Thread, TR1, Type Traits, Unordered, and Xpressive. Other Changes: Experimental CMake build system. You can read the full release announcement here: http://www.boost.org/users/news/version_1_38_0 The release managers were Beman Dawes, Daniel James, Eric Niebler, and Rene Rivera. --Beman Dawes

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Is it a bug in old version of boost?
by Bill David 12 Feb '09

12 Feb '09

I have the following code in my application. But I find it causes a serious memory leak with a product we are using. Our application is a plug-in to this product. But we are not sure what's the boost version included by this product. The following is the code (On Windows, the product should be written with Visual Studio 2003/2005): /** * @brief Convert modify time string to time_t for easy internal handling * @param str Modify time string returned by HTTP server, e.g. "Fri, 18 Jul 2008 11:53:14 GMT" * @return Corresponding time_t result */ time_t parseDate(const string& str) { ptime p; stringstream ss(str.c_str()); time_input_facet* timefacet = new time_input_facet("%a, %d %b %Y %H:%M:%S %z"); // will be automatically deleted by related locale object ss.imbue(locale(locale::classic(), timefacet)); ss >> p; tm t = to_tm(p); return mktime(&t); } And we find the problem is caused by time_input_facet* timefacet = new time_input_facet("%a, %d %b %Y %H:%M:%S %z"); ss.imbue(locale(locale::classic(), timefacet)); it seems related memory has not been released by locale or some memory is leaked by time_input_facet. We have tested above code separately with boost 1.35.0, 1.37.0, it's OK. So can anybody tell me if it's any problem in above code? Or is it a bug in old version of boost date_time or MS Visual Studio 2003/2005? Or how can I work around it?

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[parameter] function types as named template parameters?
by Frank Mori Hess 11 Feb '09

11 Feb '09

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Does Boost.Parameter support function types as named template type parameters? I'm trying to write a metafunction which lets you use Boost.Parameter to specify the template types for a boost::signals2::signal using named type parameters, as was suggested during the review. But it doesn't seem to work for the "Signature" function type. I get errors like: /home/fhess/svn/boost/boost/parameter/aux_/arg_list.hpp:264: error: function returning a function /home/fhess/svn/boost/boost/parameter/aux_/arg_list.hpp:270: error: function returning a function /home/fhess/svn/boost/boost/parameter/aux_/arg_list.hpp:352: error: function returning a function /home/fhess/svn/boost/boost/parameter/aux_/arg_list.hpp:359: error: function returning a function /home/fhess/svn/boost/boost/parameter/aux_/arg_list.hpp:365: error: function returning a function I can get it to work if I don't use Boost.Parameter for the "Signature" type, but only use it for the other 6 types. Also, I noticed BOOST_PARAMETER_MAX_ARITY defaults to 5, but signals2::signal has 7 parameters. I can't reliably redefine BOOST_PARAMETER_MAX_ARITY in my library header, since it must be defined before boost/parameter/config.hpp gets included. You can't redefine the arity and then re-include the parameter library headers like you can with Boost.Function. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFJeO/v5vihyNWuA4URAtVIAJ9iHlncV/+QON81+qYYWzmzex3yDACg48Kc 2il7aidDE0Xj7tVUMmZaxLw= =eqjh -----END PGP SIGNATURE-----

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Gauging interest in a thread-safe containers library
by Eric Greveson 11 Feb '09

11 Feb '09

Hi all, I've recently been doing some work that required thread-safe containers (queue, channel) and I found that in addition to these, a locking_ptr with similar semantics to boost::shared_ptr (except being thread-safe too) allowed me to perform all my threaded operations without needing to worry about synchronisation outside the container/locking_ptr code, and without a major impact on performance compared to coding locks in a slightly less generic (== paranoid) way. These have been re-used with some success by others, and a couple of containers (specifically the queue and channel) seem to be used commonly enough to be worthy of an inclusion in Boost.Thread or similar. This discussion has been had in the past, on this thread: http://lists.boost.org/Archives/boost/2004/09/71454.php Someone else mentioned it later, but there doesn't seem to be much else said here: http://lists.boost.org/Archives/boost/2005/11/96991.php I was wondering if there is more interest now, a few years on. Some of the pros I can think of are: * Writing correct thread-safe code can be tricky (I messed up the first time I wrote my queue). * Use of multithreading is perhaps more prevalent now, with many-core CPUs, than it was 4 years ago * Queues / channels in particular are very useful for building threaded pipelines etc, and more people might be tempted to use such programming techniques if a safe option was available "out-of-the-box" * A thread-safe shared pointer provides a lazy but effective way of synchronising data in many scenarios (my implementation supports the usual boost::shared_ptr stuff except for get(), -> and *: dereferencing is provided by calling an acquire() function which returns a scoped_lock object on which you can call * and ->.The destructor of the scoped_lock releases the lock.) * The thread-safe shared pointer means you could use a pop-copy queue without significant overhead (depending on use) * The code length for these class templates on a single platform is actually quite short (a hundred lines of code or so) Some cons: * Need to support all the platforms Boost works on * Not much interest for these containers last time * More code to maintain * Questions about how re-usable a synchronised queue is due to performance worries (I believe this not to be a major problem for a major class of problems - e.g. pipelining fairly long operations, such as in image and video processing) I'm sure I've missed some things, but I'd be interesting in hearing whether there's a positive or negative reaction to this. I'd be happy to contribute code for this - it wouldn't be the fastest possible code, but I believe that robust, lightweight, maintainable code is better than nothing in this case, even if it's not the very best lock-free implementation. Thanks for reading! Eric

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[signals2] post-review rfc before moving to trunk
by Frank Mori Hess 11 Feb '09

11 Feb '09

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi all, I've made some changes to Boost.Signals2 in response to some of the suggestions made during the review. Unless there is are show-stopper objections, I'd like to move Signals2 from the sandbox to the trunk in a week or two. For context, Stjepan Rajko's review summary is here: http://lists.boost.org/boost-announce/2008/11/0211.php The current Signals2 documentation is online here: http://www.comedi.org/projects/signals2/libs/signals2/doc/html/ Here is a summary of most of the changes made since the review: *Added a signals_vs_signals2_benchmark.cpp to the signals2/test subdirectory, and made some optimizations to signal invocation speed. *Made sure all macros were prefixed with BOOST_SIGNALS2_. *Added tests for boost::signals2::mutex and dummy_mutex. *Brought back boost::signals2::trackable class to ease porting of single-threaded code from Boost.Signals. *Deprecated deconstruct_ptr/postconstructible/predestructible in favor of deconstruct, a factory function similar to make_shared, which supports postconstructors and predestructors via ADL, similar to how the sp_accept_owner stuff works in boost smart_ptr trunk. *Expanded FAQ entry on differences between Signals and Signals2 by adding some notes on how to deal with the changes while porting. Changed the faq entry into a section. *Added documentation section on thread-safety which describes how the library uses its mutexes internally. *Added boost::signals2::signal_type metafunction which uses Boost.Parameter to allow named template type parameters for signals. *Added sections to the tutorial on postconstructors, extended slots, and signal_type. *Added examples section to docs, with compilable example programs extracted from tutorial, plus a few new ones. *Added a couple paragraphs to the design rationale section about optional_last_value and the signals2 mutex classes. *Added a small description to the optional_last_value reference page. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFJkzY45vihyNWuA4URAivcAKCSGti3YkLGnzjmTr3EfAeN3FfiUwCg13S4 Jp54J65svUx6MVKNOsW31nU= =U39m -----END PGP SIGNATURE-----

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