April 2010 - Boost - lists.boost.org

[gsoc] heaps & queues
by Tim Blechmann 06 May '10

06 May '10

hi all, i'm the student, working on the heaps&queues project during this year's summer of code. i have also been in touch with my mentor about this, but thought, it may be a good idea to hear some comments from other boost devs. i would like to implement the priority queue data as intrusive data structures, which can simply be wrapped to non-intrusive ones. the main reason for this approach is the mutable property. in order to provide a mutable priority queue, one would either need a handle to the inner node (like in dietmar kuehl's pri_queue) or provide a lookup table (as in boost/pending/mutable_queue). both approaches are somehow problematic. otoh, if i want to change the priority of a node, it would be natural to use an intrusive data structure for this. the non-intrusive version would be simply a wrapped version of the intrusive implementation, and would simply lack the mutable property. the question then would be, whether i should try to introduce it into boost.intrusive, or implement it as a library on its own. boost.intrusive already provides a treap, so it would be quite logical to include heap data structures as well. otoh, having a heap library with both intrusive and non- intrusive data structures, one would have everything in one place. so, i see benefits in both approaches, but would like to hear, what other people think about it ... cheers, tim -- tim(a)klingt.org http://tim.klingt.org The first question I ask myself when something doesn't seem to be beautiful is why do I think it's not beautiful. And very shortly you discover that there is no reason. John Cage.

2 3

[release][1.43] Release notes and some other things
by Daniel James 06 May '10

06 May '10

Hello all, Please can you add your release notes for 1.43. If you can't, or don't know how, then just send them to me and I'll do it for you. Sorry I'm late asking this time round. If you didn't realise, you don't have to wait for me to ask, I create the file for the release notes at the beginning of the release cycle. Also, if haven't done so already, can you check the inspect report for your library. It's not too late to fix simple inspect errors (eg. missing newlines, tabs, licenses, broken links) although it is too late to change any code (unless it's an actual bug, of course). You can find links to it on the testing page (http://www.boost.org/development/testing.html) And finally, can you have a look at your library's documentation on the beta site and let me know if it's messed up, as I've been tweaking the way the documentation is displayed. It's still displaying the 1.42 documentation, we only update that after the release. thanks, Daniel

7 12

[Bind] Interoperability of bind/mem_fn with transform_iterator
by Samuel Debionne 05 May '10

05 May '10

Hello all, I'm scratching my head about the correct way to use transform_iterator with bind and mem_fn. In brief, bind and mem_fn return object functions that are not Default Constructible, which means that, when used to construct a transform_iterator, the resulting transform_iterator is not even a Trivial Iterator. Most of the case, it's not a problem because the transform_iterator is never default constructed... until some libs that do concept checking on their template parameters are used. See the following code for exemple : #include <vector> #include <boost/bind.hpp> #include <boost/iterator/transform_iterator.hpp> #include <boost/iterator/iterator_concepts.hpp> #include <boost/concept/requires.hpp> struct foo { size_t id_; size_t get_id() const {return id_;} }; template <class ForwardIterator> void check(ForwardIterator _it) { using namespace boost; function_requires< boost_concepts::ForwardTraversalConcept<ForwardIterator> >(); } int main(int argc, char* argv[]) { using namespace boost; std::vector<foo> foo_vec; //Fail to compile since mem_fn is not Default Constructible check(make_transform_iterator( foo_vec.begin(), mem_fn(&foo::get_id))); //Fail to compile since mem_fn is not Default Constructible check(make_transform_iterator( foo_vec.begin(), mem_fn(&foo::id_))); return 0; } What would be the best way to handle the "problem" ? Patch the bind library to add some default constructors ? Best Regards, Samuel

5 13

[GSoC] Helping out Phoenix v3
by Joel Falcou 04 May '10

04 May '10

Joel and I pondered about getting a student from GSoC to help us complete the phoenix v3 port to proto. I currently have a few prototypes and ideas to extend it further but a few more hands are most welcome. Considering the schedule, I'll be compeltely free for mentoring this prospective student. Now, is it realistic and on topic for GSoC ?

9 33

boost atomic question
by Janek Kozicki 04 May '10

04 May '10

Hello Helge, What would it take to get this code to work? std::vector<boost::atomic<Something> > v; v.resize(100); best regards -- Janek Kozicki http://janek.kozicki.pl/ |

6 12

[GSoC] Bonding period
by Andrew Sutton 04 May '10

04 May '10

Hi All, If your proposal was accepted for GSoC 2010, then you will need to read this email thoroughly since it outlines the basic instructions for getting started with Boost development and your Summer Work. There are a couple of things you'll have to do (detailed instructions follow). 1. Introduce yourself to your mentor 2. Request SVN sandbox access from the Boost owners 3. Get started with Boost 4. Read about bjam and Quickbook 5. Write Code = Detailed instructions = == Introducing Yourself == Send an email to your mentor from the account that you want to receive Boost GSoC-related communications from. We're collecting your contact information in case we need to get in touch. If you have other secondary email address', please forward those also. There may be some organizational overhead to interacting with your mentor. We are still determining the best way to manage some aspects of this process. == Requesting SVN Access == Email the boost owner mailing list and request SVN *sandbox* write access for your GSoC project. Be sure to state that you are a student working on a GSoC 2010 project. Detailed instructions are given here [1] under "Getting a Trac SVN Userid". Your work will ultimately be hosted in this URL [2]. * Note to owners: if you want to validate students you can email me or I can grant you access to the GSoC webapp. == Getting Started == Read this [3] carefully, and follow the instructions. If you want to build Boost's trunk, follow the instructions here [4]. == Bjam and Quickbook == Bjam is the build tool used to compile Boost libraries, test suites, examples, and applications. For information on writing Bjam project files, read the manual, here [5]. Quickbook is the preferred* tool used to document the Boost libraries. It is a frontend to the BoostBook XML schema, which is an extension of the DocBook schema. The documentation toolchain is used to build online and PDF documentation for the Boost libraries. Documentation for writing Quickbook files can be found here [6]. * I could be wrong, but it is popular and also quite nice. == Writing Code == I would suggest trying to build (and document) some small example programs using the Boost development environment before diving in to your project. For example, port some of your programming assignments to Boost -- just don't commit them to the SVN repository :) This will help familiarize you with the Boost infrastructure. Also, read the Boost Guidelines and Requirements [7] before starting your project. These determine the layout of your directory structuring, how to name your files, and basic styles used throughout the Boost C++ Libraries. Additional information on techniques for generic programming can also be found here [8]. These techniques are used throughout many Boost libraries and are definitely worth reading about and understanding. I think that's about it for now. If I missed something, hopefully one of the other contributors will be able to point it out :) Welcome to Boost, and good luck on your summer projects! Andrew Sutton andrew.n.sutton(a)gmail.com [1] https://svn.boost.org/trac/boost/#GettingaTracSVNUserid [2] http://svn.boost.org/svn/boost/sandbox/SOC/2010/ [3] http://www.boost.org/doc/libs/1_42_0/more/getting_started/index.html [4] https://svn.boost.org/trac/boost/wiki/BoostSubversion [5] http://www.boost.org/doc/tools/build/doc/html/index.html [6] http://www.boost.org/doc/libs/1_42_0/doc/html/quickbook.html [7] http://www.boost.org/development/requirements.html [8] http://www.boost.org/community/generic_programming.html

7 16

Re: [boost] [repost][multiarray] Bug with boost::detail::multi_array::array_iterator on MSVC 2010RC?
by Thomas Klimpel 04 May '10

04 May '10

Jesse Perla wrote: > I have attached my test files. Any ideas or patches would be appreciated I could reproduce the problem with MSVC 2010beta2. I noticed that only the debug version fails to build. So I added the line #define _HAS_ITERATOR_DEBUGGING 0 and everything compiled fine. So the simplest solution is to add ADD_DEFINITIONS(-D_HAS_ITERATOR_DEBUGGING=0) to your CMakeLists.txt, which many people recommend in any case, because they claim that the debug version under MSVC would otherwise violate the "runtime complexity specifications" of the corresponding containers and iterators. (I don't know whether this is really true, but I really think that this workaround is not unreasonable.) But of course, you want to know whether this is a bug in boost::multi_array or a bug in MSVC 2010beta2. Before we come to that, another "workaround" would be to change multi_array/iterator.hpp:56 for , boost::random_access_traversal_tag to , std::random_access_iterator_tag This will most probably work, but would lying to the standard library, because the reference reference type of the corresponding iterator is not value_type& (but a proxy): http://lists.boost.org/boost-users/2006/11/23565.php What effectively happens it that the iterator gets the category "input_iterator", but std::copy wants to have an "output_iterator". I think I understand why the iterator doesn't satisfies the requirement of a "forward_iterator", but it's unclear to me why it didn't qualify as an "output_iterator". There is an "input_output_iterator_tag" in "boost/iterator/detail/facade_iterator_category.hpp", so it would have been possible for the iterator to be both "input_iterator" and "output_iterator". However, it seems to me that "input_output_iterator_tag" is never used in the Boost.Iterator library. I would have to read more about "output_iterator" to understand whether Boost.Iterator is correct here. With my current understanding of "output_iterator", I would say it's a bug in "boost/iterator/detail/facade_iterator_category.hpp". Perhaps somebody with more knowledge about "output_iterator" and Boost.Iterator can explain to me why an iterator using the "boost::random_access_traversal_tag" for the "CategoryOrTraversal" template parameter of "iterator_facade" will never get the category "output_iterator" (or "input_output_iterator_tag"). Regards, Thomas

4 6

DotNet FileSystemWatcher like library proposal.
by Fernando Pelliccioni 03 May '10

03 May '10

Hello all, I am working on a library like DotNet FileSystemWatcher ( http://msdn.microsoft.com/en-us/library/system.io.filesystemwatcher%28VS.80…) Basically the library monitors for file system changes and notifies throwing events. First, it will support the following platforms: - Windows NT 5.0 (Windows 2000) or higher using O/I Completion Port. - Linux 2.6.13 or higher using inotify. - FreeBSD 4.1 or higher using kqueue. - NetBSD 2.0 or higher using kqueue. - OpenBSD 3.6 higher using kqueue. (Not sure which version supports it) - MacOS/X 10.4 higher using kqueue. (Not sure which version supports it) Future supported platforms: - Linux from 2.4.0-test9 2.6.12 using dnotify. - Sun OpenSolaris using FEM API. Testing: I am testing the library on FreeBSD 7.2, Linux 2.6.31, Windows XP (Windows NT 5.1). I need help to test on older versions of these operating systems. Also in NetBSD, OpenBSD and mainly on MacOSX because I do not have the necessary hardware. I would like to include this library in Boost, I think would be useful. What do you think? If so, I would like to have a mentor (like GSoC) and experienced in Boost development. Thanks and regards, Fernando Pelliccioni --- References: - O/I Completion Port: http://msdn.microsoft.com/en-us/library/aa365198%28VS.85%29.aspx http://en.wikipedia.org/wiki/Input/output_completion_port - inotify: http://en.wikipedia.org/wiki/Inotify - kqueue: http://people.freebsd.org/~jlemon/papers/kqueue.pdf http://en.wikipedia.org/wiki/Kqueue - dnotify: http://en.wikipedia.org/wiki/Dnotify

6 8

Re: [boost] [castor] Interest in Logic Paradigm for C++ ?
by Joris IJsselmuiden 02 May '10

02 May '10

My humble opinion to the matter: I think it is a great idea to try and make Castor part of Boost. I have been using Castor in my research for a while now, and I think that it is definitely Boost-material. A logic engine can be a powerful tool, and it is a shame that C++ doesn't have one readily available. I am confident that Castor is the best choice for adding logic support to Boost. As far as I know, Boost is the most popular code-base that is not part of the C++ standard library yet. So, making Castor part of Boost would be a great way of increasing Castor's visibility. It would be nice to keep Castor available as a stand-alone library, so that you don't need Boost if you only want to use Castor. But I am sure that this issue can be solved: Castor could be a Boost "companion" library, or one could have a stand-alone version and a Boost version side-by-side. Although this last solution doesn't seem that great to me. I hope I will find the time to do some testing for Castor 1.1. Keep in touch! Joris Ijsselmuiden _________________________________________________________________ Hotmail: Powerful Free email with security by Microsoft. https://signup.live.com/signup.aspx?id=60969

3 3

Parallel Boost Algorithm
by anil khadka 02 May '10

02 May '10

I am pretty new to both boost and parallel boost. I am using Brandes Centrality algorithm, but the performance really doesn't meet my expectation. If I used Java, which is only using 1 CPU core would complete it in around 30 hrs. The parallel version which use 8 CPU cores tooks 17 hours!! I don't know why there is just around 13 hours gain if i use 8 cores against 1, unless there are lots and lots of communication between each cores. I am using just 1 machine (not a cluster), right now. Graph size is Node 80K, edges 120K I am reading edges from files. I used distributed compressed_sparse_row to represent graph. Right now, it seems like all the cpu cores are reading files on its own, I am assuming each CPU core will takes its graph part automatically (distributed algorithm do it ?). Note: I downloaded the parallel version from: http://osl.iu.edu/research/pbgl/software/ Any help/suggestions would be really appreciated. Metanil.

2 1