April 2011 - Boost - lists.boost.org

[Fusion] Tentative of trasnform_if failed :(
by falcou 20 Apr '11

20 Apr '11

The following code http://ideone.com/xYk4X doesn't compile and i cant get the why of it. The goal is to have a fusion transform_if that takes a compile-time predicates For each element int he sequence, if the predicates its true, we apply some transform on it, if not we return the element unchanged. What am I missing ?

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Interest in doing project "concept Traits library"
by Rachit Kulshreshtha 20 Apr '11

20 Apr '11

I know that i am running late as i had my university exams but i have been following the projects entitled under Google Summer of Code 2011. I am a student of BITS-Pilani University, India doing my B.E. in Electronics and Instrumentation. I was going through the project "concept traits library" , trying to understand it. I was able to gather much information about what it is and how it works, with some details of the functions under operator traits, mpl_ext and even Concept traits. But since their is no well defined problem statement given on the website, i was wanting to know what functions \ templates already exist as parts of the library and what are we expected to create. Please reply soon... Thnx in advance -- its a bird, its a plane, its a rocket no its Rachit

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Re: [boost] [MSM] Interrupt anonymous transitions or blocking process_events?
by Christophe Henry 20 Apr '11

20 Apr '11

Hi Mathias, <snip> >By calling p.process_event(play()); the the player will start playing >Song1 and then change to the next song by itself. But now in single >threaded mode it blocks until it reaches "Song3". So it is not possible >to process any other events during this time. In other words, it cannot >process another process_event call. The "Playing" state has a "stop" >event but calling this will not help as it will not be processed until >the MSM has reached "Song3". The problem is that a state machine is based on run-to-completion. This means in your case that a transition must be "short". An event comes, a transition is executed, the state machine is in a new stable state and can process a new event. Until this happens, events are queued (in the case of MSM). >I start the same p.process_event(play()); in thread 1. And in thread 2 I >call p.process_event(stop()); The problem with this is that the stop() >event does not get processed until it reaches Song3 because of the >blocking call in p.process_event(play());. Actually I'd think because of the mutex. In any case, your design will be hard to get right I'm afraid. >Perhaps I am going about this the wrong here and please tell me if it >can be done in some other much better way! I want to be able to have >automatic transitions that I can interrupt. You have to use run-to-completion. Base your design on short-terms events fed to the state machine, which triggers work and reacts to changes in forms of other events. In your case, one possibility would be to have the state machine delegate (post) some work upon state entry or transition action to a thread, then posting a new task upon state exit, etc. Make your state machine be serviced by only one thread, triggering work and reacting to events. Trust me on that one, having a state machine serviced by 2 threads is a good receipt for headaches ;-) If you know boost::asio, it's a bit like the async_xxx methods, trigger some work and get ready for the next action (which would be a callback, to continue with this asio example). HTH, Christophe

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[preprocessor] seq/size.hpp BOOST_PP_SEQ_SIZE MSVC empty list warning
by damien benoist 19 Apr '11

19 Apr '11

Hello, It seems that BOOST_PP_SEQ_SIZE generates a warning with empty sequences under MSVC (vs 2010/boost 1.46.1). The same call works with gcc. The tests are available below. I've also put a patch but: - I'm really not sure of it (I have never been as far with preproceesor as in boost/preprocesor/) - I only tested it with BOOST_PP_CONFIG_MSVC (it should also be tested with BOOST_PP_CONFIG_EDG) And anyway this warning will likely appear with all macros manipulating sequences. Should this warning just be ignored or disabled with MSVC? More general question: I'm discovering boost. I'm really impressed by the macros in boost/preprocessor. It makes a lot of things possible. But it provides features the preprocessor was not meant for. For that, it uses a lot of tricks. How portable is it? How many architectures is it known to work/not work with? Can we be confident that it should work with any preprocessor? Thanks for your help. $ cat lstsz2.h #include "boost/preprocessor/seq/size.hpp" #define lst0 #define lst1 (a) #define lst2 (a)(b) #define lst3 (a)(b)(c) BOOST_PP_SEQ_SIZE(lst0) BOOST_PP_SEQ_SIZE(lst1) BOOST_PP_SEQ_SIZE(lst2) BOOST_PP_SEQ_SIZE(lst3) $ cpp -I ~/wh/softs/boost/1.46.1 < lstsz2.h ... 0 1 2 3 $ cl -I `cygpath -d "$HOME/wh/softs/boost/1.46.1"` /E lstsz2.h ... 0 1 2 3 lstsz2.h(8) : warning C4003: not enough actual parameters for macro 'BOOST_PP_SEQ_SIZE_I' $ diff -u 1.46.1/boost/preprocessor/seq/size.hpp.old 1.46.1/boost/preprocessor/seq/size.hpp --- 1.46.1/boost/preprocessor/seq/size.hpp.old 2005-06-21 09:55:15.000000000 +0200 +++ 1.46.1/boost/preprocessor/seq/size.hpp 2011-04-19 14:42:02.218750000 +0200 @@ -13,6 +13,7 @@ # define BOOST_PREPROCESSOR_SEQ_SIZE_HPP # # include <boost/preprocessor/cat.hpp> +# include <boost/preprocessor/empty.hpp> # include <boost/preprocessor/config/config.hpp> # include <boost/preprocessor/tuple/eat.hpp> # @@ -21,7 +22,7 @@ # define BOOST_PP_SEQ_SIZE_I(par) BOOST_PP_SEQ_SIZE_II ## par # define BOOST_PP_SEQ_SIZE_II(seq) BOOST_PP_CAT(BOOST_PP_SEQ_SIZE_, BOOST_PP_SEQ_SIZE_0 ## seq) # elif BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_EDG() || BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MSVC() -# define BOOST_PP_SEQ_SIZE(seq) BOOST_PP_SEQ_SIZE_I(seq) +# define BOOST_PP_SEQ_SIZE(seq) BOOST_PP_SEQ_SIZE_I(seq BOOST_PP_EMPTY()) # define BOOST_PP_SEQ_SIZE_I(seq) BOOST_PP_CAT(BOOST_PP_SEQ_SIZE_, BOOST_PP_SEQ_SIZE_0 seq) # elif defined(__IBMC__) || defined(__IBMCPP__) # define BOOST_PP_SEQ_SIZE(seq) BOOST_PP_CAT(BOOST_PP_SEQ_SIZE_, BOOST_PP_CAT(BOOST_PP_SEQ_SIZE_0, seq))

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[TypeTraits] Are any of the new C++2011 traits implementable using SFINAE expressions?
by John Maddock 19 Apr '11

19 Apr '11

I'm quite sure the answer to this is no.... but are there any new language features in C++2011 that would allow the implementation of any of the following traits within the language? Thanks in advance, John. template <class T> struct is_trivial template <class T> struct is_trivially_copyable template <class T> struct is_standard_layout template <class T> struct is_literal_type template <class T, class... Args> struct is_constructible; template <class T> struct is_default_constructible; template <class T> struct is_copy_constructible; template <class T> struct is_move_constructible; template <class T, class U> struct is_assignable; template <class T> struct is_copy_assignable; template <class T> struct is_move_assignable; template <class T> struct is_destructible; template <class T, class... Args> struct is_trivially_constructible; template <class T> struct is_trivially_default_constructible; template <class T> struct is_trivially_copy_constructible; template <class T> struct is_trivially_move_constructible; template <class T, class U> struct is_trivially_assignable; template <class T> struct is_trivially_copy_assignable; template <class T> struct is_trivially_move_assignable; template <class T> struct is_trivially_destructible; template <class T, class... Args> struct is_nothrow_constructible; template <class T> struct is_nothrow_default_constructible; template <class T> struct is_nothrow_copy_constructible; template <class T> struct is_nothrow_move_constructible; template <class T, class U> struct is_nothrow_assignable; template <class T> struct is_nothrow_copy_assignable; template <class T> struct is_nothrow_move_assignable; template <class T> struct is_nothrow_destructible; template <class T> struct underlying_type;

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Re: [boost] [Filesystem] error including filesystem v3 with icpc -std=c++0x
by Galen Andrew 19 Apr '11

19 Apr '11

> > Hello, > > > > Including boost/filesystem.hpp is giving me errors using Intel > > compiler in Linux with -std=c++0x that look like > > > > > boost/filesystem/v3/operations.hpp(303): error: name followed by "::" > > must be a class or namespace name > > {detail::copy_file(from, to, > > copy_option::fail_if_exists);} > > ^ > > It compiles fine under g++ -std=c++0x. > > What happens with the Intel compiler if you don't specify -std=c++0x? Without -std=c++0x those errors are gone, but a similar error pops up in another boost library I'm using boost/random/variate_generator.hpp(209): error: name followed by "::" must be a class or namespace name typedef typename random::detail::engine_helper<have_int, want_int>::BOOST_NESTED_TEMPLATE impl<decorated_engine, typename Distribution::input_type>::type internal_engine_type; ^ > The regression tests are passing for Intel on Linux, but it doesn't > look like any of them specify -std=c++0x > > What version of the Intel compiler are you using? Version 12.0.2.137 Build 20110112 > > What version of Boost are you using? 1.46.1 Thanks!

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[network] Release 0.9.0
by Dean Michael Berris 19 Apr '11

19 Apr '11

Good day everyone, apologies for the cross-post. I just wanted to point everyone interested in the development of the cpp-netlib project to the 0.9.0 release announcement over at C++ Soup: http://cplusplus-soup.com/2011/04/18/cpp-netlib-0-9-0-released/ -- more information about what happened in the library between the beta and the official release can be found there. As earlier mentioned, this version is the pre-1.0 snapshot that is being officially submitted to the Boost C++ Library as Boost.Network. I would like to ask the review wizards to please accept this announcement as a request to put Boost.Network/cpp-netlib into the review queue pending a review manager. I would greatly appreciate volunteers who would like to be the review manager(s) for the Boost.Network review. Have a good one and I definitely hope this helps. Cheers from down under! -- Dean Michael Berris http://about.me/deanberris

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[gsoc] Review needed --- BGL extension : community detection algorithm
by Xu Sun 19 Apr '11

19 Apr '11

Hi, Thanks for Robert's advise. I've posted my proposal on 04/05 but still didn't receive any reply including email or comment. I will be very appreciated if any one can give me any feedback about my proposal. The link is here: http://www.google-melange.com/gsoc/proposal/review/google/gsoc2011/sunbow/1 And the abstract: Implement new library based on Blondel's method and Newman's method providing community detection functionality into Boost libraries. Through this library, users can get their input direct/indirect weighted/unweighted graph segmented based on the criterion that the nodes within the same community have a more significant relationship than those between different communities. Sorry to bother others. Thanks, Xu Sun

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[OT] Boost Users/Developers Down Under?
by Dean Michael Berris 19 Apr '11

19 Apr '11

Hey Everyone! Apologies for the cross post and off-topic, but I just moved to Sydney, Australia and I was wondering whether there are any Boost users/developers that are based here who'd like to get together for a geek out session somewhere in the city? I tried to look at the Boost Users Map (http://goo.gl/O1I15) and I only saw one other Boost user in the area -- maybe there are others lurking around who'd be interested in a meet-up here? :) Cheers from down under! :D -- Dean Michael Berris http://about.me/deanberris

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FW: [locale] Off-list review
by steve.bush＠neosys.com 19 Apr '11

19 Apr '11

-----Original Message----- From: boost-bounces(a)lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Vicente BOTET Sent: 19 April 2011 10:33 >Hi, I have the impression that this review has already been sent at Date: Sat, 16 Apr 2011 15:40:53 +0400 . >BTW, who sent it? I did. I am sorry for wasting everybody's time. I joined the list immediately afterwards and have followed the very lively discussion intently since then. Artyom is quite resolute in the defence of his design decisions some of which brutally practical compromises - even if theoretically ugly. Things like broken standard libraries and "Broken" csv just aren't going to be fixed. This particular library has to live in the real world of existing libraries, not a vacuum, so the exquisite design purity which is so much a part of many boost libraries is less a consideration here. One of the strengths of the library seems to be that Artyom has used it in production for some years, although apparently mainly in posix/utf-8 environment and without CJK. I seriously doubt there will be any better offer for internationalisation library than this and it may trigger a better solution later on. If that is the case then this review better try to identify any unacceptable features in the library - especially those that cannot be replaced in future versions. If there are few or none then I think it should be admitted. Steve Bush

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