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

stuck with template programming
by DE 09 Dec '09

09 Dec '09

hi everyone i managed to write piece of code which seems to be valid c++ but compiles neither with msvc80 nor with icc11 the code is in the attachment if this question falls out of this maillist' scope please tell me where can i post it any ideas how to work around these problems? -- Pavel

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[integer]/cstdint.hpp How to use portable literals?
by vicente.botet 09 Dec '09

09 Dec '09

Hi, I need to use boost::intmax_t literals in a portable way. I remember some discussion related to this subject, but I've not found the thread. Could someone point me to these threads, or tell me how I can achieve this. I'm currently using the macro INTMAX_C, but it seems that this macro is not always defined. Thanks, _____________________ Vicente Juan Botet Escribá

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[property-map] Generalizing identity_property_map for arbitrary types
by Belcourt, Kenneth 09 Dec '09

09 Dec '09

Hi, I've found the property map library to be very useful and would like to propose a minor enhancement to permit the identity_property_map to work for arbitrary types. The reason for this is that some computationally intensive algorithms suffer noticeable performance degradation when I convert them to generic algorithms using property maps. Having a typed identity property map that returns, for example, the double passed into it significantly speeds up our algorithms, at least for those fields that are not mutable. I've attached a patch, and could supply a motivating example, if anyone is interested. -- Noel

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Blog and source code for "abstract_fsm"
by David Bergman 09 Dec '09

09 Dec '09

As I mentioned elsewhere, I created an abstract FSM interface for non-complex FSM's, translating to either Statechart or MSM in compile-time. There is a blog basically repeating what I posted earlier here at http://blog.davber.com/2009/12/08/abstract_fsm-finite-state-machines-in-c/ and the source code is found at http://github.com/davber/abstract_fsm. Hmm, I always have a hard time deciding which place should be the canonical one - with examples and such - the Github repository or the blog (post)! If somebody can tell what is Right and Wrong here, I would appreciate it ;-) /David

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[mpl] [type_traits] [enable_if] Overloading Problem with GCC 3.3.3
by Stewart, Robert 08 Dec '09

08 Dec '09

Can anyone figure out why GCC 3.3.3 doesn't like the following member function overloads? VC7/8/9 and GCC 4.1.2 have no problems with this code. #include <boost/mpl/and.hpp> #include <boost/mpl/not.hpp> #include <boost/type_traits/is_const.hpp> #include <boost/type_traits/is_convertible.hpp> #include <boost/utility/enable_if.hpp> struct Bar { }; template <class T> struct Baz { }; struct Foo { template <class T> typename boost::enable_if < boost::mpl::and_ < boost::is_convertible<T,Bar> , boost::mpl::not_<boost::is_const<T> > > >::type set(Baz<T> const & _value); template <class T> typename boost::enable_if < boost::mpl::and_ < boost::is_convertible<T,Bar> , boost::is_const<T> > >::type set(Baz<T> const &); }; GCC 3.3.3's error message is: error: `template<class T> typename boost::enable_if<boost::mpl::and_<boost::is_convertible<T, Bar>, boost::is_const<T>, mpl_::bool_<true>, mpl_::bool_<true>, mpl_::bool_<true> >, void>::type Foo::set(const Baz<T>&)' and `template<class T> typename boost::enable_if<boost::mpl::and_<boost::is_convertible<T, Bar>, boost::mpl::not_<boost::is_const<T> >, mpl_::bool_<true>, mpl_::bool_<true>, mpl_::bool_<true> >, void>::type Foo::set(const Baz<T>&)' cannot be overloaded _____ Rob Stewart robert.stewart(a)sig.com Software Engineer, Core Software using std::disclaimer; Susquehanna International Group, LLP http://www.sig.com IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.

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New libraries deadline approaching
by Vladimir Prus 08 Dec '09

08 Dec '09

Boosters, the deadline for merge of new libraries to 1.42 is Dec 14. So far, the only library that was added to trunk relative to 1.41 is uuid. Andy, does it seem like merge to release branch is possible by Dec 14? Do you need any assistance? It seems that you have succeeded in integrating the tests into the regression framework. However, one test -- test_generators, appear to fail on all platforms and test_uuid fails on a bunch as well. If the test failures are unclear, you might want to ask platform experts for help, while there is time. The next deadline will be Jan 4, when the release branch will be closed for major code changes. -- The Release Managers, Beman Dawes Daniel James Eric Niebler Rene Rivera Vladimir Prus

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[interval containers (itl)] Update on Review Version. Element iterators added.
by Joachim Faulhaber 08 Dec '09

08 Dec '09

Dear all, while hanging around in "The Queue" my library was getting pretty bored :-/ So I decided to implement some depreciated featured to arrange for some entertainment =) Well, jokes aside, for a long time I resisted to implement iteration on *elements* for interval containers. Element iterators would be an invitation to inefficient usage of interval containers just by normal habitual use of iterators. For instantiations with continuous domain types like interval_set<double>, interval_set<rational<int>>, interval_set<string>, etc. element iteration would not be possible at all. Yet the questions about such iteration and the related question of interval containers being a model of SortedAssociativeContainer reoccurred in many feed backs on presentations of my library. There even was a proposal for a DenseSet library by Vicente Botet in the wiki's Library Wish List: https://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction that follows the idea of interval containers but provides element iteration in order to fully implement SortedAssociativeContainer. So finally I decided to provide element iteration and put the responsibility to avoid inefficient deployment on the user. Moreover, while element iteration on interval containers can be substituted easily by simple loops, the element iteration over an interval_bitset that Zachary Turner asked for http://archives.free.net.ph/message/20091103.064651.263bf6bb.en.html is not so trivial, so it can not be substituted easily by a few lines of user code. That gave me some new motivation. So I have uploaded an update of my library's review version http://www.boostpro.com/vault/index.php?action=downloadfile&filename=itl_3_… to the vault that is extended by these features: * element iterators on all interval containers http://www.herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/boost_itl/fu… * itl::insert_iterator and itl::inserter that allows interval containers to be copied or transformed from std::containers using insert semantics http://www.herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/boost_itl/ex… * itl::add_iterator and itl::adder that allows interval containers to be copied or transformed from std::containers using addition semantics so that aggregate on overlap can be done. http://www.herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/boost_itl/ex… In the extended library itl_xt that is part of http://www.boostpro.com/vault/index.php?action=downloadfile&filename=itl_pl… * there is an implementation of a large interval_bitset, that combines interval compression and bit compression. Element iteration is now available for interval_bitset. https://svn.boost.org/svn/boost/sandbox/itl/boost/itl_xt/interval_bitset.hpp Element iteration now enables interval_containers to be used with std::algorithms like the corresponding containers of elements. The major requirement for usability of element iteration is that the interval container's domain_type is a discrete type that has a smallest steppable unit and exposes an increment and decrement operator for it's in- and decrementation. I have successfully tested copy (and variants), equal, lexicogrphic_compare, find, lower_bound, upper_bound, includes and set_<algorithms>. All tested algorithms that were applicable to a SortedAssociativeContainer of elements were also working with interval_containers using element_iterators. The test have been done using a law "AtomicEquivalence" https://svn.boost.org/svn/boost/sandbox/itl/boost/validate/laws/atomic_equi… on the law based test automaton (LaBatea) https://svn.boost.org/svn/boost/sandbox/itl/libs/validate/example/labat_sor… https://svn.boost.org/svn/boost/sandbox/itl/libs/validate/example/labat_sor… https://svn.boost.org/svn/boost/sandbox/itl/libs/validate/example/labat_sor… https://svn.boost.org/svn/boost/sandbox/itl/libs/validate/example/labat_sor… https://svn.boost.org/svn/boost/sandbox/itl/libs/validate/example/labat_sor… https://svn.boost.org/svn/boost/sandbox/itl/libs/validate/example/labat_sor… So I think this is a valuable addition to interval containers in the end and I hope it'll make std::algorithm aficionados among you happy ;-) Cheers Joachim ----------------------------------------------------------- Some repeated information on the library: Please note that the original ITL as presented in May 2008 has been split into 3 parts and only the *first* part was submitted for review (2009-09-18): itl : Core library, interval containers, SUBMITTED FOR REVIEW Additional parts are: itl_xt : Extensions like interval_bitset, histories and generalized crosstables validate: The law based test automaton (LaBatea). A validation tool using laws aka axioms. *itl* is a complete library containing all required ingredients particularly a separate test suite (NOT using LaBatea) and the quickbook documentation. The code is successfully compiled and tested with gcc-3.4.4, 4.1.0, 4.3.2 and msvc-8.0, 9.0, 10.0. I have uploaded the first update of the review version as itl_3_2_0.zip to the vault in section containers. http://www.boostpro.com/vault/index.php?action=downloadfile&filename=itl_3_… Another file itl_plus_3_2_0.zip contains all three parts (itl, itl_xt and validate). http://www.boostpro.com/vault/index.php?action=downloadfile&filename=itl_pl… Reviewers interested in the law based testing part may have to refer to this file to examine those tests. The law base testing examples compile and run with gcc-4.3.2, msvc-8.0, 9.0 and 10.0. LaBatea does not compile with gcc-4.1.0 or older. The quickbook generated documentation is included in the zip files and is also available online at http://herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/index.html Sources are also available form the sandbox: https://svn.boost.org/svn/boost/sandbox/itl/

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[type_traits] Need help with an - unfixable? - issue
by John Maddock 08 Dec '09

08 Dec '09

This issue just came in: https://svn.boost.org/trac/boost/ticket/3730 Reduced to the test case below, and I can't see a way to fix this at present, anyone any bright ideas? Thanks, John. #include <map> #include <iostream> #include <boost/type_traits.hpp> class base { public: base() : i(0) {} base(int i) : i(i) { m[i] = "text"; } virtual void method1() = 0; virtual ~base() {}; private: int i; std::map<int, std::string> m; }; class derived1 : virtual public base { public: }; class derived2 : virtual public base { public: }; class intermediate : public derived1, public derived2 { public: intermediate() {} intermediate(int i) : base(i) {} void method1(); }; void intermediate::method1() { } class final : public intermediate { public: final() {} final(int i) : base(i) {} }; // // This class demonstrates what we need to make work inside is_virtual_base_of. // MSVC compiles this just fine (likewise is_virtual_base_of), and only complains // when attempting to use method1. Other compilers (GCC, Intel on Linux) complain // as soon as X is declared, likewise when instantiating is_virtual_base_of. // struct X : final, virtual intermediate { X(); X(const X&); X& operator=(const X&); ~X()throw(); }; int main( int /* argc */, char* /* argv */[] ) { X x; x.method1(); boost::is_virtual_base_of<intermediate, final>::type t; return t.value != true; }

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Re: [boost] [msm] eUML guard/action location
by Christophe Henry 08 Dec '09

08 Dec '09

Hi Michael, hi Robert, hi Felipe, >CurrentState() + cool_event() >[VeeeeeryLoooooooooongGuard()] >/(LooooooooooooooooongAction()) = DestState() I just wanted to bring an example from SimpleTimer (see doc): Ringing() + tick() == Ringing() [ Source_<m_ringing_cpt>() - Event_<m_tick>() > Int_<0>() ] / (Source_<m_ringing_cpt>() -= Event_<m_tick>() ) would become: Ringing() + tick() [ Source_<m_ringing_cpt>() - Event_<m_tick>() > Int_<0>() ] / (Source_<m_ringing_cpt>() -= Event_<m_tick>() ) == Ringing() Here, it is becoming hard to write action and target state on the same line. And the action can be as big as one wishes. >Here's another suggestion, though it breaks from the logical UML ordering Michael posted previously: >DestState() = CurrentState() + cool_event()[guard()]/(action()) I like this one quite much! Not UML at all but pretty much C++-style. And it'd become easy to write guard and action on the next lines if needed. >CurrentState() + cool_event()[guard()]/(action()) -> DestState() It's very similar with Michael's syntax but I think the operator precedence can be hard to master and we'll need extra parentheses. I think there is no operator -> in proto but ->* . We are making progress :) Christophe

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Re: [boost] [msm] Review
by Christophe Henry 08 Dec '09

08 Dec '09

>FYI, this is an issue of -- apparently -- English not being Christophe's first language. >Darryl's construct, "This is unlike StateChart, where the idea of object instantiation as state is genuinely useful sometimes,..." >means "MSM's approach is unlike that of StateChart, because StateChart instantiates state objects, which is sometimes genuinely useful." > >I think there was more to the original sentence, which I haven't taken the trouble to recover from earlier posts, >which better developed what Darryl liked about MSM's own approach. >There was, however, no implication that MSM fails to meet expectations because it wasn't like StateChart in this behavior. > >For those for whom English is a second language, I apologize. >Few native English speakers learn the language well. We thus make our inherently complex language harder >still to understand by our mistakes of grammar, syntax, structure, and even word usage. >Add to that the many idiomatic constructs and expressions, not to mention colloquialisms, >we use that it's amazing that you manage to converse with us so well. Oh I see. Sorry Darryl for misunderstanding your post. Robert, thanks for your help! Christophe

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Re: [boost] [msm] eUML guard/action location
by Christophe Henry 08 Dec '09

08 Dec '09

Hi Michael, >Thank you for setting me straight on this. It should have dawned >on me that they were completion transitions as described in 15.3.14. >I have a love/hate feeling about them... I don't personally like >the concept of leaving a state via implicit trigger. It just makes >me feel uncomfortable. However, I also see the power they can >afford and use them for exactly your example... stepping along >algorithms. You taught me about simple states' internal transitions so let's count it a fair trade ;-) >Right now I'm pushing on the edges of what I'm learning from the docs >and a little bit of playing so I can determine how to convert basic >constructs I use a lot from the model to the implementation. Thanks >for putting up with me. You're welcome. I enjoy the discussion and await the harder questions which are surely coming. Christophe

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Re: [boost] [msm] Review
by Christophe Henry 08 Dec '09

08 Dec '09

Hi Darryl, >I agree with this. However, I have yet to come completely to terms with >how best to use msm. I am beginning to think, in trying to use it, that >it would be better to separate the state transition table definition as >much as possible from what, in an msm world, are more like semantic >actions. This is very different from the more oo modeling approach of >statechart. I'm not sure the statechart isn't better at expressing fsms >that "emerge" out of overall application/system design in an all >encompassing oo design uml world, and msm better at expressing more self >contained "islands" of fsm in an app As far as I can tell, state machines and OO modeling are completely orthogonal concepts. An OO implementation doesn't mean that FSMs are an OO concept. Can you precise your point with a concrete example? >I'm far from an expert with >spirit, but I think there are many concepts that could be borrowed from >it to make msm better able to be used to define a fsm that can be bound >to separate objects to implement behavior and exend its use beyond these >islands. Again, can you help us with more concrete examples? >Basically, it needs to be easier to take a 1 TU transition table >integrate it into to a bigger multi TU system What would it concretely bring? Compile-time improvements not really, so? >actions - the functor approach is good - though it needs a bit more >development to make it easier to bind to actions that are not explicitly >designed for use as msm state machine actions. What would it bring? You can simply ignore the functor arguments if you don't need them. A closer look at eUML will however show you that having your source/target states at hand in a transition handling can be pretty useful. >states - I don't really understand what an instance of a state is in msm >- it doesn't model anything meaningful to me. Where do you suggest putting the entry/exit actions and the flags? All in one big fat react function with lesser code reuse possibilites? And all the state data inside a fsm? Why giving up reuse of states? >This is unlike statechart, >where the idea of object instantiation as state is genuinely useful - >sometimes, and where it is the state that "reacts" to an event In UML, it is a state machine which reacts to an event, not a state. Statechart != UML (the same applies to MSM). Furthermore, "unlike Statechart" isn't a valid argument, is it? Making MSM look like Statechart is not the goal (besides, David would make us another round ;-) Just kidding, David) Could you please develop your point a little? >Should msm drop state objects altogether and simply have some sort of context / >current state object? Arguably it already has one in the form of the fsm >object - though that is a bigger concept than context. I disagree. I see no gain doing this. Just more confusing, tightly coupled, unreusable state machines. >Michael Caisse has already pointed out that there is something slightly odd about the >current state being represented as a scalar in a model that has objects >as states Did we read the same post? I didn't read all this in any of his posts. >I haven't spent much time thinking about this I also have this feeling, to be frank. If I understand, what you want is a MSM looking like Statechart. What for? I think a few concrete points would help us all. Of course, MSM could easily support a Statechart-like frontend, but nobody required this so far. I had the opposite feeling, that most people welcomed the lesser coupling offered by MSM. Or am I getting it wrong? Christophe

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[serialization] #3677: Please, pay attention to a serious regression
by Alexander Churanov 08 Dec '09

08 Dec '09

Folks, I've just re-opened the issue #3677, since I did not receive any specific feedback on how to resolve it. In the ticket it's claimed that the issue is fixed. However, for the question about how to obtain the patch it was answered that there is a belief the patch is checked in somewhere into the trunk. I completely understand that Boost is free and does not provide any warranty for quality and reliability of the libraries. However, I hope that there is a strong interest in Boost community for that. To my knowledge, the issue is cross-platform and may broke more applications than stated in the ticket. It is a pure regression: boost 1.39 is known to work. The issue is a showstopper, at least for FreeBSD: I may not update the boost to 1.41, because this action breaks working applications. The desired is any definite decision on the issue. Preferably, a fix or a workaround. Alexander Churanov, maintainer of devel/boost-*

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Re: [boost] [serialization] polymorphic archives runtime failure(was:polymorphic archives ... generates linker errors)
by Bogdan 08 Dec '09

08 Dec '09

I just want to confirm I have the same issue with boost 1.41.0 built with MSVC 9.0 (Visual Studio 2008). I have created two tests similar to the one Christoph describes ( both with and without DLLs) and I hit exactly the same assert in basic_serializer_map::find(). It looks like while deserializing B via A*, basic_iarchive_impl::load_pointer() is trying to recover a serializer from: boost::serialization::singleton< boost::archive::detail::archive_serializer_map<boost::archive::naked_xml_iar chive> > (or boost::serialization::singleton< boost::archive::detail::archive_serializer_map<boost::archive::naked_text_ia rchive> >, depending on the input archive actually used) but that map is empty. I checked boost::serialization::singleton< boost::archive::detail::archive_serializer_map<boost::archive::polymorphic_i archive> > in the first line of my program and it contains correctly two serializers (one for A and one for B, respectively), proving that the macro BOOST_CLASS_EXPORT_IMPLEMENT(.) has registered those classes. I am not sure why the serializers for A and B do not register with the specific polymorphic archives but only with the base archive. I was under the impression that the polymorphic archives are meant to make that process transparent to the user (especially future archives that are created later). I appreciate any feedback about this issue and please let me know if you need more details. Thank you, Bogdan PS I am using extended type_info_no_rtti. Deserializing via isomorphic pointers (B*->ser->dser->B*) is working.

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[regex][patch] regex build not honoring ICU_LINK build property
by Martin Schafföner 08 Dec '09

08 Dec '09

I have been trying to build boost.regex with Unicode support against a custom ICU4C build. The ICU4C build used the "--with-library-suffix=rm" configuration option to distinguish the library as being custom built. I tried building boost.regex with the bjam option like '-sICU_LINK="\"/LIBPATH:c:\icu4c\dist\libs\windows-i686 icuinrm.lib icuucrm.lib\""' but it failed to apply the linker flags. I then tried to understand what's going on and it seemed that the ICU_LINK property never makes it into the actual linker calls. With the attached patch against 1.41.0 the ICU_LINK build property works as expected. Regards, Dr. Martin Schafföner Core Technologies Recommind, Inc. Office: +49 2226 15 966 13 Email: martin.schaffoener(a)recommind.com This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is strictly forbidden. Diese E-Mail enthält vertrauliche und/oder rechtlich geschützte Informationen. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtümlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser Mail ist nicht gestattet.

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Re: [boost] [Regex] Why doesn't this pattern match?
by Vitalij Gotovskij 08 Dec '09

08 Dec '09

>> Yes, Robert, You are right. I am trying to change \\n (wchar_t '\' and >> wchar_t 'n') with a real new line symbols and it doesn't work. Allthought, >> then I am trying to find only wchar_t 'n' (or any other letter) everything >> is working good. The problem is that I have XML configuration file >> (Unicode), where all new lines are L"\\n" (!!! not '\n' !!!). I can't >> change that file format. Of course I can program that replace without >> boost::regex, but I am afraid that I'll loose my sleep afterwards... >> >>>> You're replacing each occurrence of \\n with \\n, so the >>>> string at the end should be exactly the same! :-) >> >>> The replacement is "\n" not "\\n" so the '\' followed by 'n' in str >>> should be replaced with a newline, right? > No. Remember the compiler gets first bite at the escape characters, so if > you put a string "\\n" in your program, that gets passed to Boost.Regex as > the two character string: "\n", which matches a single newline character. > If you want to match a \ followed by a \n then you need a regex of "\\\n". >HTH, John. You wanted to say: "\\\\n" ? :) Anyway, thanks a lot. This works! Didn't knew regex engine is working in that way... If he understands "\\\\n" as C++ "\\n" and "\\n" as C++ understands "\n", then how regex engine understands "\n" ...? Don't answer this letter. The problem is solved.

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[Regex] Why doesn't this pattern match?
by Vitalij Gotovskij 08 Dec '09

08 Dec '09

Hello, can, please, somebody explain, why this code doesn't work? std::wstring str = L"Line \\n line \\n line \\n"; std::wstring result = L""; const boost::u32regex e = boost::make_u32regex(L"\\n"); std::wstring newText = L"\n"; result = boost::u32regex_replace(str, e, newText); After launching result == str... :((( I also tryed with const boost::u32regex e = boost::make_u32regex("\\n"); but result was the same... I am using Regex from bost 1.37.0 compilled with ICU 4.2.1 Visual Studio 2008.

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[MSM] Comparison with ad-hoc FSM implementation
by Phil Endecott 08 Dec '09

08 Dec '09

Dear All, When we reviewed Andrey Semashev's proposed FSM library last year I presented a couple of examples of simple state machines encoded "ad hoc", i.e. primarily as switch statements that set the next state based on the current state and inputs, and asked "why is this library better?". I'm going to ask the same question of MSM. Consider the example presented in the documentation: struct cd_player_fsm { enum state_t { Stopped, Open, Empty, Playing, Paused }; enum event_t { play, open_close, stop cd_detected, pause, end_pause }; state_t state; void process_event(event_t event) { if (state==Stopped && event==play) { start_playback(); state=Playing; } else if (state==Stopped && event==open_close) { open_drawer(); state=Open; } else if (state==Stopped && event==stop) { state=Stopped; } else if (state==Open && event==open_close) { close_drawer(); state=Empty; } else if (state==Empty && event==open_close) { open_drawer(); state=Open; } else if (state==Empty && event==cd_detected && good_disk_format()) { store_cd_info(); state=Stopped; } etc. etc. } }; Of course one difference is that MSM has O(1) dispatch. We can get that too if we use a switch statement, maybe something like: switch ((state<<8) | event) { case (Stopped<<8)|play: start_playback(); state=Playing; break; case (Stopped<<8)|open_close: open_drawer(); state=Open; break; etc. etc. The greatest advantage of this ad-hoc style is that it is readable by anyone who has even the most basic understanding of C++ without the need to learn a new library, and its exact behaviour is immediately evident. It is also likely to compile and run quickly. I have no doubt that MSM has many benefits compared to this. Perhaps it would be useful to spell them out? Regards, Phil.

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Re: [boost] [msm] eUML guard/action location
by Christophe Henry 08 Dec '09

08 Dec '09

Hi Michael, >Ok... I looked up MSM's anonymous transitions again and >now I don't like it (o; It's probably because we don't talk about the same concept. And it's not an MSM concept. Sorry, I can't claim ownership for it ;-) Anonymous transitions are also called completion events in the standard (and both names are used in the excellent "Real-Time UML, 3rd Edition"). They are defined as a transition without explicit trigger and are generated after the entry actions. You can have a look at the tutorials to see how it is used. >Christophe ... as far as I can tell by looking at the docs, >the MSM use of anonymous transitions transforms the source >state to *almost* be a UML choice pseudo state I disagree with this. The state itself is not concerned, it is only a state machine thing. If you reuse the same state in another context, it will not behave like a choice point. But in this special state machine context, yes, it behaves the same, which is why I didn't implement choice points yet. Now you see what I meant ;-) I was at first not convinced by this feature until I saw a project in a big automotive company making extensive use of it. At every processor time slice, they'd go through the whole fsm used in this context as an algorithm. They could this way easily estimate the time slice they needed. What you are talking about is a trigger, which has to be fired, whatever it is. I didn't find it in the standard, but I could have missed that too. And no, MSM doesn't support it for the moment. The reason is that it's not on my radar as I'm pretty unconvinced of its need. I have yet to see a good convincing use case for it. Now, I don't say it won't be done, but it's not high on my list, unless someone makes a convincing case for it. Its implementation might be not trivial though. Christophe

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Re: [boost] [msm] Review
by Christophe Henry 08 Dec '09

08 Dec '09

Hi, >eUML makes up *~75%* of Msm's code and ~30% of Msm's documentation; metrically, >it's obviously an extremely significant part of Msm, and is probably what >warranted a major version increment between Msm versions 1.2 and 2.0. Correct. Although it is not the only reason, there is also a big redesign with division in front- and back-ends and riddance of the CRTP. Adam Merz wrote: >I could be way off here, but my impression from the Msm documentation >is that the standard frontend exists mostly for backwards compatibility >with 1.x code and to support older compilers, and that > eUML is the recommended frontend for new FSMs on supported compilers David Bergman wrote: >That was not my impression. My impression was that the (old) standard interface >was the canonical one, and eUML an "option" for developers. MSM has no favorite interface, but a choice of interfaces which it tries to support equally well. But it's true that eUML is my personal favorite way and the source of a great amount of fun. I personally thought (or say hoped) that it'd become the new way of writing state machines, but I came into this review without an idea of how it would be welcome. From what I saw for reactions until now, I'm pretty confident eUML will meet this goal at some point. >I would welcome eUML into Boost any day, from what I have seen (especially after playing with it this morning.) Great! >Do we really need a new underlying library for eUML, though? I am not sure of that. You don't get a new library for eUML but eUML for a new library. It's clearly not the same. >And even if we do (for now), and cherish the much faster execution speeds of MSM >(in my non-complex but pretty big state machine examples), I don't get what is the problem. You get a backend with impressive performance which was built with the goal to allow expressive, declarative and concise front-ends with great UML support and lots of work done under the hood which you can't even imagine. Without it, there would be no interface and no eUML. Why not have it? I thought that Boost was standing for state-of-the-art C++ coding and was happy to get any great library coming, no matter which library is already part of it. Don't we all agree on that? >I would argue for an attempt at having eUML as an optional facade for both MSM and Statechart. For this you'd need some important amount of change in Statechart, for which I cannot do anything. eUML being a representation of the underlying MSM philosophy, I doubt that you will have it. Let me get it straight. The biggest value of MSM is not the front-end, not even eUML, no matter how cool it is. It is the back-end. Actually it's the philosophy behind the back-end. Christophe

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[ratio] metafunction ratio_subtract
by vicente.botet 07 Dec '09

07 Dec '09

Hi Beman, Hi Howard, With current implementation of the metafunction ratio_subtract I get the type from the test ratio_test.cpp User1::Distance d( User1::mile(110) ); User1::Time t( boost::chrono::hours(2) ); typeof (d/t) is User1::quantity<boost::ratio<1,-1>, boost::ratio<1,1> > So the following assignation do not works User1::Speed s = d / t; as User1::Speed is defined as typedef quantity<boost::ratio<1>, boost::ratio<0> > Time; // second typedef quantity<boost::ratio<0>, boost::ratio<1> > Distance; // meter typedef quantity<boost::ratio<-1>, boost::ratio<1> > Speed; // meter/second The code is a little bit triky, and I have not taken the time to understand why the resulting type is User1::quantity<boost::ratio<1,-1>, boost::ratio<1,1> > and not <boost::ratio<-1,1>, boost::ratio<1,1> > User1::quantity I have replaced the type by typedef ratio<R1::num * R2::den - R2::num * R1::den,R1::den * R2::den> aux_type; typedef ratio<aux_type::num ,aux_type::den > type; // get normalized type to follow the recommendation "The nested typedef type shall be a synonym for ratio<T1, T2> where T1 has the value R1::num *R2::den - R2::num * R1::den and T2 has the value R1::den * R2::den." and every thing is OK (See below the replaced code) I'm doing something wrong? Best, _____________________ Vicente Juan Botet Escribá template <class R1, class R2> struct ratio_subtract { private: #if 1 typedef ratio<R1::num * R2::den - R2::num * R1::den,R1::den * R2::den> aux_type; #else static const boost::intmax_t gcd_n1_n2 = detail::static_gcd<R1::num, R2::num>::value; static const boost::intmax_t gcd_d1_d2 = detail::static_gcd<R1::den, R2::den>::value;#endif public: //The nested typedef type shall be a synonym for ratio<T1, T2> where T1 has the value // R1::num *R2::den - R2::num * R1::den and T2 has the value R1::den * R2::den. #if 1 typedef ratio<aux_type::num ,aux_type::den > type; #else typedef typename ratio_multiply < ratio<gcd_n1_n2, R1::den / gcd_d1_d2>, ratio < detail::ll_sub < detail::ll_mul<R1::num / gcd_n1_n2, R2::den / gcd_d1_d2>::value, detail::ll_mul<R2::num / gcd_n1_n2, R1::den / gcd_d1_d2>::value >::value, R2::den > >::type type; #endif };

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[ratio] Assignation between equivalent ratios
by vicente.botet 07 Dec '09

07 Dec '09

Hi, I was wondering if we need to be able to make assignations between equivalent ratios. e.g. ratio<1,3> r1; ratio<3,9> r2; r1 = r2; // (1) Reading N3000 even if they are equivalents (synonym ) as its num and den are the same, there is no defined assignation. So (1) should not compile with the current recomendation. IMO, this should compile, and so we need to add a specific assignement operator. Other example ratio<1,3> r1; ratio<2,3> r2; r1 = r2-r1; // the type of this expression could be ratio<3,9> so the compilation fails. Otherwise the recomendation should clarify the meaning of synonym on the ratio arithmetic operators [ratio.arithmetic] 2 "The nested typedef type shall be a synonym for ratio<T1, T2> where T1 has the value R1::num * R2::den + R2::num * R1::den and T2 has the value R1::den * R2::den." Maybe we should talk of normalized ratio and not of synonym. BTW, where is synonym defined? In addition I think that we need also to add that the declaration of no normalized ratios, as ratio<3,9>, must fail at compile time as it is not normalized and we can not assigne nothing to them. I'm missing something? Any thougths? Best regards _____________________ Vicente Juan Botet Escribá

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Re: [boost] [msm] Review
by Christophe Henry 07 Dec '09

07 Dec '09

Hi David, >The problem is this: if, *hypothetically*, eUML were the only substantial difference between this proposal >and what is already in Boost, I would argue for an implementation of that syntax on top of Statechart to be a more viable solution. Agreed. >As you spell out here - and I can confirm - that is not the only difference Happy that we finally agree ;-) >Perhaps, I would like to take on that challenge and see how far I can get. >I think it would be great to have a common transition-definition format for these two libraries, and being able to switch in compile-time. >Let me try to look at it a bit, and see what I can do. It would involve a lot of wrappers, unfortunately :-( As I wrote in another post, I find the idea hard but interesting and I can only encourage you to give it a try. >I enjoy being critical of things I like, which is why I always criticize my wife. I wouldn't try to push this too much with mine ;-) >So, take that as a good sign for my formal review (which has already been pushed one day due to my "common interface" sickness :-) ) I'll be happy to read it. I think that, while this common interface thing went a bit long, you brought interesting points to the review and even went the extra mile to not criticize without bringing at least a beginning of a solution, which is not a very common thing. Christophe

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Meta State Machine library review starts Monday
by David Abrahams 07 Dec '09

07 Dec '09

Dear all, With apologies for making this announcement so close to the review start date... The review of the Boost.Msm library starts this Monday, November 23rd and ends the December 6th. Msm was written by Christophe Henry, inspired in part by the example in the book "C++ Template Metaprogramming" (http://boostpro.com/mplbook) About the library: Msm (Meta State Machine) is a library allowing the user to easily define high-performance, straightforward and readable UML2 finite state machines, while respecting the principles of efficiency and declarativeness of the original example. To that end, Msm offers several Domain-Specific Embedded Languages that strive to closely emulate a standard UML diagram. Msm supports a broad range of UML features: - state entry/exit - transition actions/guards - composite states - history - orthogonal regions - terminate states - deferred events - explicit entry/fork - entry/exit pseudostates - anonymous transitions - transition conflicts And several non-standard features to make the developer's life easier (interrupt states, query about the current state(s)). Msm (in its current version, 2.0) can be found: * in the sandbox (http://svn.boost.org/svn/boost/sandbox/msm/) * or in the vault: (http://www.boostpro.com/vault/index.php?directory=Msm) Everybody on this list is invited to participate in this formal review. I hope to see your review of Msm, including your vote on acceptance, and I welcome your participation in the ensuing discussions on the Boost developers' mailing list. Please always include in your review a vote as to whether the library should be accepted into Boost. Additionally please consider giving feedback on the following general topics: - 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? Regards, -- Dave Abrahams Meet me at BoostCon: http://www.boostcon.com Review Manager BoostPro Computing http://www.boostpro.com

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Re: [boost] Meta State Machine library review starts Monday
by Christophe Henry 07 Dec '09

07 Dec '09

>I'm wanting to start discussing some more complicated >use cases of this library. Ideally I will just post >the UML HFSM diagram with my email so it is clear. Why not in the Vault in MSM's directory?

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