November 2009 - Boost-users

[Spirit] [bind] Compiler warning dependent on number of rules?
by Norbert Wenzel 05 Nov '09

05 Nov '09

Hello, I'm currently parsing some data using Spirit together with boost::bind to set the callbacks for Spirit. In release build I get a compiler (gcc 4.4.1) warning from bind: warning: dereferencing pointer ‘val’ does break strict-aliasing rules I was able to find the lines causing this problem by commenting them out, rebuilding and the error got away. The strange thing is, that when I copy some other parsing rules, that previously compiled without any warning, I get the same warning again. When trying to create a simple example to post here, it seemed that the actual parsing code (that is the only code that uses boost::bind) was exchangeable. It was the number of options in the parsing rule that caused the warning to appear (which I really do not understand). The parsing rule looks like this: parse(someString.c_str(), ( *( str_p('+') >> str_p('(') >> real_p[boost::bind(&Object::func_param, boost::ref(m_curObmect), _1)] >> str_p(')') | str_p('+')[boost::bind(&Object::func, boost::ref(m_curObject), _1)] /*| str_p('+') >> str_p('(') >> real_p[boost::bind(&Object::func_param, boost::ref(m_curObmect), _1)] >> str_p(')') | str_p('+')[boost::bind(&Object::func, boost::ref(m_curObject), _1)] [... to be repeated ...] */ ) ) , space_p).full; The goal is to find either "+" or "+(double)", which works as expected. causesThe signatures of the Object functions are Object::func_param(double param); and Object::func(char); The rule can be copied 7 times, leading to 14 options, without any warning. If I add one 8th copy of these lines, or if I just add a 15th option (independent of the actual line I copy) I get the warning again. My system is an Ubuntu Karmic 64bit machine, using gcc 4.4.1, boost 1.39 headers and simply including "boost/spirit.hpp", which means I get the deprecation warning for that file at the moment. I'd be thankful for any suggestions, since for now, I do not even know where to look further. I do not have any idea what might cause this warning. thanks, Norbert

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multi_index and shared_ptrs
by Daniel Burrows 05 Nov '09

05 Nov '09

I'm having trouble getting multi_index's key extractors to play nicely with shared_ptr objects. I'm trying to eliminate my custom hash and equality objects in this code: class screenshot_cache_entry : /* ... */ { /* ... */ public: const screenshot_key &get_key() const; /* ... */ }; class hash_cache_entry { public: size_t operator()(const boost::shared_ptr<screenshot_c ntry> &entry) const { return boost::hash<screenshot_key>()(entry->get_key()); } }; class cache_entry_equal { public: bool operator()(const boost::shared_ptr<screenshot_cache_entry> &entry1, const boost::shared_ptr<screenshot_cache_entry> &entry2) const { return entry1->get_key() == entry2->get_key(); } }; typedef multi_index_container< boost::shared_ptr<screenshot_cache_entry>, indexed_by< hashed_unique<tag<by_screenshot_tag>, identity<boost::shared_ptr<screenshot_cache_entry> >, hash_cache_entry, cache_entry_equal>, sequenced<tag<ordered_tag> > > > cache_map; Note that all my custom hash and equality comparisons do is invoke get_key() and pass through to the corresponding operation on it. I've been back and forth over the documentation and past mailing list posts, and it seems like this "should" work: typedef multi_index_container< boost::shared_ptr<screenshot_cache_entry>, indexed_by< hashed_unique<tag<by_screenshot_tag>, const_mem_fun<screenshot_cache_entry, const screenshot_key &, &screenshot_cache_entry::get_key> >, sequenced<tag<ordered_tag> > > > cache_map; However, when I compile this, I get an error indicating that the index is attempting to apply hash() to the *shared pointer* rather than to the key object (at least it didn't just hash the pointer silently!) (...) screenshot_cache.cc:526: instantiated from here /usr/include/boost/multi_index/hashed_index.hpp:439: error: no match for call to ‘(const boost::hash<const aptitude::screenshot_key>) (const boost::shared_ptr<gui::<unnamed>::screenshot_cache_entry>&)’ With the ordered index, I get a similar problem (it tries to compare a screenshot_key to a shared_ptr). Can anyone shed some light on this problem? Thanks, Daniel

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boost::pool
by Hansjoerg 05 Nov '09

05 Nov '09

Hello, In my application I have a lot of small objects. For that I thought that it is the best to use an object pool..I have read the docu of object_pool...but I don't understand really how I have to use it.. Can one give me some hints? Another thing that I don't understand..Need I to know already during compiletime the max. number of objects? Regards Hansi

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multi_index with base class member
by david joeyoung 05 Nov '09

05 Nov '09

please give me some advices. I get a compile error,when to index on base class member. the codes are listed below: struct Foo { int a; }; struct Bar : public Foo { int b; }; struct idx0 {}; typedef multi_index_container< Bar, indexed_by< ordered_unique< tag < idx0 > ,member < Bar,int,&Bar::a> > > > test_type; Error 1 error C2440: 'specialization' : cannot convert from 'int Foo::* ' to 'int Bar::* ' and the codes are compiled in boost 1.40, vs 2008 sp1

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[scoped_ptr] How to cast from bast type to decived type
by Mario Klebsch 05 Nov '09

05 Nov '09

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello! I have a scoped_ptr<base_t>, which I reset() to new derived_t().: class base_t { }; class derived_t: public base_t { void Method(void) {} }; boost::scoped_ptr<base_t> Ptr; Ptr.reset(new derived_t()); Prior to using a scoped_ptr, I could write: ((derived_t*)Ptr)->Method(); I tried the following: boost::dynamic_pointer_cast< derived_t, base_t >(Ptr)>Method(); but it does not compile. :-( boost::dynamic_pointer_cast seems to only work for shared_ptr. Can anybody help me? 73, Mario P.S: I am using boost 1.38 - -- Mario Klebsch mkl(a)innodyne.de Innovative Dynamics GmbH http://www.innodyne.de Wiesenweg 9 Tel: +49 5304 91 19 410 38533 Vordorf / Rethen Fax: +49 5304 91 19 412 Geschäftsführer: Dipl. Phys. Gerhard Heidkamp Sitz: 38533 Vordorf - Rethen, Wiesenweg 9 Handelsregister beim Amtsgericht Hildesheim HRB 100553, USt-Id Nr. DE 215 876 442 SICHERHEITSHINWEIS: =================== Diese Email ist elektronisch signiert. InnoDyne versendet grundsätzlich seit dem 11.9.2006 verbindliche Dokumente nur als signierte PDF - Dateien oder elektronisch nachprüfbar signierte Emails. Juristisch und technisch verbindliche Dokumente dürfen das Haus InnoDyne nicht als andere Datei- formate verlassen. Sollten Sie ein signiertes, technisch oder kauf- männisch/juristisch verbindliches Dokument in einem anderen Dateiformat als PDF oder signierte Email von InnoDyne erhalten, so ist dies sehr wahrscheinlich ein Versehen des Versenders, eine Software - Fehlfunktion oder schlimmer noch, eine Fälschung. Wir bitten in einem solchen Fall um sofortige Information und Übermittlung solcher Dokumente an gl(a)innodyne.de -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (Darwin) iEYEARECAAYFAkrywpMACgkQDwNq2neCwq7SbwCfewiXKOvyymLeWOMjkLqmmPbi 5aYAnR5FTZiuHfbQHSg21QEXOZN8j3Zc =Kz/D -----END PGP SIGNATURE-----

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[BGL] How to set a complex edge property using add_edge
by Cosimo Calabrese 05 Nov '09

05 Nov '09

Hi to all, I'm trying to use the add_edge( u, v, *p*, g ) overload of this function, but I've founded only example where the edge property of the graph is a single property. // ... typedef adjacency_list<vecS, vecS, directedS, no_property, property<edge_weight_t, int> > Graph; Graph g( 10 ); // add an edge with weight = 1 property<edge_weight_t, int> edge_property( 1 ); add_edge( 0, 1, edge property, g); // ... What about if I've multiple edge property? // ... typedef property < edge_ID_t, long, property < edge_weight_t, long, property < edge_other_prop_t, bool > > > edge_prop; typedef adjacency_list<vecS, vecS, directedS, no_property, edge_prop> Graph; // ... How can I set an edge_prop variable with all the edge properties? Thanks in advance, Cosimo Calabrese.

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[boost] [Review Results] Boost.Polygon library accepted into boost
by Fernando Cacciola 05 Nov '09

05 Nov '09

Dear Boosters, [first of all allow me to apology for not doing this before. My small consulting bussines suddenly grew out of proportion and now is way over my head, keeping me working/managing 16 hours a day] I am pleased to announce that the Boost.Polygon library from Lucanus Simonson has been accepted into boost provided some of the most critical concerns, detailed below, are addressed first. First of all I would like to thank Lucanus and Intel Corporation for making this work available to all C++ developers around the world. I would also like to thank all the reviewers that participated (in no particular order nor degree of participation) Thomas Klimpel Frank Mori Hess Barend Gehrels Andreas Fabri Jeffrey Hellrung Tim Keitt Markus Werle Paul A. Bristow Robert Stewart Mathias Gaunard Michael Fawcett Steven Watanabe Joachim Faulhaber John Bytheway Sebastian Redl Mika Heiskanen John Phillips Kai Benndorf Hartmut Kaiser Arash Partow Maurizio Vitale Brandon Kohn David Abrahams Gordon Woodhull Daniel James John Maddock Tom Brinkman Bo Persson Mateusz Loskot Christian Henning Jean-Sebastien Stoezel The library had 6 yes votes and 4 no votes. Those who voted no made the following major complains and remarks (they are numbered as I will refer to them back later): Barend Gehrels: (1) According to his benchmarks, intersection algorithms are unnecesarily slow as if something where fundamentally wrong in the design and/or implementation. AFAICT the implication has not been proved or disproved so far, hence I consider it a red herring and cannot take it as a reason for rejecting the library, but it is important to look at it in detail. (2) As a major complain, the library is unusable in those domains where floating point support is a requirement (like GIS). (3) The library should contain some basic polygon geometry algorithms such as convex hull and centriod Phil Endecott: (4) There is no concept checking in the code so it is difficult to adapt. (5) There where too many warnings and build errors (but Luke fixed these) (6a) The documentation needs a better overview of operations supported by the concetps. (6b) It also needs the details on the algorithms complexities. (6c) It also misses the numerical requirements for the coordinate type. (6d) And tutorials. (7) Some operators are ambiguous and it would be better to keep just one of each "flavor". (8) The polygon_data template class is parameterized by a coordiante type rather than a point type. This makes it useless for integration with existing geometric data types Michael Fawcett: (5), (6a), (6d) (9) T9he API should provide versions using output iterators in addition to output container references. (10) Theoreticall the library would be usable with a user defined coordinate type (metting certain requirements now undocumented), for example a fixed point data type, but some details in the internal design and implementation prevents this. (11) As a major complain, the library is unusable in those domains where floating point support is a requirement (like GIS). Hartmut Kaiser: (11), (1) Fernando Cacciola: (12) The name of the library should change to better indicate that is restricted to Integral coordinates and two-dimensions. (13) The documentation must contain a "credits" section acknowledging all the people that participated in the review. For the library to be effectively accepted, points (5),(6a-d),(10), (12) and (13) should properly addressed ((5) is already done AFAICT) It would be quite significant if point (1) where looked into. Once again I thank Lucanus, Intel Corporation and all the reviwers. Best regards -- Fernando Cacciola SciSoft Consulting, Founder http://www.scisoft-consulting.com _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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[1.41.0] Beta 1 available
by Beman Dawes 05 Nov '09

05 Nov '09

Boost release 1.40.1 beta 1 is available from SourceForge: http://sourceforge.net/projects/boost/files/ This release contains one new libraries and numerous bug fixes for existing libraries. For details, see http://beta.boost.org/users/news/version_1_41_0for details. To install the beta on your system, see http://beta.boost.org/doc/libs/1_40_0/more/getting_started/index.html Please report any problems with the beta on the developers or users mailing list. Unless unexpected problems arise, the plan is to ship the final 1.40.0 release in a week to ten days. Thanks, --The Boost release team

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Warning while compiling asio UNDER_CE
by Carmelo Campione 05 Nov '09

05 Nov '09

I'm trying to compile my project with Asio support for Windows CE platform. I think, I don't need to define _WIN32_WINNT or _WIN32_WINDOWS but when compiling Asio headerI get this warning: "Please define _WIN32_WINNT or _WIN32_WINDOWS appropriately. For example:..." I find this warning coded in "socket_types.hpp" file. I'm using Boost library 1.40.0. How can remove this warning message? Can I ignore it? Thanks. Carmelo

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[1.41.0] CMake beta of the beta
by troy d. straszheim 04 Nov '09

04 Nov '09

The CMakeable 1.41.0 Boost has gone beta. Docs: http://sodium.resophonic.com/boost-cmake/1.41.0.beta1.cmake1/doc Tarballs and zipfiles: http://sodium.resophonic.com/boost-cmake/1.41.0.beta1.cmake1 If you've been waiting to try the cmake build, this is the time. Followups on the boost-cmake list, please, contact info at the top of the docs. -t

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