October 2010 - Boost - lists.boost.org

[Range] Composite Range
by Robert Jones 06 Oct '10

06 Oct '10

Is there any facility supported in Boost to provide a 'composite' range? I.e., a range that might be a vector, followed by a bit of list, followed by a pair of iterators? I guess the iterator classification of such a range would be the lowest common denominator of the classifications of all the component iterators, and I don't even want to think about how sort() would work, but it might be quite handy. - Rob.

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[Review] Formal Review: Boost.Ratio
by Anthony Williams 06 Oct '10

06 Oct '10

Hi everyone, The review of Vicente Botet' Ratio library starts October 2nd and lasts until October 11th, 2010, unless an extension occurs. What is it? ======== Portable implementation of the C++0x Standard Library's compile-time rational arithmetic working on C++03 and C++0x compilers. See the current C++0x working draft at http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3126.pdf Boost.Ratio provides: * A class template, ratio, for specifying compile time rational constants such as 1/3 of a nanosecond or the number of inches per meter. ratio represents a compile time ratio of compile time constants with support for compile time arithmetic with overflow and division by zero protection * It provides a textual representation of boost::ratio<N, D> in the form of a std::basic_string. Other types such as boost::duration can use these strings to aid in their I/O. This library is header-only and is designed to be generic and useful in a lot of areas of math and numerics C++ programming, in particular it is absolutely needed for the proposed Boost.Chrono and Boost.Stopwatches libraries which are currently in the review queue. Getting the library ============= The latest version of this library may be downloaded from vault: http://www.boostpro.com/vault/index.php?action=downloadfile&filename=ratio.… SVN: http://svn.boost.org/svn/boost/sandbox/chrono (directories boost/ratio and libs/ratio) and the docs may be viewed here html: http://svn.boost.org/svn/boost/sandbox/chrono/libs/ratio/doc/html/index.html pdf: http://svn.boost.org/svn/boost/sandbox/chrono/libs/ratio/doc/ratio.pdf You can get all these information also (which should avoid some long links) from http://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction#Boost.Ratio It is worth noting that the tests included in the zip file are relatively sparse. Vicente has an extensive suite of tests licensed under the LLVM license. He has posted a message on the Boost Developers mailing list regarding the license requirements for tests (See http://thread.gmane.org/gmane.comp.lib.boost.devel/208978) and is awaiting the outcome of that discussion before making the tests available. Writing a review ================ If you feel this is an interesting library, then please submit your review to the developer list (preferably), or to the review manager. Here are some questions you might want to answer in your review: - 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? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Anthony Review Manager for the proposed Boost.Ratio library -- Author of C++ Concurrency in Action http://www.stdthread.co.uk/book/ just::thread C++0x thread library http://www.stdthread.co.uk Just Software Solutions Ltd http://www.justsoftwaresolutions.co.uk 15 Carrallack Mews, St Just, Cornwall, TR19 7UL, UK. Company No. 5478976

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[fusion] for_each
by Christophe Henry 06 Oct '10

06 Oct '10

I think it's at least partly my mistake. It took me some time to manage a limited example not compiling: #include <boost/fusion/container/set.hpp> #include <boost/fusion/container/vector.hpp> #include <boost/fusion/include/at_key.hpp> #include <boost/fusion/include/for_each.hpp> #include <boost/fusion/include/as_vector.hpp> struct A { int adata; }; struct B { int bdata; }; struct C { int cdata; }; typedef boost::fusion::set<A, B, C> my_set_type; typedef boost::fusion::vector<A, B> my_vector_type; struct update { update(my_set_type& to_overwrite_):to_overwrite(to_overwrite_){} template<typename T> void operator()(T& elt) const { boost::fusion::at_key<T>(to_overwrite)=elt; } my_set_type& to_overwrite; }; int main() { my_set_type my_set; my_vector_type my_vec; boost::fusion::for_each(boost::fusion::as_vector(my_vec),update(my_set)); } Now it will compile if you replace boost::fusion::as_vector(my_vec) by my_vec or T& by T const&. Ok so it seems my problem description is wrong and I needed to know that as_vector returns a const vector, right? Thanks, Christophe

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Differences between Boost.Thread and std?
by David Abrahams 06 Oct '10

06 Oct '10

Hi All, Is there a document somewhere describing the differences between Boost.Thread and what's being proposed for C++0x? Thanks, -- Dave Abrahams BoostPro Computing http://www.boostpro.com

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Re: [boost] [fusion] for_each
by Christophe Henry 05 Oct '10

05 Oct '10

>> I have 2 fusion containers: a small vector (my_vec) and a bigger set >> (my_set). I want to overwrite the elements of the set with elements >> from the vector whenever they have the same type. Sounds simple: >> >> struct update >> { >> update(my_set_type& to_overwrite_):to_overwrite(to_overwrite_){} >> template<typename T> >> void operator()(T& elt) /*const?*/ >> { >> boost::fusion::at_key<T>(to_overwrite)=elt; >> } >> my_set_type& to_overwrite; >> }; >> >> boost::fusion::for_each(my_vec,update(my_set)); >> >> Except that this won't compile because the operator() is required to >> be const, which is sad, because it was very simple. > > And it won't compile *with* the const? I don't think the const'ness of > the member function affects the const'ness of the referent of to_overwrite. No, it won't compile ;-)

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[serialization] assert missing
by Andrew Sutton 05 Oct '10

05 Oct '10

The header 'boost/serialization/item_version_type.hpp' seems to be missing an include on boost/assert.hpp (or cassert) that was causing some compilation failures in the graph_parallel tests (under GCC-4.4.3 on GNU/Linux x86_64). The test case brings this in by including serialization/list.hpp. My first thought was to simply stick an appropriate #include in the item_version_type. Would there be any problems committing this change? Andrew

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[Review] Formal Review of Proposed Boost.Ratio Library Starts TODAY
by nimaca2001＠libero.it 05 Oct '10

05 Oct '10

> > - What is your evaluation of the design? > - What is your evaluation of the implementation? Take this as the review from an average C++ user that uses uses simple boost stuff like shared_ptr or bind but is scared of things like MPL or Spirit. > - What is your evaluation of the documentation? Well written, I would have omitted some appendixes (F and G). > > - Did you try to use the library? With what compiler? Did you have any problems? Tried the provided samples and some self written one on MSVC 9 without problems despite the fact I was using an old version of boost (1.41) as base. > > - How much effort did you put into your evaluation? A glance? A quick > - reading? In-depth study? About one hour to read the docs and compile a few tests > > And finally, every review should answer this question: > > - Do you think the library should be accepted as a Boost library? Yes

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[fusion] [intro] ADAPT_STRUCT extensions
by Stefan Strasser 04 Oct '10

04 Oct '10

Hi, in the discussion about the library I called "Intro" at the time it has been suggested to use BOOST_FUSION_ADAPT_STRUCT of Boost.Fusion for data member access. based on that I'd like to propose two extensions to ADAPT_STRUCT, which I think are useful beyond my use case: 1) ADAPT_STRUCT can adapt public data members only. with the modifications I uploaded here: http://svn.boost.org/svn/boost/sandbox/intro/boost/fusion/adapted/struct/ all data members can be adapted. for example: class A{ private: friend class fusion::access; int a; }; BOOST_FUSION_ADAPT_STRUCT(A,(int,a) ) 2) adaption of a class including its base class members. for example: struct A{ int a; }; struct B{ int b; }; struct C : A,B{ int c; } BOOST_FUSION_ADAPT_STRUCT(A,(int,a) ) BOOST_FUSION_ADAPT_STRUCT(B,(int,b) ) BOOST_FUSION_ADAPT_DERIVED( C, (A)(B), (int,c) ) an instance of C is now a fusion sequence of size 3. http://svn.boost.org/svn/boost/sandbox/intro/boost/fusion/adapted/struct/ad… private inheritance is supported as above, virtual inheritance is not. I'm not sure if virtual inheritance can be supported.

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Boost.SQL?
by Roland Bock 04 Oct '10

04 Oct '10

Hi, currently I am working on a set of header files which are supposed to make the life of C++ developers easier when in comes to interacting with databases (based on SQL). Goals are: * Stay close to SQL syntax * Do as much type checking as possible * prevent oversights and typical security holes, e.g. by forgetting to escape strings The basic idea is, that given a table definition, it should be possible to * offer a lot of checks at compile time for building a query * make it hard to misinterpret the results Until now, I have been concentrating on table definitions and select statements. Here's a very simplistic example, assuming a table definition "my_table" and a database connection "db": // ------------------------------------------------------------------------- using boost; typedef my_table<> t; typedef sql::select_record<t> record; std::string name("Peter"); ... std::vector<record> records = db.select<record>( sql::where(t::id() > 1000 && t::first_name() == name), sql::order_by(t::priority()(sql::desc)), sql::limit(17)); // the values can be accessed by their name // and are of the correct type, e.g. records.front().first_name_; // is a string records.front().middle_name_; // optional<string> because the table definition says that it can be NULL // In case of a select from more than one table, the values can also be accessed like this records.front().my_table_.first_name; // ------------------------------------------------------------------------- I wonder if there would be interest for such a library in boost.

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[config] additions for gcc 4.0.1 and IBM V11.1.0.0duetoMSM compile errors
by Christophe Henry 04 Oct '10

04 Oct '10

John Maddock wrote: > The updated test is passing as well, looks like this may be a case of adding > a BOOST_WORKAROUND for Apple's GCC and see if it fixes things. I added some #if for Apple's gcc and the IBM compiler. A look at the regression tests (http://www.boost.org/development/tests/trunk/developer/msm.html) shows: - all problems with Apple's gcc 4.0.1 are gone (waow cool! Better than expected) - IBM's compiler manages a few test cases more (for others, it just crashes or gives a run-time error status 139 which does not bring me much further) This is in my eyes a proof that for these compilers, BOOST_NO_NESTED_FRIENDSHIP and BOOST_NO_MEMBER_TEMPLATE_FRIENDS should be defined. If these features only work sometimes, then they should not be seen as supported. We now have 2 possibilities: - we change boost.config to reflect this situation and I update my code accordingly - we don't and I have to keep my #if. Solution 2 is not great for me because I'm duplicating boost.config and it litters my code with stuff less clear than BOOST_NO_NESTED_FRIENDSHIP and BOOST_NO_MEMBER_TEMPLATE_FRIENDS. In any case, it'd be good if we could decide on it this week on it so that this makes it to the 1.45. Thanks, Christophe

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