November 2012 - Boost-users - lists.preview.boost.org

Re: [Boost-users] [Who's using boost?] Algocoders : books on c++11, Boost and Beyond
by Erika James 27 Nov '12

27 Nov '12

On 28 November 2012 02:53, Algocoders . <algocoders(a)gmail.com> wrote: > > It is the pioneering efforts at boost towards "Using and Extending C++11, > Boost and Beyond" which has motivated us to devote ourself in developing > bullet-size capsules in the form of tiny booklets with industrial-set > framework to lift the thin veil with initial focus on practical usage of > C++11 vis-a-vis mathematical foundation behind it. > Wow, that's quite a mouthful! I read the excerpt of your first book on the website, and particularly enjoyed the final paragraph: *One thing was very much clear that, the naive looking interface* *was mere a rosy picture, hiding many unpleasant surprises in its bosom,* *which we thought of unfathoming it to its fullest. * I've never heard a C++ interface described as a bosom! I think you should rename the book to "Fifty shades of Boost"! ~Erika

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[Review] Review results for Coroutines
by Hartmut Kaiser 24 Nov '12

24 Nov '12

All, The review for the Coroutines library written by Oliver Kowalke started September 3rd 2012, and ended on September 12th 2012. I counted 7 votes, none of which were NO. All authors votes YES, some made additional requests. Overall, the verdict of the community was clear: Oliver Kowalke's Coroutines library is ACCEPTED The discussion was lively and it touched on several points. Design ------ The Coroutines library offers enormous potential for programming regimes such as communications software and embedded systems design. Oliver selected a sensible granularity for his design. This granularity allows for fine-tuning the implementations of cooperative scheduling mechanisms while avoiding the prohibitively heavy weight of preemptive scheduling that is found in POSIX and often in implementations of the C++11 thread support library. In particular, the separation of Coroutines from Context allows for porting to other systems with minimal effort and maximum reliability and code re-use. Some suggestion related to the API have been made during the review, most of which (if not all) have already been addressed. Oliver has a full list of things and works on integrating the suggestions. Here is a short list: - allow to specify the allocator to use for memory allocations inside the library - remove 'self' pointer and replace with TLS - add symmetric coroutines API - better support for generator functionality Naming ------ Some of the people participating in the discussions suggested not to use the abbreviated 'namespace coro', but to use the full 'namespace coroutines' instead. This again is not a precondition for acceptance. Documentation ------------- The consensus of almost everybody referring to the documentation was that it is terse but readable and sufficient. People suggested to integrate the docs of the old Coroutines library (written as an GSoC project by Giovanni P. Deretta) into the documentation of the reviewed library. I would like to thank all who participated in the discussions. Regards Hartmut --------------- http://www.cct.lsu.edu/~hkaiser http://stellar.cct.lsu.edu http://boost-spirit.com

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Re: [Boost-users] [Range & c++0x Lambdas] Can this be done?
by John M. Dlugosz 24 Nov '12

24 Nov '12

------------------------------ Message: 3 Date: Thu, 22 Nov 2012 11:31:05 -0800 From: "Jeffrey Lee Hellrung, Jr." <jeffrey.hellrung(a)gmail.com> To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] [Range & c++0x Lambdas] Can this be done? Message-ID: <CANvXPuQmePirYFadBKRyVoQur1N8DH2c-QhwqHgZMV2MNfG_gQ(a)mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" > Maybe this is what you did, so I might not be suggesting something new, > but... Perhaps boost::result_of could have an extra conditional logic > branch added to it: I don't recall the details, but I've learned that result_of has compatibility issues with old/new ways in general. So, if the "old way" is published at all, use it (for backward compatibility, in case it is different from what decltype would detect). This allows lamdas and other code that assumes decltype is being used, while preseving the behavior of code that explicitly publishes the type. > - If F::result_type exists, return F::result_type; > - Else: << same as before >> Meanwhile, for different reasons, I made a macro that abstracts the >> different syntax between C++11 lambdas and Apple Block Closures. The latter >> generates a suitable lambda class complete with result_of member. That >> makes me think that you could have a macro that wraps a compiler-generated >> lambda expression in another class that inherits the operator() etc. and >> adds in the result_of typedef to simply use decltype. >> > Wouldn't that require defining a class at expression scope? Is that > possible? > > - Jeff > Here's my docs on the matter: Given a macro M, at its simplest M can expand to either [=] or ^ depending on the platform, and then be followed by the optional lambda-declarator and compound-statement. However, Apple's Blocks do not have proper value semantics. You must call a function on it before leaving the scope where it was defined, if it is to be used outside of that scope. And then it needs to be explicitly destroyed when it is no longer needed. In order to use it transparently in C++, it needs to be wrapped in an object with a destructor, (and that wrapper can take care of the initial function call too). But we don't want to have to inject anything _after_ the compount-statement, or the macro syntax would be difficult, requiring either fully-bracketing macros or double parens around the whole thing. Meanwhile, the wrapper object needs to be templatized to provide the correct typed operator() forwarding function. My (JMD's) solution is to use an operator, which can take a second argument as trailing text without being wrapped in parens. That is, M would expand to dummy| ^ so that after the trailing text (not seen by the macro) you get: dummy| ^(ARGLIST){BLOCK} that is, the completed Apple Block Literal Expression becomes the second argument of the operator|, and my special object is the first argument. The operator| can be a template, and break open the Block type in the same manner as can be done for normal function pointer declarations. For wrapping a C++ lambda, reason is different (add the decltype) but you still return an instance of a class with the right stuff in it. The return value is a templated type, wrapper0<Ret>, wrapper1<Ret,A1>, or wrapper2<Ret,A1,A2> (etc) (an emulation of "..." for some fixed number of arguments) So, the _type_ is not unique, but reused for each time the same operator() is needed. The instance holds the underlying (wrapped) instance as a member. For Apple Blocks, that is just their variation on a function pointer, so the type goes with the signature. To wrap C++11 lamdas, the underlying instance has a unique type. So use _that_ as the template argument, and generate another unique type that you can inherit from. Using an operator| to add the wrapper, you can explicitly pull it in when needed along with any other filters that are being applied.

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"cross-running" boost tests
by Gottlob Frege 23 Nov '12

23 Nov '12

I've managed to cross-compile boost for BlackBerry10 devices. (Side-note: there is very little docs on cross compiling) Now, how would I go about "cross-running" the boost tests? In particular, can I hook into the unit-test and/or run rules of Boost.Build? Given a command line, I can load and run it on device and then retrieve the results, I just need to know where to hook in. Tony

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Re: [Boost-users] "cross-running" boost tests
by Lemay.Steve 23 Nov '12

23 Nov '12

Can you share how you succeeded a cross compiling the tests, I didn't have luck. - Sent via iPhone -----Original Message----- From: Gottlob Frege [gottlobfrege(a)gmail.com<mailto:gottlobfrege@gmail.com>] Sent: Thursday, November 22, 2012 12:28 PM Pacific Standard Time To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] "cross-running" boost tests That is along the right track. But I don't want to have to do that for every boost test file. This isn't for my own tests, I want to run the boost tests. I sort of need a global launcher that I can hook into. On Thu, Nov 22, 2012 at 1:40 PM, Paulo Márcio Figueiredo Alves <pauloalves1986(a)gmail.com<mailto:pauloalves1986@gmail.com>> wrote: You could use testing.launcher, like this: b2 testing.launcher=my_custom_launcher It'll call my_custom_launcher to run your tests. On Thu, Nov 22, 2012 at 4:28 PM, Gottlob Frege <gottlobfrege(a)gmail.com<mailto:gottlobfrege@gmail.com>> wrote: On Thu, Nov 22, 2012 at 1:11 PM, Vicente J. Botet Escriba <vicente.botet(a)wanadoo.fr<mailto:vicente.botet@wanadoo.fr>> wrote: Le 22/11/12 16:51, Gottlob Frege a écrit : I've managed to cross-compile boost for BlackBerry10 devices. (Side-note: there is very little docs on cross compiling) Now, how would I go about "cross-running" the boost tests? In particular, can I hook into the unit-test and/or run rules of Boost.Build? I guess you should see how Boost.Build could support this. Best, Vicente Right. That's kind of what I'm asking. Does Boost.Build support this already? Is there a way to hook into 'run'? I don't find Boost.Build (or docs) easy to use/understand, so my poking around at it didn't find anything, but I could have easily missed it. Tony _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org<mailto:Boost-users@lists.boost.org> http://lists.boost.org/mailman/listinfo.cgi/boost-users _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org<mailto:Boost-users@lists.boost.org> http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Re: [Boost-users] list serialization with boost
by Brian Wood 22 Nov '12

22 Nov '12

Krzysztof Czainski: >2012/11/22 Olivier Austina <olivier.austina(a)gmail.com> > >> Hello, >> I am a newbie of boost and I want to use it. I would like to serialize a >> list. The list is defined with the following data type: >> >> typedef struct person { >> char *name; >> char *first_name; >> struct person *next; >> } person; >> >> person *list_person; >> > > I'd suggest reorganizing your struct into struct person { std::string > first_name; } and useing std::list<person> list. Then serializing and > other operations would probably be trivial. Shalom Another option would be an intrusive list -- http://www.boost.org/doc/libs/1_52_0/doc/html/intrusive.html . The serialization library in Boost doesn't provide support for intrusive containers, but the C++ Middleware Writer -- http://webEbenezer.net has support for intrusive list and rbtree. If you use std::list, the C++ Middleware Writer has some advantages -- http://webEbenezer.net/comparison.html over the serialization library in Boost. (There are serialization and deserialization tests with std::list there.) -- Brian Ebenezer Enterprises -- so far G-d has helped us. http://webEbenezer.net (651) 251-9384

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[mpl] How to use not_ with has_trivial_destructor metafunction
by Christian Henning 22 Nov '12

22 Nov '12

Hi there, I have troubles compiling the following code with Visual C++ 2010 and boost 1.52. #include <boost/mpl/not.hpp> #include <boost/type_traits/has_trivial_destructor.hpp> #include <boost/utility/enable_if.hpp> template <typename T> void foo( typename boost::enable_if< boost::mpl::not_< boost::has_trivial_destructor< T > > >::type* /*ptr*/ = 0 ) { int i = 9; } int main(int argc, char* argv[]) { foo< int >(); return 0; } The error I'm getting is: error C2770: invalid explicit template argument(s) for 'void foo(boost::enable_if<boost::mpl::not_<boost::has_trivial_destructor<T>>>::type *)' Can someone see what the problem might be? Thanks, Christian

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[Range & c++0x Lambdas] Can this be done?
by Robert Jones 22 Nov '12

22 Nov '12

Can the last line, labelled NOT Ok, be made to work? I think the lambda does not publish its result as a bind does, so I suspect it's hopeless. Any thoughts? Thx, Rob. #include <boost/range/adaptor/transformed.hpp> #include <boost/range/algorithm_ext/push_back.hpp> #include <boost/bind.hpp> #include <vector> #include <algorithm> struct S { int i; }; void f( std::vector<int> & out, std::vector<S> & in ) { using boost::adaptors::transformed; // Ok std::transform( in.begin( ), in.end( ), std::back_inserter( out ), bind( & S::i, _1 ) ); // Ok boost::range::push_back( out, in | transformed( bind( & S::i, _1 ) ) ); // Ok std::transform( in.begin( ), in.end( ), std::back_inserter( out ), []( S & s ) { return s.i; } ); // NOT Ok boost::range::push_back( out, in | transformed( []( S & s ) { return s.i; } ) ); }

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list serialization with boost
by Olivier Austina 22 Nov '12

22 Nov '12

Hello, I am a newbie of boost and I want to use it. I would like to serialize a list. The list is defined with the following data type: typedef struct person { char *name; char *first_name; struct person *next; } person; person *list_person; I have the list built from this structure and I want to serialize it on the hard disk. -- Regards Austina

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[Intrusive] unordered_set and thread safety
by Alexandre Hamez 22 Nov '12

22 Nov '12

Hello, I'm currently using intrusive:: unordered_set in a single threaded application. But now, I need to switch to a multi threaded application. As such, the unordered_set must be protected. I don't want to block the whole table with a single mutex. Thus, it would be fine to have a lock per bucket. Furthermore, intrusive:: unordered_set provides a bucket_traits mechanism to enable some customization. So, my question: is it possible to use bucket_traits to have a lock per bucket? Thank you! -- Alexandre Hamez

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