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meta state machine, process_event need to copy given event
by SBAM 13 Feb '15

13 Feb '15

Hello Christophe, I'm a boost msm first time user and I'm attempting to pass an event to my msm that cannot be copied. This event contains a /unique_ptr/ and my goal is to eventually steal it and store it under my msm. However, even with no deferred events, events are /copied/ to an internal queue, in /boost::msm::back::state_machine::do_pre_msg_queue_helper/. I just wanted to know if there was any chance /process_event/ could be overloaded and accept rvalue-ref or if by design, it's absolutely mandatory to copy those events. Many thanks for your great library -- View this message in context: http://boost.2283326.n4.nabble.com/meta-state-machine-process-event-need-to… Sent from the Boost - Users mailing list archive at Nabble.com.

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Performance optimization in Boost using std::vector<>
by saloo 12 Feb '15

12 Feb '15

Hello everybody, I have a question related to performance optimization using Boost. I found this link http://www.boost.org/doc/libs/1_41_0/doc/html/mpi/performance.html <http://www.boost.org/doc/libs/1_41_0/doc/html/mpi/performance.html> and trying to figure out which curve (on the graph in the link) represents the communication of std::vector<int> and std::vector<double>? Is communication using std::vector<int> and std::vector<double> optimized (is_mpi_datatype) or not? So I use "boost_mpi" and "boost_serialization" libraries. I include the header "#include <boost/serialization/vector.hpp>" in my code. Then I send directly std::vector<int> and std::vector<double> using "world.send(...) " and world.recv(...)" calls. I fill the vector with some values (for example I fill ten values) and I get the same ten values on other side of processor boundary. This thing works but I want to improve communication performance. I found out in this link http://www.boost.org/doc/libs/1_57_0/doc/html/mpi/tutorial.html under section "User-defined data types" that "Fixed data types can be optimized for transmission using the is_mpi_datatype type trait. ". Also I studied the information on http://www.boost.org/doc/libs/1_57_0/doc/html/mpi/tutorial.html#mpi.perform…. Also this link http://www.boost.org/doc/libs/1_46_1/libs/serialization/doc/wrappers.html#a… shows that std::vector<> are optimized for serialization. I am now confused that sending std::vector<> like this is good for performance optimization or not? What other better methods are available? Is something like this http://www.boost.org/doc/libs/1_57_0/doc/html/mpi/tutorial.html#mpi.skeleto… a good option? Best Regards, Salman Arshad -- View this message in context: http://boost.2283326.n4.nabble.com/Performance-optimization-in-Boost-using-… Sent from the Boost - Users mailing list archive at Nabble.com.

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Min cut between two vertices, undirected graph
by Mads Jensen 12 Feb '15

12 Feb '15

Hi, The Stoer Wagner implementation only takes as input a complete graph, and then it computes the min cut with the parity map indicating which cut set the vertex belongs to. I need something for computing the minimum cut between two arbitrary vertices given as input for an undirected graph. Edmonds Karps works just for a directed graph. Any help with this will be highly appreciated. -- Med Venlig Hilsen / Kind regards, Mads Jensen Max Jerry Horovitz: "Unfortunately, in America, babies are not found in cola cans. I asked my mother when I was four and she said they came from eggs laid by rabbis. If you aren't Jewish, they're laid by Catholic nuns. If you're an atheist, they're laid by dirty, lonely prostitutes." -- Mary and Max (2009)

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Which URL should I use in ExternalProject_Add
by Yi-Hong Lyu 11 Feb '15

11 Feb '15

Hello all, I used CMake's ExternalProject_Add to download and build boost in my project. The URL I used is ' http://sourceforge.net/projects/boost/files/boost/1.55.0/boost_1_55_0.zip/d…' and it works. However I got an error several days ago like: CMake Error: Problem with archive_read_open_file(): Unrecognized archive format It seems that what I download by CMake becomes 'HTML document, ASCII text' rather than 'Zip archive data, at least v2.0 to extract'. Could you tell me which URL should I use in ExternalProject_Add? Thanks, Yi-Hong

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boost iOS8 failure
by David Medine 11 Feb '15

11 Feb '15

First of all, I know that calls for help are not appropriate to the list, so let me disclaim by saying that I am not asking for help, simply reporting an issue. I am attempting to compile a C++ library (that uses boost) for iOS8 distribution. The library compiles fine on OSX (and Linux and Windows) but will not compile for iOS8. I get dozens of compiler complaints regarding boost headers that all involve some sort of 'Semantic Issue'. For example, in boost's hash.hpp, I get a 'No matching function for call to 'has_value' error on these lines (439-442): | BOOST_HASH_SPECIALIZE_REF(std::string) #if !defined(BOOST_NO_STD_WSTRING) BOOST_HASH_SPECIALIZE_REF(std::wstring) #endif | In this case I was able to skirt the issue by adding code to define the function hash_value for std::string and std::wstring: inline std::size_t hash_value( std::string const &v) { return hash_range(v.begin(), v.end()); } inline std::size_t hash_value( std::wstring const &v) { return hash_range(v.begin(), v.end()); } I am probably going to go through all such failures of clang to interpret the boost code correctly for iOS compilation and modify the source just so I can get this going. This is a major pain because there are dozens of these, many of which are far less straightforward to remedy. Besides I don't necessarily want a custom version of boost that ships with my library. I have the build settings in my iOS project (I'm using XCode) exactly the same as they are in the OSX project. I don't understand why the compiler behaves differently for these two targets. Finally, there are two stackoverflow questions that I posted related to this problem. http://stackoverflow.com/questions/28422862/clang-different-when-compiling-… http://stackoverflow.com/questions/28308466/ios8-boost-hash-hpp-system-cloc… THX!

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[gsoc15] Google Summer of Code 2015 ideas needed before 20th Feb
by Niall Douglas 10 Feb '15

10 Feb '15

Dear Boost community, The Google Summer of Code 2015 organisation application period has begun. We need project ideas for our ideas page at https://svn.boost.org/trac/boost/wiki/SoC2015, plus anyone willing to mentor. Last year we got eight slots, the previous year seven slots. Let's try to get back to ten slots for 2015! Niall & Boris --- Boost C++ Libraries Google Summer of Code 2015 admin https://svn.boost.org/trac/boost/wiki/SoC2015

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Problems/crash update a Spirit grammar from Boost 1.47 to 1.57
by Christoph Duelli 10 Feb '15

10 Feb '15

Updating Boost from 1.47 to 1.57 the code no longer compiles. It boils down to Both these includes are included (at various places) and these 2 lines compiled in 1.47 but no longer under 1.57. #include <boost/spirit/home/qi.hpp> #include <boost/spirit/home/phoenix.hpp> Changing #include <boost/spirit/home/phoenix.hpp> to #include <boost/phoenix.hpp> the code does compile, but causes crashes while parsing. (I was not able yet to narrow that down.) Is the correct way of porting a 1.47 boost spirit grammar to 1.57, to replace the old phoenix V2 header to #include <boost/phoenix.hpp> ? (Are there known issues? Or is there a "porting howto"?) Or is it still possible to use Spirit with Phoenix V2? Best regards -- Christoph Duelli --------------------------------------------------------------------------------- MELOS-Medizinische Labor-Organisations-Systeme GmbH Franz-Beer-Straße 6 86459 Gessertshausen Tel.: +49 8238/9611-0 Fax: +49 8238/9611-99 mailto: info(a)melosgmbh.de URL: www.melosgmbh.de Amtsgericht Augsburg, HRB 13226 USt-IdNr. DE 130 958 139 Geschäftsführer: Herbert Mayer, Andreas Manntz, Helmut Welsch -------------------------------------------- This e-mail (including any attachments) is confidential and may be privileged. If you have received it by mistake, please notify the sender by e-mail and delete it from your system. Any unauthorised use or dissemination of this e-mail or its contents in whole or in part is strictly prohibited. Please note that e-mails are susceptible to change. MELOS GmbH shall not be liable for the improper or incomplete transmission of the information contained in this communication nor for any delay in its receipt. MELOS GmbH does not guarantee that the integrity of this communication has been maintained nor that this communication is free of viruses, interceptions or interference.

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[gsoc15] Attn: We need 2015 mentors and project ideas for Boost!
by Niall Douglas 10 Feb '15

10 Feb '15

Dear Boost community, We are now within one month of the beginning of Google Summer of Code 2015! Last year's GSoC furthered the continuing success of the Boost GSoC programme with the first ever Boost funded extension to a GSoC project (that being Boost.Hana by Louis Dionne mentored by Joel Falcou, congrats to both of them on passing an exceptionally tough selection process), and over $50,000 of Google funding brought to Boost in 2014. We also sent three representatives to last year's mentor summit, including one student whose entire expenses the Boost Steering Committee very generously covered. As part of filling in our application for 2015, we must supply to Google a list of potential GSoC mentors and potential GSoC projects for summer 2015. There are a number of changes to how we design project ideas for students this year intended to improve the GSoC experience for both students and mentors, so please examine the ideas page which outlines those changes at https://svn.boost.org/trac/boost/wiki/SoC2015 and if you have any questions or concerns about those changes, please ask now rather than just before the GSoC deadline. If you think yourself able to mentor a student doing some work on Boost this summer, *please* consider adding a description of the proposed work item and your name to the list. Last year we acquired eight slots from Google and had to disappoint two mentors and students, we hope with the improved selection process we can get back to the ten annual slots we once had. If you want to know more about mentoring a Google Summer of Code funded student work before you nominate yourself, please feel free to ask on the main Boost developers mailing list boost(a)lists.boost.org. Thank you in advance for your time. Niall Douglas (Boost Google Summer of Code admin) Boris Schäling (Boost Google Summer of Code admin) --- Boost C++ Libraries Google Summer of Code 2014 admin https://svn.boost.org/trac/boost/wiki/SoC2014

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[iostreams] How to utilize zlib setDictionary method
by Ringel, Rick 10 Feb '15

10 Feb '15

I have a use-case that requires highly efficient bandwidth utilization over a narrow WAN connection, where communication is message-oriented. I have successfully used boost to gzip, zlib, and bzip2 my messages, and ran some numbers (bzip2 is best so far). However, in researching and profiling zlib's native API, I found I could improve efficiently by an additional 15% over bzip2 by using zlib's SetDictionary methods for deflate and inflate. How would I go about extending boost:iostream's zlib_compressor and zlib_decompressor classes to utilized a predefined/static dictionary? Or, is it best just to use zlib's API directly, and bypass boost for this specialized zlib compression case? -Rick

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Re: [Boost-users] Boost-users Digest, Vol 4049, Issue 1
by David Frank 09 Feb '15

09 Feb '15

Thanks Howard ! On Monday, February 9, 2015 12:00 PM, "boost-users-request(a)lists.boost.org" <boost-users-request(a)lists.boost.org> wrote: Send Boost-users mailing list submissions to boost-users(a)lists.boost.org To subscribe or unsubscribe via the World Wide Web, visit http://lists.boost.org/mailman/listinfo.cgi/boost-users or, via email, send a message with subject or body 'help' to boost-users-request(a)lists.boost.org You can reach the person managing the list at boost-users-owner(a)lists.boost.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Boost-users digest..." Today's Topics: 1. Re: Signals2 benchmark (Klaim - Jo?l Lamotte) 2. Re: Signals2 benchmark (Michael Powell) 3. write starvation of upgradable lock (David Frank) 4. Re: write starvation of upgradable lock (Howard Hinnant) 5. Re: Signals2 benchmark (Nevin Liber) 6. Re: [Serialization] XML: float format is scientific instead of human-readable since Boost 1.57 (Frank St?hr) 7. Re: Signals2 benchmark (Dominique Devienne) ---------------------------------------------------------------------- Message: 1 Date: Sun, 8 Feb 2015 18:49:06 +0100 From: Klaim - Jo?l Lamotte <mjklaim(a)gmail.com> To: Boost users list <boost-users(a)lists.boost.org> Subject: Re: [Boost-users] Signals2 benchmark Message-ID: <CAOU91ON-+ywWjniue3n56sYSy2ZALtYykDN9ehLp4Qcm6BYoxg(a)mail.gmail.com> Content-Type: text/plain; charset="utf-8" On Sun, Feb 8, 2015 at 4:42 PM, Michael Powell <mwpowellhtx(a)gmail.com> wrote: > On Sun, Feb 8, 2015 at 8:02 AM, Klaim - Jo?l Lamotte <mjklaim(a)gmail.com> > wrote: > > > > > > An executor takes arbitrary tasks as input and only > > guarantee that these tasks will be executed, under some constraints > > defined by the specific executor type. > > A signal dispatch it's call and parametters to a set of observers. > > Using the Boost.Signals2 for example, it is easy AFAIK to type-define > a signal, and re-use that type anywhere that signal is required. So a > listener could receive a signal, and subsequently do whatever it > wanted to with that message; dispatch it again, process it, > whatever... > > Yes but the executor would specify how the observers are notified, not how the observer's work is executed (which depends on the observer implementation indeed). There is an important nuance here.

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boost variant + boost serialization unused type
by Merrill Cornish 09 Feb '15

09 Feb '15

Using boost::variant with boost::serialization gives me a warning about unused type in the boost::serialization namespace: D:/Boost/boost/serialization/variant.hpp:69:75: warning: typedef 'types' locally defined but not used [-Wunused-local-typedefs] typedef typename boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>::types types; I looked up boost::ignore_unused, which says it's for unused types also, but everything I've tried for using in my code (following the definition of my variant) results in a syntax error or other bug claim. How should I use ignore_unused in this case?

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[Serialization] XML: float format is scientific instead of human-readable since Boost 1.57
by Frank Stähr 09 Feb '15

09 Feb '15

Hello Boost guys, when I switched from Boost 1.55 to 1.57 there was a change in the formation of floats and doubles for xml archives. Look at this example: #include <fstream> #include <boost/archive/xml_oarchive.hpp> class MyClass { friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & boost::serialization::make_nvp("accuracy", accuracy); } double accuracy = 0.03; }; int main() { MyClass obj; std::ofstream ofs("sample.xml"); boost::archive::xml_oarchive oa(ofs); oa & boost::serialization::make_nvp("myclass", obj); } I compiled it with VS 2013 for 32 bit. The output file has the line: <m_accuracy>2.99999999999999990e-002</m_accuracy> In Boost 1.55 it was much better human-readable: 0.03. Is this behaviour (this change) intended? In any case, what is the best way to format floats and doubles? (i. e. a manipulator for the ofstream?) Thanks, Frank -- Frank Stähr Technische Universität Berlin Communication Systems Group Sekr. EN1 Einsteinufer 17 10587 Berlin, Germany

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write starvation of upgradable lock
by David Frank 09 Feb '15

09 Feb '15

From this discussion, http://stackoverflow.com/questions/21773618/starvation-with-upgrade-lock?no… There seems to be a starvation of writer with upgradable lock, I'm wondering if there is any fix/improvement with later release, e.g, 1.56, or 1.57 Thanks,David

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[website] File appears truncated
by Joaquin M Lopez Munoz 07 Feb '15

07 Feb '15

The following file (which is linked from Boost.MultiIndex docs): http://www.boost.org/doc/libs/1_57_0/libs/multi_index/example/hashed.cpp appears truncated at line 8, yet it is perfectly OK in github: https://github.com/boostorg/multi_index/blob/master/example/hashed.cpp Any clue what's going on? Thank you, Joaquín M López Muñoz Telefónica

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[System] Link issues using BOOST_ERROR_CODE_HEADER_ONLY
by Jonathan Jones 07 Feb '15

07 Feb '15

Hello, We're in the process of upgrading from Boost 1.49 to Boost 1.56. As part of this upgrade, we've noticed the linkage requirements for using the "system" library are much more strict in 1.56. We are getting linker errors like the following across dozens of our libraries: boost/system/error_code.hpp: undefined reference to `boost::system::generic_category()' boost/system/error_code.hpp: undefined reference to `boost::system::system_category()' We decided to fix these by defining the macro BOOST_ERROR_CODE_HEADER_ONLY according to this link: http://www.boost.org/doc/libs/1_56_0/libs/system/doc/reference.html#Header- error_code However, when building Boost itself with this macro defined, we're encountering several problems: 1) Some Boost libraries (chrono, filesystem, random) that use the "system" library no longer link, as if they are still expecting the library to be present. Note that some libraries, like thread, that use "system", link fine without the shared library being present. 2) We get multiple definitions of "boost::system::throws" Any thoughts on how to resolve these? Google search has not turned up any bugs that I can find. Sincerely, Jonathan Jones

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[msm] multi thread access
by Sam Fisher 05 Feb '15

05 Feb '15

Hi Christophe, Did you consider adding build-in multi-thread support? (via policies maybe?) For example, I can guaranteed that all access to sub-fsm within its handlers (process_event()) will be synchronized. The problem is, sub-fsm "knows" about its parent and internally communicates with it (forwarding events etc). I can't control it from my side. typical scenario: an action from sub-fsm struct A_Init { template <typename Evt, typename FSM, typename SourceState, typename TargetState> void operator()(Evt&, FSM& fsm, SourceState&, TargetState&) const { std::thread([=]() mutable { std::lock_guard<std::mutex> l(access); fsm.process_event(some_event()); }).detach(); } }; locking proccess_event() in sub-fsm doesn't help if it alters the root.

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Using io_service for synchronous tcp accept + custom tasks
by Aaron Levy 04 Feb '15

04 Feb '15

I've written code of the form: Code: io_service svc; io_service::work work(svc); thread t1( [&svc]() { svc.run(); } ); thread t2( [&svc]() { svc.run(); } ); thread t3( [&svc]() { svc.run(); } ); endpoint ep(ip::tcp::v4(), port); acceptor acceptor(svc, ep); while (true) { shared_ptr<socket> sock(new socket(svc)); acceptor.accept(*sock); svc.post( [sock]() { /* do stuff on sock here */ }); } Is this way of using io_service for accepting tcp connections and also as a thread pool for serving connected clients valid or could I hit some undefined behavior. -- Aaron Levy aaron.levy(a)yandex.com

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joining boost ranges in loop
by Ernest Zaslavsky 04 Feb '15

04 Feb '15

Actually the question is how to achieve it? The use of boost::any_range is possible but undesirable (performance considerations) Sample code: typedef boost::multi_index_container< int, bmi::indexed_by<bmi::hashed_unique<bmi::tag<struct someTag>, bmi::identity<int>>>> Datum; class bar { public: auto foo() const; private: Datum m_someDataContainer; }; SomeType bar::foo() const { SomeType retVal; for (auto i = 0u; i < 10; ++i) { retVal = boost::range::join(retVal, m_someDataContainer.equal_range(i)); } return retVal; } Here we can observe several problems. The return type cannot be easily deduced. The join would create joined_range<joined_range<joined_range and so on of nested types. The above can be achieved by using any_range like typedef boost::any_range<int, boost::random_access_traversal_tag, int&, std::ptrdiff_t> VersionRange; but above will create nested joined_range of any_range which, when the number of iterations is big enough, has tremendous impact on performance. So, what can be done here?

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boost serialization + boost variant + boost blank
by Merrill Cornish 04 Feb '15

04 Feb '15

I'm running Boost 1.57.0 using serialization, variant, and boost::blank with that variant. I found that when compiled, serialization complains that blank does not contain a serialize method, which is true. I made a copy of blank.hpp, called it blank.h, and added template< class Archive > void serialize(Archive& ar, const unsigned int version) {} to the body of struct blank. That made the compiler happy, but is it a fix in general?

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[statechart] fifo_scheduler<>::operator() in state constructor
by Andrew C 04 Feb '15

04 Feb '15

Hi, is it allowed to call fifo_scheduler<>::operator() from state constructor? If yes, then let's assume "scheduler" and "processor" are objects of "fifo_scheduler<>" and "fifo_scheduler<>::processor_handle" types respectively in the some state constructor code below: State(my_context ctx): my_base(ctx) { boost::intrusive_ptr<Event> pEvent(new Event()); // If both lines [A] and [B] are uncommented // then "unconsumed_event" method is called twice. // If just line [A] is uncommented then "unconsumed_event" method is called. // If just line [B] is uncommented then certain "react" method is called. // scheduler.queue_event(processor, pEvent); // [A] // this->post_event(Event()); // [B] scheduler(); } Note constructor calls "scheduler()" at the end. Other questions: Is this code correct and runs expectedly as described in comments? Why "unconsumed_event" is called if use "queue_event" instead of "post_event"? Thanks, Andrew.

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Crashing Issue
by swati upadhyaya 03 Feb '15

03 Feb '15

In my code join() timed_joined() is crashing, I am using these API after interrupt(),Same piece of code is working for others but in my system its crashing, Is there some dependency problem I am using Boost version: 1.55.0 OS: Windows 8 IDE: Visual Studio 2010

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[Variant] Assertion fails at variant/detail/visitation_impl.hpp:207
by Attila Rajmund Nohl 02 Feb '15

02 Feb '15

Hello! I'm using boost-1.55 on Linux. When I run a specific testcase, I get an abort at line 207 in the visitation_impl.hpp file. The comment says that "should never be here at runtime". Unfortunately I don't really understand under what circumstances could runtime end up here - could someone explain how? The variant has a recursive element, i.e. looks something like this: struct Resp; struct SR { } struct AR { std::vector<Resp> resp; } typedef variant< SR, recursive_wrapper<AR> > RMType; struct Resp { RMType rm; }

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boost::ptr_container library question ?
by Danny K 02 Feb '15

02 Feb '15

The ptr_container supports an overload for std::auto_ptr<U>. I was curious if there was a way to add the same functionality for std::unique_ptr<U>. ie an overload that allows a std::unique_ptr to be added to a ptr_vector for example?

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[type_erasure] Problem with iterators
by Marco Guazzone 31 Jan '15

31 Jan '15

Hi, I'm new to the Type Erasure library. I need to write a base class with type-erased forward iterators. To do so I've taken inspiration from the print_sequence.cpp example I've found in the Type Erasure source tree. At the end of the email there is the whole code of my tentative, called "erasure.cpp". Unfortunately, I've problems (presumably) with const iterators which cause the following compile error: $ g++ -Wall -Wextra -pedantic -std=c++11 -I$HOME/sys/src/git/boost -o erasure erasure.cpp -lm *** [begin error] *** In file included from /home/sguazt/sys/src/git/boost/boost/type_erasure/iterator.hpp:20:0, from erasure.cpp:2: /home/sguazt/sys/src/git/boost/boost/type_erasure/operators.hpp: In instantiation of ‘static R boost::type_erasure::dereferenceable<R, T>::apply(const T&) [with R = double&; T = __gnu_cxx::__normal_iterator<const double*, std::vector<double> >]’: /home/sguazt/sys/src/git/boost/boost/type_erasure/detail/instantiate.hpp:91:9: required from ‘static void boost::type_erasure::detail::instantiate_concept7::apply(Concept*, Map*) [with Concept = boost::mpl::vector<boost::type_erasure::forward_iterator<>, boost::type_erasure::same_type<boost::type_erasure::deduced<boost::type_erasure::iterator_value_type<boost::type_erasure::_self> >, double>, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>; Map = boost::mpl::map1<boost::mpl::pair<boost::type_erasure::_self, __gnu_cxx::__normal_iterator<const double*, std::vector<double> > > >]’ /home/sguazt/sys/src/git/boost/boost/type_erasure/any.hpp:225:13: required from ‘boost::type_erasure::any<Concept, T>::any(U&&) [with U = __gnu_cxx::__normal_iterator<const double*, std::vector<double> >&; Concept = boost::mpl::vector<boost::type_erasure::forward_iterator<>, boost::type_erasure::same_type<boost::type_erasure::deduced<boost::type_erasure::iterator_value_type<boost::type_erasure::_self> >, double>, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>; T = boost::type_erasure::_self]’ erasure.cpp:36:40: required from ‘std::vector<_RealType> base<T>::foo(IterT, IterT) [with IterT = __gnu_cxx::__normal_iterator<const double*, std::vector<double> >; T = double]’ erasure.cpp:77:73: required from here /home/sguazt/sys/src/git/boost/boost/type_erasure/operators.hpp:134:44: error: invalid initialization of reference of type ‘double&’ from expression of type ‘const double’ static R apply(const T& arg) { return *arg; } *** [/end error] *** The GCC version is 4.9.2. Here below is the content of "erasure.cpp". If I comment lines below the comment "THE FOLLOWING WON'T COMPILE" I get no error. So the problem is due to the use of cbegin/cend. *** [erasure.cpp] *** #include <boost/type_erasure/any.hpp> #include <boost/type_erasure/iterator.hpp> #include <boost/type_erasure/operators.hpp> #include <boost/type_erasure/same_type.hpp> #include <boost/mpl/vector.hpp> #include <boost/smart_ptr.hpp> #include <cmath> #include <cstddef> #include <iostream> #include <iterator> #include <vector> namespace mpl = boost::mpl; namespace te = boost::type_erasure; template <typename T> using fwd_iter_impl_t = te::any< mpl::vector< te::forward_iterator<>, te::same_type<te::forward_iterator<>::value_type,T>>>; template <typename T> class base { protected: typedef fwd_iter_impl_t<T> fwd_iter_type; public: virtual ~base() { } template <typename IterT> std::vector<T> foo(IterT first, IterT last) { return this->do_foo(first, last); } private: virtual std::vector<T> do_foo(fwd_iter_type first, fwd_iter_type last) = 0; }; // base template <typename T> class derived: public base<T> { private: typedef typename base<T>::fwd_iter_type fwd_iter_type; std::vector<T> do_foo(fwd_iter_type first, fwd_iter_type last) { const std::ptrdiff_t n = std::distance(first, last); std::vector<T> res(n); for (std::size_t i = 0; first != last; ++first, ++i) { res[i] = std::pow(*first,i)/n; } return res; } }; // derived int main() { std::vector<double> dv; dv.push_back(5); dv.push_back(8); dv.push_back(11); boost::scoped_ptr< base<double> > p_base(new derived<double>()); // begin/end const std::vector<double> foos = p_base->foo(dv.begin(), dv.end()); for (std::size_t i = 0; i < foos.size(); ++i) { std::cout << "foos[" << i << "]: " << foos[i] << std::endl; } //--- THE FOLLOWING WON'T COMPILE // cbegin/cend const std::vector<double> cfoos = p_base->foo(dv.cbegin(), dv.cend()); for (std::size_t i = 0; i < cfoos.size(); ++i) { std::cout << "cfoos[" << i << "]: " << cfoos[i] << std::endl; } } *** [/erasure.cpp] *** Thank you very much for your help. Best, -- Marco

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[Asio] Handlers of asycn_send_to are called in which order?
by Attila Rajmund Nohl 30 Jan '15

30 Jan '15

Hello! My code sends UDP packets using async_send_to. If all packets are successfully sent, are their handlers called in the same order as the async_send_to calls happened? I mean if my code looks something like this: socket.async_send_to(buffer1, destination, handler1); socket.async_send_to(buffer2, destination, handler2); Is it guaranteed that handler2 is always called after handler1?

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