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generic vector
by U.Mutlu 17 Feb '15

17 Feb '15

Hi, I need to have a std::vector in my program, but it's type will be known only when it runs, ie. the type will be provided via a program param. The possible types are limited to these: int64_t, uint64_t, double, std::string. Is there a solution in boost or C++11 for this kind of problem? -- TIA Uenal

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[regex] problem w/ regex::extended
by U.Mutlu 16 Feb '15

16 Feb '15

Hi, the following regex expression works in perl-mode, but does not work in extented-mode. What's the reason? I think I haven't used any perl-specific construct, or did I? Where? ... #define NUM "[+-]?(\\d+\\.?\\d*|\\.\\d+)([eE][+-]?\\d+)?" #define WORD "[\\w\\-\\.~/]+" #define EQU "\\s*\\=\\s*" const string sUserRE_VarAndVal = WORD EQU NUM; #if 0 #define REGEX_ENGINE boost::regex::extended #else #define REGEX_ENGINE boost::regex::perl #endif regex reNum(sUserRE_VarAndVal, REGEX_ENGINE); ...

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[program options] option_groups.cpp example doesn't compile
by U.Mutlu 16 Feb '15

16 Feb '15

I've boost 1.55 from the debian repository. I'm trying to compile the below example of the 1.55 version (it's same as that of 1.57), but I get the following compile errors. Should I use some 'magic' compiler options, or what else is the reason for this grandious failure? $ g++ -Wall -std=gnu++11 option_groups.cpp -lboost_program_options option_groups.cpp: In function ‘int main(int, char**)’: option_groups.cpp:44:46: error: ‘class boost::program_options::typed_value<std::basic_string<char>, char>’ has no member named ‘implicit’ ("help-module", value<string>()->implicit(), ^ option_groups.cpp:96:11: error: reference to ‘exception’ is ambiguous catch(exception& e) { ^ In file included from /usr/include/c++/4.9/new:40:0, from /usr/include/c++/4.9/ext/new_allocator.h:33, from /usr/include/x86_64-linux-gnu/c++/4.9/bits/c++allocator.h:33, from /usr/include/c++/4.9/bits/allocator.h:46, from /usr/include/c++/4.9/string:41, from /usr/include/boost/program_options/errors.hpp:12, from /usr/include/boost/program_options/options_description.hpp:12, from option_groups.cpp:24: /usr/include/c++/4.9/exception:60:9: note: candidates are: class std::exception class exception ^ In file included from /usr/include/boost/throw_exception.hpp:43:0, from /usr/include/boost/any.hpp:26, from /usr/include/boost/program_options/value_semantic.hpp:12, from /usr/include/boost/program_options/options_description.hpp:13, from option_groups.cpp:24: /usr/include/boost/exception/exception.hpp:208:5: note: class boost::exception exception ^ option_groups.cpp:96:11: error: ‘exception’ does not name a type catch(exception& e) { ^ option_groups.cpp:97:17: error: ‘e’ was not declared in this scope cout << e.what() << "\n"; ^

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[context] boost::coroutines::asymmetric_coroutine<T>::pull_type iterator does not properly model InputIterator
by Mueller-Roemer, Johannes Sebastian 16 Feb '15

16 Feb '15

I’m currently on Boost 1.56 so this might have been fixed by now, but in a simple test Boost.Coroutine fails to properly model the InputIterator concept, because *it++ does not conform to the operational semantics { T tmp = *it; ++it; return tmp; } required by the standard. The failing program: #include <boost/coroutine/asymmetric_coroutine.hpp> #include <iostream> template<typename Continuation> auto foo(Continuation && yield) -> void { yield("Hello"); yield(", "); yield("World"); yield("!\n"); } //using T = char const *; using T = std::string; auto foo() -> boost::coroutines::asymmetric_coroutine<T>::pull_type { using namespace boost::coroutines; return asymmetric_coroutine<T>::pull_type{ [](asymmetric_coroutine<T>::push_type& yield) { foo(yield); } }; } auto main(int, char **) -> int { auto f = foo(); for(auto it = boost::begin(f); it != boost::end(f);) std::cout << *it++; } Which (on my machine) outputs: , World! X☺à r2 ` , ` , Ç2 Ç Failing to model the InputIterator concept is bad, because then it isn’t any kind of standards-conforming iterator at all. Interestingly, if T is char const * and not std::string the program works as expected. Is there some other subtle bug at work here? -- Johannes S. Mueller-Roemer, MSc Wiss. Mitarbeiter - Interactive Engineering Technologies (IET) Fraunhofer-Institut für Graphische Datenverarbeitung IGD Fraunhoferstr. 5 | 64283 Darmstadt | Germany Tel +49 6151 155-606 | Fax +49 6151 155-139 johannes.mueller-roemer(a)igd.fraunhofer.de | www.igd.fraunhofer.de

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Strange boost::threads behaviour
by Lorenzo Trivelli 16 Feb '15

16 Feb '15

Hi to everyone, first of all thanks to all the people who writes and manteins this wondefrul collection of libraries ;-) While analyzing a resource exaustion problem on a production machine, (Windows) I found out astrange behaviour of boost::threads regarding event object. The problem is that after a certain number of iterations it semms that the thread lib allocates an EventHandle which is never freed. I managed to reproduce in some ways the behaviour, but I'm a bit clueless about its reason. To be honest, the amount of handles "leaked" by the test code is quite less than the amount I found on production server, but test code is also quite simpler. Now some info: 1) OS: Win 2033 , Win 2008 2) I tested it with both 1.46.1 and 1.57.0, compiled using stlport using VS2005 3) if you want I can attach the sample code with a but if info on how to reproduce the behaviour thanks in advance L. Trivelli

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[future] Confused about the represents in Doc "boost::future"
by Cheng Mo 16 Feb '15

16 Feb '15

Hi all : I got confused in Doc of boost :: futures and I can't got the point of sort of terms. The represents in Overvies of Futures like " Instances can be freely copied and assigned, and boost::shared_future<R>::get() returns a non const reference so that multiple calls to boost::shared_future<R>::get() are safe." no doubt that a const reference .... are safe. a non const reference could be changed by external stimuli. isn't ? Or the key is "Instances can be freely copied" , so that we can say "are safe"? Cheer~ Martin

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[program options] examples where?
by U.Mutlu 15 Feb '15

15 Feb '15

In the online documentation tutorial there are multiple times mentioned references to the examples page. But where are these examples exactly located? On the documentation pages I couldn't find a link to the examples page. Do I need to install the complete boost developer version locally to get to the examples? -- cu Uenal

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[program options] an alternative for "add_options()" avail?
by U.Mutlu 15 Feb '15

15 Feb '15

Hi, I'm newbie to 'program options'. I just wanted to ask if there is an alternative for the below example from the online-doc: desc.add_options() ("help", "produce help message") ("compression", po::value<int>(), "set compression level") ; I would like to have something more traditional like the following single element addition alternative: desc.add_option("help", "produce help message"); desc.add_option("compression", po::value<int>(), "set compression level"); Is something like this already in the library? -- TIA Uenal

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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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