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[container] Compilation failure with clang 3.1
by Alexandre Hamez 25 May '12

25 May '12

Hello, When compiling Boost.Container, clang 3.1 (stable release, Mac OS X 10.7.4) fails: > /opt/local/include/boost/container/allocator/allocator_traits.hpp:167:105: >> error: type name requires a specifier or qualifier > > template <typename T> using rebind_alloc = >> boost::intrusive::detail::type_rebinder<Alloc, T>::type; > > >> ^ > > /opt/local/include/boost/container/allocator/allocator_traits.hpp:167:59: >> error: expected ';' after alias declaration > > template <typename T> using rebind_alloc = >> boost::intrusive::detail::type_rebinder<Alloc, T>::type; > > ^ > > ; > > /opt/local/include/boost/container/allocator/allocator_traits.hpp:168:72: >> error: use of undeclared identifier 'rebind_alloc' > > template <typename T> using rebind_traits = allocator_traits< >> rebind_alloc<T> >; > > ^ > > /opt/local/include/boost/container/allocator/allocator_traits.hpp:168:85: >> error: 'T' does not refer to a value > > template <typename T> using rebind_traits = allocator_traits< >> rebind_alloc<T> >; > > >> ^ > > /opt/local/include/boost/container/allocator/allocator_traits.hpp:168:29: >> note: declared here > > template <typename T> using rebind_traits = allocator_traits< >> rebind_alloc<T> >; > > ^ > > /opt/local/include/boost/container/allocator/allocator_traits.hpp:168:87: >> error: expected ';' after alias declaration > > template <typename T> using rebind_traits = allocator_traits< >> rebind_alloc<T> >; > > However gcc 4.7 has no problem with it. Does anyone has experienced the same thing and possibly found a workaround? Thank you! Alexandre Hamez

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Spirit, StateChart, MSM
by asif saeed 25 May '12

25 May '12

Hi, What are the differences between these three libraries? I feel I can use any of these libs. Is there any page where the comparison/pros&cons are listed and so on? Best regards, Asif

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[msm] Two identical orthogonal regions?
by Aurelian Melinte 25 May '12

25 May '12

Hi, I am trying to put two identical orthogonal regions in a state machine (each region would model a "channel" and I can have multiple such channels). One way I can think of is duplicating the states through typedefs and duplicating entries in the transition table. Is there a way to avoid this duplication? Regards, a.

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[Geometry] spatial linestring access along line
by Stephan Menzel 25 May '12

25 May '12

Hi all, before I begin, let me tell that geometry is not exactly my strong suite so please forgive my probably dumb question. I have started to work with boost geometry which, I find very neat, and assembled a line string. Now I basically need a method that gives me a point to a length value. Like when my linestring is 100 units long and I say give me the point at 3 I want the exact position of the point (coordinates) as if I were following the line for exactly 3 units. I have an approach that would allow me to implement this myself by following the segments (possibly after indexing them) but I have a feeling that one of those many functions provided by the library itself might do just that and I simply don't know it. If anyone knows if such is the case, would be nice to give me a heads up. Thanks, Stephan

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[multi_index] movable only types
by Szymon Gatner 25 May '12

25 May '12

Hi, with boost.move available are there any plans to make multi_index work with movable-only types? -- Szymon Gatner The Lordz Games Studio www.thelordzgamesstudio.com

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offlist - Re: [iterator] Problems with iterator_facade and const-qualification
by Neil Groves 24 May '12

24 May '12

On Sat, May 7, 2011 at 5:52 PM, Dave Abrahams <dave(a)boostpro.com> wrote: > On Fri, May 6, 2011 at 1:51 PM, Evan Driscoll <driscoll(a)cs.wisc.edu> > wrote: > > On 05/06/2011 11:59 AM, Jeff Flinn wrote: > >> > >> You might google any_iterator, and see how other authors have addressed > >> similar problems. > > > > Great! I tried to find someone who had done something similar, figuring I > > couldn't have been the first, but all the search terms I tried were too > > generic. > > > > Thanks, > > Evan > > You can find one in the ASL that's built on iterator_facade. > http://stlab.adobe.com/classadobe_1_1any__iterator.html > > The underlying Boost.Range implementation implements an any_iterator that I believe to be similar to the one in ASL in terms of functionality. I believe that the small-buffer optimization implementation is superior to forcing the definition of a closed-set of possible type as suggested in a TODO within the ASL documentation. During my performance testing I had considerably superior performance than the ASL implementation. I wondered if you disliked my implementation, or had any feedback. Additionally I wondered what you thought about moving the Boost.Range internal any_iterator implementation into Boost.Iterator. I can't honestly imagine a good use-case for using any_iterator in preference to any_range, hence I haven't suggested this previously. This could easily be due to my lack of imagination! Can you think of a time when using an any_iterator on any interface would be superior to using an any_range? Your opinions and guidance would be much appreciated. HTH, > > -- > Dave Abrahams > BoostPro Computing > http://www.boostpro.com Regards, Neil Groves

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Iterator concept checking
by McNamara, Nate 24 May '12

24 May '12

I'm trying to learn to use BOOST_CONCEPT_CHECK for custom iterators, ranges, and containers. I've built a simple linked list class with an iterator (and const_iterator) that, as far as I can tell, satisfies the forward traversal iterator requirements. However, g++ gives the following errors: concept.cpp:81: error: `*' cannot appear in a constant-expression concept.cpp:81: error: a call to a constructor cannot appear in a constant-expression concept.cpp:81: error: template argument 1 is invalid concept.cpp:81: error: template argument 1 is invalid concept.cpp:82: error: `*' cannot appear in a constant-expression concept.cpp:82: error: a call to a constructor cannot appear in a constant-expression concept.cpp:82: error: template argument 1 is invalid concept.cpp:82: error: template argument 1 is invalid concept.cpp:83: error: `*' cannot appear in a constant-expression concept.cpp:83: error: a call to a constructor cannot appear in a constant-expression concept.cpp:83: error: template argument 1 is invalid concept.cpp:83: error: template argument 1 is invalid concept.cpp:84: error: `*' cannot appear in a constant-expression concept.cpp:84: error: a call to a constructor cannot appear in a constant-expression concept.cpp:84: error: template argument 1 is invalid concept.cpp:84: error: template argument 1 is invalid Compiling with -E, lines 81-84 are as follows: typedef ::boost::concepts::detail::instantiate< &::boost::concepts::requirement_<void(*)(boost::concepts::ForwardTravers alIterator<iterator>)>::failed> boost_concept_check81; typedef ::boost::concepts::detail::instantiate< &::boost::concepts::requirement_<void(*)(boost::concepts::WritableIterat or<iterator>)>::failed> boost_concept_check82; typedef ::boost::concepts::detail::instantiate< &::boost::concepts::requirement_<void(*)(boost::concepts::ForwardTravers alIterator<const_iterator>)>::failed> boost_concept_check83; typedef ::boost::concepts::detail::instantiate< &::boost::concepts::requirement_<void(*)(boost::concepts::ReadableIterat or<const_iterator>)>::failed> boost_concept_check84; That tells me that, regardless of why g++ is having trouble, my iterator fails to satisfy the concept somehow. So I wrote some code (see my_naive_check, below) to try to figure out which requirement is failing, but my check code is missing the same thing as the iterator, because the check code runs fine. Any pointers much appreciated. // concept.cpp // What's wrong with the iterators? #include <cassert> #include <cstdlib> #include <iostream> #include <string> #include <boost/concept_check.hpp> #include <boost/iterator/iterator_concepts.hpp> #include <boost/iterator/iterator_facade.hpp> #include <boost/lambda/lambda.hpp> #include <boost/range/algorithm.hpp> template <typename T> class List { struct Node { Node(const T& value_, Node *next_): value(value_), next(next_) {} T value; Node *next; } *head; public: List(): head(0) {} ~List() { Node *node = head; while (node) { Node *tmp = node->next; delete node; node = tmp; } } void push_front(const T& value) { head = new Node(value, head); } class iterator: public boost::iterator_facade<iterator, T, boost::forward_traversal_tag> { public: iterator(): node(0) {} private: iterator(Node * const node_): node(node_) {} friend class List; friend class boost::iterator_core_access; T& dereference() const { return node->value; } bool equal(const iterator& rhs) const { return node == rhs.node; } void increment() { node = node->next; } Node *node; }; iterator begin() { return iterator(head); } iterator end() { return iterator(); } class const_iterator: public boost::iterator_facade<const_iterator, const T, boost::forward_traversal_tag> { public: const_iterator(): node(0) {} const_iterator(const iterator& old): node(old.node) {} private: friend class boost::iterator_core_access; const T& dereference() const { return node->value; } bool equal(const const_iterator& rhs) const { return node == rhs.node; } void increment() { node = node->next; } const Node *node; }; const_iterator begin() const { return const_iterator(head); } const_iterator end() const { return const_iterator(); } BOOST_CONCEPT_ASSERT((boost::concepts::ForwardTraversalIterator<iterator >)); BOOST_CONCEPT_ASSERT((boost::concepts::WritableIterator<iterator>)); BOOST_CONCEPT_ASSERT((boost::concepts::ForwardTraversalIterator<const_it erator>)); BOOST_CONCEPT_ASSERT((boost::concepts::ReadableIterator<const_iterator>) ); }; /* ForwardTraversalIterator must be SinglePassIterator IncrementableIterator Assignable Copy Constructible &r == &++r r++ *r++ == != difference_type DefaultConstructible iterator_traversal<X>::type => forward_traversal_tag */ void my_naive_check(List<std::string>& words) { typedef List<std::string>::iterator It; It it1 = words.end(); it1 = words.begin(); &it1 == &++it1; It it2 = it1++; std::string word = *it2++; assert(it1 == it2); assert(words.begin() != words.end()); It::difference_type distance = 0; It it3; boost::forward_traversal_tag tag = boost::iterator_traversal<It>::type(); } int main() { List<std::string> words; words.push_front("world"); words.push_front("Hello"); my_naive_check(words); boost::for_each(words, std::cout << boost::lambda::_1 << "\n"); return EXIT_SUCCESS; } ________________________________________ This E-Mail (including any attachments) may contain privileged or confidential information. 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boost::asio one connectio-per-thread
by Christer Borgqvist 24 May '12

24 May '12

Hello, is this a code appropriate? boost::asio::io_service io_service; tcp::acceptor a(io_service, tcp::endpoint(tcp::v4(),3080)); for (;;) { socket_ptr sock(new tcp::socket(io_service)); a.accept(*sock); emv_clientthread_ptr cli(new axf::server::server_socket(sock)); boost::thread t(boost::bind(&axf::server::server_socket::start, cli)); } appreciate any help. Christer

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[Chrono] Negative real time
by Wilfried Kirschenmann 23 May '12

23 May '12

Dear chrono maintainer team, Using the following example : int main(int argc, char **argv) { boost::chrono::process_real_cpu_clock::time_point start = boost::chrono::process_real_cpu_clock::now(); for ( long i = 0; i < 1000; ++i ) std::sqrt( 123.456L ); // burn some time Sleep(10000); //idle some time boost::chrono::process_real_cpu_clock::time_point end = boost::chrono::process_real_cpu_clock::now(); std::cout << end << std::endl; boost::chrono::process_real_cpu_clock::duration elapsed = (end - start); std::cout << "took real : " << elapsed << "nanoseconds\n"; return 0; } I obtain negative times. I run boost 1.49 win32 on Windows 7 x64 with Visual studio 2010. Studying the behavior of the timer, I think that the error is one of these : - process_real_cpu_clock::now() only stores the current time in a 32 bit integer instead of a 64 bit integer - time_points only prints the 32 lowest bits. I came to this conclusion by observing the results printed before they got negatives (printing in the loop with the sqrt): 2019000000 nanoseconds is the last value printed before getting negative. Is there any mistake in my way of using this chronometer ? Do you have a workaround ? Thank you for your help ! Wilfried K. ----- Cordialement, Wilfried Kirschenmann "An expert is a person who has made all the mistakes that can be made in a very narrow field."* *Niels Bohr - *Danish physicist (1885 - 1962)*

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boost::serialization "input stream error" in release-build (msvc2010)
by Jens Saathoff 23 May '12

23 May '12

Hi! I'm using boost::serialization to save a structure to a file and read from a file. My code works perfect in debug-build, but in release-build an exception is thrown. I'm using MSVC2010 to build the project on Windows 7 64-Bit-Machine. The code is the same. Who could help me out? You can find the code here: http://boost.codepad.org/8fp6XnC3 Thank you very much!!!!

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