May 2013 - Boost-users - lists.preview.boost.org

[asio] schedule work on all threads of a single io_service::run() pool?
by Anthony Foiani 18 May '13

18 May '13

Greetings -- Is there a way to ask the io_service to distribute a particular handler to every thread that is running the service? My use case is per-thread watchdogs, and I need the worker threads to ping the watchdog on some regular interval (e.g., every 5 seconds). I didn't see anything like this in the docs, and I didn't see anything that looked promising when I looked through the source. (I'll freely admit that the ASIO source is beyond my ability to comprehend it without much more study, however.) I can approximate it by having my worker threads do something like this (pseudocode): while ( true ) { boost::system::error_code ec; io_service::poll_one( ec ); if ( ec == stopped ) break; watchdog::ping(); sleep( 500ms ); // trying to balance lag and wakeups } But that has the obvious problems of lag and more wakeups than I really need. To make this hack work, I think I need some calls that probably don't exist; instead of that "sleep" call, I would like to be able to do something like a timed wait on a condition variable: io_service::all_threads_cond.timed_wait( 5s ); That way, I would only wake up every 5 seconds (to feed the watchdog), unless the io_service sent a "notify_one" to the condition variable and this thread happened to be picked. Extra pings aren't much of an issue, but it would be nice to minimize them. Anyway. I'll continue digging, but if anyone has suggestions, I'd love to hear them. Thanks in advance! Best regards, Anthony Foiani

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[smart_ptr] Migrating from boost::shared_ptr<> to std::shared_ptr<>
by Szymon Gatner 18 May '13

18 May '13

Hi, with recently acquired (semi) C++11 compiler (YEY!) I started to think which of BOOST functionality could be replaced by standard counterparts. First obvious candidates are smart pointers. Thing is, there is lots of functions that take boost::shared_ptr<> as arguments (or return them) and it is just not easy to do do. My questions: - does it even make sense to switch to std::shared_ptr<> (should new functions use std instead of boost) - is there a way to easily convert one to another - what are (if any) differences between std and boost versions Regards, Szymon Gatner

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(no subject)
by Yeni Lora 18 May '13

18 May '13

Hi I have a problem with my code I using mpi. The error is with mca_btl_tcp_frag_recv, and I don´t know what mean... The error complete [../../../../../../ompi/mca/btl/tcp/btl_tcp_frag.c:216:mca_btl_tcp_frag_recv] mca_btl_tcp_frag_recv: readv failed: Connection timed out (110) and [btl_tcp_frag.c:216:mca_btl_tcp_frag_recv] mca_btl_tcp_frag_recv: readv failed: Connection reset by peer (104) I need some help...

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[lockfree] overwriting push?
by Rich E 18 May '13

18 May '13

I'm using boost::lockfree::spsc_queue in an audio graph to allow audio input samples written from one thread to be read from another. This currently looks like: #include <boost/lockfree/spsc_queue.hpp> class RingBuffer { public: RingBuffer() : mLockFreeQueue( 0 ) {} RingBuffer( size_t size ) : mLockFreeQueue( size + 1 ), mSize( size ) {} ~RingBuffer() {} //! pushes to buffer, overwriting oldest samples void write( const float *samples, size_t count ) { if( count > mSize ) { count = mSize; } size_t numPushed = mLockFreeQueue.push( samples, count ); if( count > numPushed ) { size_t numLeft = count - numPushed; // ???: is there a more efficient way to overwrite? float old; for( int i = 0; i < numLeft; i++ ) { mLockFreeQueue.pop( old ); } numPushed = mLockFreeQueue.push( &samples[numPushed], numLeft ); assert( numPushed == numLeft ); } } size_t read( float *samples, size_t count ) { if( count > mSize ) { count = mSize; } return mLockFreeQueue.pop( samples, count ); } private: boost::lockfree::spsc_queue<float> mLockFreeQueue; size_t mSize; }; If there is not enough space in the write call, I sequentially pop off elements until there is enough. Is there a better way to do this? It seems like there should be a mechanism for just moving the read head forward (atomically) without reading anything, but then I am not sure I completely understand the implications of that on the lockfree model. I'm also not 100% sure this is adhering to the lockfree model, so please inform me if/how it isn't if you know. Thank you for your time, Rich

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[BGL] assert( source(* (out_edges(v, undigraph).first), undigraph) == v )
by Andreas Fabri 17 May '13

17 May '13

Hello, When I have an undirected graph, for edge_descriptor source and target still are defined. That is stated here: http://www.boost.org/doc/libs/1_53_0/libs/graph/doc/graph_concepts.html My question. Is edge_descriptor ed = * out_edges(v,undigraph).first; Is there a requirement for graph implementations that source(ed,g) == v ? best regards, andreas -- Andreas Fabri, PhD Chief Officer, GeometryFactory Editor, The CGAL Project phone: +33.492.954.912 skype: andreas.fabri

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which library to use:cleaning up singletons
by Littlefield, Tyler 17 May '13

17 May '13

hello all: I have a fairly large code base that has a lot of modules and systems. The problem is that I have a main "engine" object that holds pointers to a lot of created modules and components. I'm trying to find a more dynamic way to do this, and I thought boost might be able to help. As a result, I have a couple of questions. First, I do a lot of manual adding of features. For example, when I add a new command I have to add a engine->commands.AddCommand(new CMDFoo()); in an initialization method. Does boost provide some sort of mechenism for dynamically handling this? I also plan on splitting up the main "engine" object and setting up the external modules as singletons. They act alone, but again I'd like to dynamically initialize these. Is there a way on entry to dynamically call specific singleton initialization methods, then at exit call their release methods? I'd like to be able to set some sort of trait on these objects at compile-time that the runtime can use, or somehow generate the calls at compile-time. Thanks in advance for any info, -- Take care, Ty http://tds-solutions.net He that will not reason is a bigot; he that cannot reason is a fool; he that dares not reason is a slave. Sent from my Toaster (tm).

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[Boost.Atomic] Wait-free multi-producer queue example bug?
by Ioannis Papadopoulos 16 May '13

16 May '13

Hi, In http://www.boost.org/doc/libs/1_53_0/doc/html/atomic/usage_examples.html#bo… I see that pop_all_reverse() is implemented as: node * pop_all_reverse(void) { return head_.exchange(0, boost::memory_order_consume); } Shouldn't the memory order be memory_order_acquire in this example? If I'm not mistaken, at least an acquire is required to see all the writes from the thread that did the release. GCC 4.8 also complains that memory_order_consume is not a correct memory ordering for exchange. Thanks

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[Graph] Problem with large vertex ids
by Stephen Woodbridge 16 May '13

16 May '13

Hi all, I'm trying to understand/fix some bugs in pgRouting that use the boost libraries. I know C not not C++, so I can understand most of the more C-ish parts. We have an old bug that I believe is caused when we add an edge and it has large vertex ids or when there is a large number between the min and max vertex numbers. We currently identify the min id number and down shift the ids by that, but that does not help if I add an edge (1)->(100000000). I could renumber all the nodes and then un-renumber them when done if I have to. Questions: 1. is this a known limitiation in Boost graph? 2. is there a different type of adjacency list mechanism that does not have this issue 3. currently the code crashes the database backend, ideally I would like to catch any issues in the C++ wrapper, free memory and return an error code to the C caller so we don't kill the server or leak lots of memory. Here is a link to our boost wrapper code: https://github.com/pgRouting/pgrouting/blob/sew-devel-2_0/src/dijkstra/src/… We use that pattern for a lot of functions so if there is a better pattern, I might be able to update most(all?) of the functions that use this. I could really use some help resolving this issue. Meanwhile, I'm off to write a C main() to run this outside of the database and in gdb to see whats happening. Thanks, -Steve, trying to release pgRouting 2.0

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Interprocess : vectors of vectors
by Oodini 16 May '13

16 May '13

Hello, I'd like to share a vector of vectors (jagged 2D array). The data come from a deserialization. I know the size of the "external" vector. The sizes of the "internal" vectors are discovered during deserialization. I read : http://www.boost.org/doc/libs/1_52_0/doc/html/interprocess/quick_guide.html… and regarding this line : managed_shared_memory segment(create_only, "MySharedMemory", //segment name 65536); how to set the size (3rd argument), when considering my use case ? Even with a simple vector, and if the number and the types of the elements are know? i woldn't know what size to set for truncation. On VS 2010, a sizeof(vector<int>) is 40; I suppose I have to add it sizeof(int)*nbElements to get the full size. 1. I don't know if this assumption is valid 2. If so, I don't know if it's still valid when using Boost.Interprocess (I suppose it isn't) 3. I don't know how to generalize that to a vector of vectors in order what should be the truncation size. Thanks for help. PS : I also read http://www.boost.org/doc/libs/1_52_0/doc/html/interprocess/managed_memory_s…, but I havn't been enlightened about these points.

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Interprocess : offset_ptr used as array
by Oodini 16 May '13

16 May '13

Hello, I have an offset_ptr named tmpData defined like this : offset_ptr<const byte>* someVariable; indextype index; ... offset_ptr<const byte> tmpData = ((offset_ptr<const byte>*)someVariable)[index]; data points actually to the beginning of an array. The original code, without shared memory was : byte* data= ((byte**)m_someVariable)[index]; The problem is that I have to translate that : indextype* data = (indextype*)&(tmpData[1]); The adress of the second element is taken though the & adress. But when tmpData is an offset_ptr, the [] operator returns a reference, and I can apply the & operator. Is there any solution that copying the pointer to temporary variable, and increment this one ? Thanks.

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Re: [Boost-users] boost::variant & c++11
by Antony Polukhin 16 May '13

16 May '13

2013/5/15 Bryan Catanzaro <bcatanzaro(a)acm.org>: > Hi Antony - > Perhaps it is compiler dependent. Which version of MSVC did you reproduce > the error with? Does that version have c++11 support enabled (in particular, > rvalue references) > As I said, with Boost 1.48.0, this code works with g++ 4.6 and 4.7. With > 1.53.0, it works with g++ 4.6 and 4.7 only if c++11 support is turned off. > If c++11 support is turned on, the code does not work. > I've attached a shell script that compiles the attached code with the cross > product of {(g++4.6, g++4.7), (boost1.48, boost1.53), (noc++11, yesc++11)}. > As you can see from test.txt, the error happens only with boost 1.53 and > c++11 support. > > > - bryan Exactly the same things happen on GCC-4.5 and Clang-3.0. But what is more interesting here: convertible c; const convertible& cc = c; // Always compiles, using any flags, compiler and Boost version my_variant y = cc; my_variant y1 = static_cast<const convertible&>(c); my_variant y2 = static_cast<const convertible>(c); // Always fail to compile, using any flags and Boost version // my_variant z = c; // my_variant y3 = static_cast<convertible&>(c); Tested on clang, gcc4.5, gcc 4.6, gcc4.7 on Boost 1.48 and Boost 1.53 with and without C++11 flags. If we modify `convertible`: struct convertible { operator my_variant() { return my_variant(); } operator my_variant() const { return my_variant(); } }; Then ALL the tests pass well, even the commented out ones. Even `my_variant y4 = static_cast<convertible&&>(c);` works well. I'll test it tomorrow on Visual Studio 11 once more and investigate issue futher. -- Best regards, Antony Polukhin

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PROBLEM WITH BOOST MPI
by siva teja 15 May '13

15 May '13

Hi friends, I have to run distributed_delta_stepping with graphs in CSR fromat. So I tried with "distributed_shortest_path_test.cpp" located at "<top of boost source tree>/libs/graph_parallel/test/ ". It reads a random graph in adjacency list format. But I have to run DIMACS_USA graph in CSR format. So, I edited the code but it resulted in following errors. I guess I am facing problems while representing a graph in CSR format.. CODE : void test_distributed_shortest_paths(int n, double p, int c, int seed) { char *graf = "./dimacs_USA_sort_wdup" ; typedef compressed_sparse_row_graph<directedS, VertexProperties, WeightedEdge, no_property, distributedS<mpi_process_group> > Graph; typedef graph_traits<Graph>::vertex_descriptor vertex_descriptor; typedef graph_traits<Graph>::edge_descriptor edge_descriptor; typedef graph_traits<Graph>::vertex_iterator vertex_iterator; typedef graph_traits<Graph>::vertices_size_type vertices_size_type; typedef property_map<Graph, vertex_index_t>::type vertex_index_map; typedef std::pair<long int, long int> Edge; struct timeval starttime,endtime,timediff; gettimeofday(&starttime,0x0); char ch; long int num_nodes; long int num_arcs; Edge *edge_array; long int *weights; long int arc_index=0, wt_index=0; long int vert1, vert2, dist; std::fstream input; input.open(graf); if( !input.eof()) { input >> ch; if(ch == 'vertex') { input >> num_nodes; } } if(!input.eof()) { input >> ch; if(ch =='edge') { input >> num_arcs; } else std::cout << "Wrong graph format\n"; } edge_array=(Edge *)malloc(sizeof(Edge) * num_arcs); weights=(long int *)malloc(sizeof(long int) * num_arcs); while(!input.eof()) { input >> ch; if(ch == 'arc') { input >> vert1 >> vert2 >> dist; Edge temp; temp.first=vert1; temp.second=vert2; edge_array[arc_index++]=temp; weights[wt_index++]=dist; } } gettimeofday(&endtime, 0x0); Graph g(edge_array, edge_array + num_arcs, weights, num_nodes); vertex_descriptor s = vertex(1, g); graph::distributed::delta_stepping_shortest_paths(g, s, dummy_property_map(), get(&VertexProperties::distance, g), get(&WeightedEdge::weight, g)); } But when I run the command " mpirun -np 1 ./a.out" I face the following errors. **** Testing aborted. **** 1 error detected ------------------------------ -------------------------------------------- mpirun has exited due to process rank 0 with PID 19096 on node rise-02 exiting without calling "finalize". This may have caused other processes in the application to be terminated by signals sent by mpirun (as reported here). -------------------------------------------------------------------------- Thank you in advance.

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Statechart timer extension and new version of visualizer
by Petr Silhavik 15 May '13

15 May '13

Hi, I have implemented timers for library Boost Statechart. It was tested only on Linux because it uses POSIX threads. It is extension that replaces fifo_scheduler and fifo_worker with only one class Scheduler. That means that it is suitable only for asynchronous state machines. The source codes with example and short description can be downloaded here: https://www.dropbox.com/s/ubtep8f7hs6g5xl/boostTimers.tar.gz I would like to also inform you about new version of Boost Statechart viewer. Now it is plugin for compiler Clang and it was tested vitw version 3.0 and higher - (mostly tested using version 3.1). You can find more information and news about it on the web page of this project where you can also download the source codes and see some examples of the output pictures. http://rtime.felk.cvut.cz/statechart-viewer/ Best regards Petr

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boost::variant & c++11
by Bryan Catanzaro 15 May '13

15 May '13

Hi - I seem to have run into a regression with boost::variant from 1.48 to 1.53. With C++11 enabled, using g++, the following code seems to confuse variant's constructor selection machinery: if you look at the line after #ifndef WAR, the implicit conversion isn't happening, and so boost::variant attempts to convert construct from extract<my_variant> to A or B. It should instead copy construct from the output of extract<my_variant>'s implicit conversion to my_variant. If I force an explicit conversion, this problem doesn't occur. If I don't enable c++11, this problem doesn't occur. With Boost 1.48, this problem doesn't occur. Any advice from the list as to why this behavior changed? Thanks, bryan #include <boost/variant.hpp> //A simplified wrapper template<typename T> struct wrap { T t; wrap(T& _t) : t(_t) {} operator T() const { return t; } T force() const { return t; } }; struct A{}; struct B{}; typedef boost::variant<A, B> my_variant; int main() { A a; my_variant x(a); #ifndef WAR my_variant y = wrap<my_variant>(x); #else my_variant y = wrap<my_variant>(x).force(); #endif } And the error: /home/bcatanzaro/boost_1_53_0/boost/variant/variant.hpp:1574:9: error: no matching function for call to ‘boost::variant<A, B>::initializer::initialize(void*, std::remove_reference<wrap<boost::variant<A, B> >&>::type)’

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Constraining unordered template constructors
by Michael Marcin 15 May '13

15 May '13

I have a class that I want to have accept 0-5 arguments in any order for it's constructor. Each argument is a const references to one of 5 possible class types. All arguments must be distinct in type, passing the same type twice in an error. Passing an argument that is not one of the 5 supported types is also an error. How do you go about implementing something like this? I figure first you have to create a constructor for each arity but then how do you constrain the constructors as described above? I imagine it would involve enable_if. class widget { widget(); template< class A > widget( const A& a ); template< class A, class B > widget( const A& a, const B& b ); template< class A, class B, class C > widget( const A& a, const B& b, const C& c ); template< class A, class B, class C, class D > widget( const A& a, const B& b, const C& c, const D& d ); template< class A, class B, class C, class D, class E > widget( const A& a, const B& b, const C& c, const D& d, const E& e ); };

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directory monitoring with dynamically added dirs
by Richard Langly 14 May '13

14 May '13

I'm trying to dynamically add directories from a config file before I enter my programs main loop using the ASIO dir monitor example. I've not been able to understand the internals yet. Below is my current iteration of what I'm trying. I have been able to get the simple examples running just like in the async.cpp file. But I can't get adding dirs dynamically working and was hoping someone could offer suggestions. Any help much appreciated. void my_file_handler(const boost::system::error_code &ec, const boost::asio::dir_monitor_event &ev) { // event stuff ... return; } boost::asio::dir_monitor *dm; boost::asio::io_service io_service; vector<boost::asio::dir_monitor *> vecdm; for (vector<Directories>::iterator it = dirs->begin(); it != dirs->end(); ++it) { dm = new boost::asio::dir_monitor(io_service); dm->add_directory((*it).abs_dir_path); vecdm.push_back(dm); } boost::thread t = boost::thread(boost::bind(&boost::asio::io_service::run, boost::ref(io_service))); while (true) { // MAIN PROGRAM LOOP for (vector<boost::asio::dir_monitor *>::iterator it = vecdm.begin(); it != vecdm.end(); ++it) { (*it)->async_monitor(my_file_handler); } io_service.reset(); // DO PROGRAM STUFF ... } ~ ~

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[msm] Injecting events to FSMs from different translation units
by samriti katoch 14 May '13

14 May '13

Hi, I am using boost msm to design state machines for a relatively large project. The documentation online is pretty good and I was able to figure out most features by looking at the sample code (thanks!). My particular application has multiple FSM instances active at any given time, and what I would like to do is to be able to generate events for a particular FSM instance from different translation units. But I'd like to keep the the compile time at a minimum. I found an answer from Christophe for a similar question sometime back here: http://stackoverflow.com/questions/10899641/boost-msm-class Since, I have multiple FSM instances it would not help to have a singleton class with the FSM shared_ptr. I am looking for ideas/suggestions/experiences for implementing this in an elegant OO ways. Thanks, Samriti

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CANNOT COMPILE BOOST 153 WITH GCC-4.8
by Didier J-P Guion Firmin 14 May '13

14 May '13

Hi guys, I've tried to compile boost 153 with gcc-4.8 and two weird things are happening. 1 - a bunch of warning during compile time 2 - any program using boost thread errors out : Threading support unavaliable: it has been explicitly disabled with BOOST_DISABLE_THREADS" Can you please help me figure out what I'm doing wrong Thank you --

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boost::addressof and std::nullptr_t
by Mathieu Champlon 12 May '13

12 May '13

Hello, With MSVC 2010 the following code fails to compile : std::nullptr_t np; boost::addressof( np ); The error being : 1>....\boost/utility/addressof.hpp(59): error C2666: 'boost::detail::addressof_impl<T>::f' : 2 overloads have similar conversions 1> with 1> [ 1> T=std::nullptr_t 1> ] 1> ....\boost/utility/addressof.hpp(43): could be 'std::nullptr_t *boost::detail::addressof_impl<T>::f(T *,int)' 1> with 1> [ 1> T=std::nullptr_t 1> ] 1> ....\boost/utility/addressof.hpp(37): or 'std::nullptr_t *boost::detail::addressof_impl<T>::f(T &,long)' 1> with 1> [ 1> T=std::nullptr_t 1> ] 1> while trying to match the argument list '(boost::detail::addr_impl_ref<T>, int)' 1> with 1> [ 1> T=std::nullptr_t 1> ] 1> ....blabla.cpp(356) : see reference to function template instantiation 'T *boost::addressof<std::nullptr_t>(T &)' being compiled 1> with 1> [ 1> T=std::nullptr_t 1> ] Can this be considered a bug in boost::addressof ? As a side note it compiles with std::addressof which implementation for MSVC 2010 is simply : template<class _Ty> inline _Ty * addressof(_Ty& _Val) { // return address of _Val return ((_Ty *) &(char&)_Val); } Thank you, MAT.

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Compile error using boost 1.53.0, clang, libstdc++ and C++11
by Roman Himmes 11 May '13

11 May '13

Hi, at the moment I try to compile a project that is using boost on my mac. The project is using c++11 features so I need to use clang with libstdc++. I compiled boost with: |./b2 toolset=clang cxxflags="-stdlib=libc++" linkflags="-stdlib=libc++" | It seems that trying to include "boost/date_time/gregorian/gregorian.hpp" leads to the compile error below. Googling I found some remarks about char16_t and char32_t types new in C++-11. Is that compiler/library combination in boost not supported yet? Has anyone successfully got that combination to work? Best Regards, Roman Himmes In file included from basic_log_setup.cpp:1: In file included from ./basic_log_setup.hpp:6: In file included from ../../../cryptotec/cryptotec/base/basic_types.hpp:5: In file included from /Users/username/Development/3rdParty/boost_1_53_0/boost/date_time/gregorian/gregorian.hpp:20: In file included from /Users/username/Development/3rdParty/boost_1_53_0/boost/date_time/gregorian/gregorian_types.hpp:25: In file included from /Users/username/Development/3rdParty/boost_1_53_0/boost/date_time/date_generators.hpp:17: In file included from /usr/bin/../lib/c++/v1/sstream:175: /usr/bin/../lib/c++/v1/istream:278:26: error: implicit instantiation of undefined template 'std::__1::ctype<unsigned int>' if (!__ct.is(__ct.space, *__i)) ^ /usr/bin/../lib/c++/v1/istream:1593:57: note: in instantiation of member function 'std::__1::basic_istream<unsigned int, std::__1::char_traits<unsigned int> >::sentry::sentry' requested here typename basic_istream<_CharT, _Traits>::sentry __sen(__is, true); ^ basic_log_setup.cpp:107:2: note: in instantiation of function template specialization 'std::__1::getline<unsigned int, std::__1::char_traits<unsigned int>, std::__1::allocator<unsigned int> >' requested here std::getline(in, out1.codepoints(), separator); ^ /usr/bin/../lib/c++/v1/__locale:388:47: note: template is declared here template <class _CharT> class _LIBCPP_VISIBLE ctype; ^ /usr/bin/../lib/c++/v1/__locale:171:54: error: implicit instantiation of undefined template 'std::__1::ctype<unsigned int>' return static_cast<const _Facet&>(*__l.use_facet(_Facet::id)); ^ /usr/bin/../lib/c++/v1/istream:274:41: note: in instantiation of function template specialization 'std::__1::use_facet<std::__1::ctype<unsigned int> >' requested here const ctype<_CharT>& __ct = use_facet<ctype<_CharT> >(__is.getloc()); ^ /usr/bin/../lib/c++/v1/istream:1593:57: note: in instantiation of member function 'std::__1::basic_istream<unsigned int, std::__1::char_traits<unsigned int> >::sentry::sentry' requested here typename basic_istream<_CharT, _Traits>::sentry __sen(__is, true); ^ basic_log_setup.cpp:107:2: note: in instantiation of function template specialization 'std::__1::getline<unsigned int, std::__1::char_traits<unsigned int>, std::__1::allocator<unsigned int> >' requested here std::getline(in, out1.codepoints(), separator); ^ /usr/bin/../lib/c++/v1/__locale:388:47: note: template is declared here template <class _CharT> class _LIBCPP_VISIBLE ctype; ^ In file included from basic_log_setup.cpp:1:

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Problems with MPI and PBGL
by siva teja 11 May '13

11 May '13

> > > Hi friends, > > I am working on delta stepping algorithm. Recently I came across > "Parallel Boost Library" but when I tried to call distributed > delta-stepping, from /libs/graph_parallel/test as, "mpiCC > -I/usr/lib/openmpi/include/ distributed_shortest_paths_test.cpp ", it is > reporting, > > distributed_shortest_paths_test.cpp:(.text+0x5892): undefined reference to > `boost::mpi::communicator::communicator()' > distributed_shortest_paths_test.cpp:(.text+0x58a8): undefined reference to > `boost::graph::distributed::mpi_process_group::mpi_process_group(boost::mpi::communicator)' > distributed_shortest_paths_test.cpp:(.text+0x5a00): undefined reference to > `boost::graph::distributed::mpi_process_group::~mpi_process_group()' > distributed_shortest_paths_test.cpp:(.text+0x5a17): undefined reference to > `boost::graph::distributed::mpi_process_group::~mpi_process_group()' > /tmp/ccP7trmD.o: In function `test_main(int, char**)': > distributed_shortest_paths_test.cpp:(.text+0x5ca7): undefined reference to > `boost::mpi::environment::environment(int&, char**&, bool)' > distributed_shortest_paths_test.cpp:(.text+0x5d60): undefined reference to > `boost::mpi::environment::~environment()' > distributed_shortest_paths_test.cpp:(.text+0x5d7c): undefined reference to > `boost::mpi::environment::~environment()' > /tmp/ccP7trmD.o: In function > `__static_initialization_and_destruction_0(int, int)': > distributed_shortest_paths_test.cpp:(.text+0x5e84): undefined reference to > `boost::system::generic_category()' > distributed_shortest_paths_test.cpp:(.text+0x5e90): undefined reference to > `boost::system::generic_category()' > distributed_shortest_paths_test.cpp:(.text+0x5e9c): undefined reference to > `boost::system::system_category() > ... > ... > .. > .. > > I am not able to compile any of the parallel graph examples. I tested MPI > with some mpi examples from boost website<http://www.boost.org/doc/libs/1_43_0/doc/html/mpi/getting_started.html#mpi.…>and they worked fine. I guess the problem is with linking MPI. I would be > grateful if you could help me out of this situation. > > > > Thanking you, > Siva teja. > > > >

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Re: [Boost-users] Boost-users Digest, Vol 3442, Issue 1
by Dan Searles 11 May '13

11 May '13

>>> Hello, >>> >>> the code here doesn't compile: >>> >>> #include <boost/mpl/string.hpp> >>> #include <iostream> >>> >>> namespace mpl = boost::mpl; >>> >>> typedef mpl::string<'h','e','l','l','o',' ','w','o','r','l','d'>::type >>> my_hello; >>> >>> int main() >>> { >>> std::cout << mpl::c_str<my_hello>::value << '\n'; >>> std::cout << BOOST_MPL_LIMIT_STRING_SIZE << '\n'; >>> } >>> >>> As usual, the example from docs works. The error is: ><snip> >> >> I'm surprised multi-character character constants are being used at all in Boost, they >> are not supposed to be portable: >> >> http://stackoverflow.com/questions/6944730/multiple-characters-in-a-charact… > >Boost has never shied away from non-portable constructs. However, it >*does* wrap non-portable constructs in config macros to ensure a >consistent cross-platform experience, which is what mpl::string does >with multichar literals. Does the wrapping include handling 'qwer' on platforms where int is not 4 bytes? It may, I don't have a way to test it. > >> If you only want to use single character constants, you could place the following #define before any includes: >> > >#define BOOST_MPL_LIMIT_STRING_SIZE (32*4) >> >> That would allow up to 32, provided your compiler supports it (yet another portability issue).>> > >That would increase the compile time and decrease readability for no >benefit, IMO. Opinions may differ on the readability of: typedef mpl::string<'hell','o wo','rld'> ...... vs: typedef mpl::string<'h','e','l','l','o',' ','w','o','r','l','d'>..... But increasing compile time would be bad. That's why I'm asking if it would be possible for there to be an mpl::string<> that takes BOOST_MPL_LIMIT_STRING_SIZE 'char's? [It looks like 'x' started being a char in C++11, so it may be complicated supporting prior versions] > >> Since in C++, the type of 'x' is char, it should be possible to create another overload of >> mpl::string<> that takes BOOST_MPL_LIMIT_STRING_SIZE 'char's, which would work >> the way most people would expect.. > >How do you think most people expect it to work? My opinion is that most programmers would expect BOOST_MPL_LIMIT_STRING_SIZE single character constants to work. I know that multi-character constants are not always portable, so I try not to use them, even if a particular instance may be portable. > >-- >Eric Niebler >Boost.org >http://www.boost.org Dan Searles

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Re: [Boost-users] mpl::c_str<mpl::string<>> compile error
by Dan Searles 11 May '13

11 May '13

>Hello, > >the code here doesn't compile: > >#include <boost/mpl/string.hpp> >#include <iostream> > >namespace mpl = boost::mpl; > >typedef mpl::string<'h','e','l','l','o',' ','w','o','r','l','d'>::type >my_hello; > >int main() >{ > std::cout << mpl::c_str<my_hello>::value << '\n'; > std::cout << BOOST_MPL_LIMIT_STRING_SIZE << '\n'; >} > >As usual, the example from docs works. The error is: > >$ LANG=en g++ t.cpp -o t && ./t >t.cpp:6:64: error: wrong number of template arguments (11, should be 8) >/usr/local/include/boost/mpl/string.hpp:102:12: error: provided for >'template<int C0, int C1, int C2, int C3, int C4, int C5, int C6, int >C7> struct boost::mpl::string' >t.cpp:6:72: error: expected initializer before 'my_hello' >t.cpp: In function 'int main()': >t.cpp:10:26: error: 'my_hello' was not declared in this scope >t.cpp:10:34: error: template argument 1 is invalid > >why does it complain about wrong number of template arguments? >BOOST_MPL_LIMIT_STRING_SIZE is 32? > >$ svn info >... >Path: . >URL: http://svn.boost.org/svn/boost/trunk >Repository Root: http://svn.boost.org/svn/boost >Repository UUID: b8fc166d-592f-0410-95f2-cb63ce0dd405 >Revision: 83988 >... >$ LANG=en g++ --version >g++ (GCC) 4.6.3 20120306 (Red Hat 4.6.3-2) >... > >Thanks, >Olaf I'm surprised multi-character character constants are being used at all in Boost, they are not supposed to be portable: http://stackoverflow.com/questions/6944730/multiple-characters-in-a-charact… If you only want to use single character constants, you could place the following #define before any includes: #define BOOST_MPL_LIMIT_STRING_SIZE (32*4) That would allow up to 32, provided your compiler supports it (yet another portability issue). Since in C++, the type of 'x' is char, it should be possible to create another overload of mpl::string<> that takes BOOST_MPL_LIMIT_STRING_SIZE 'char's, which would work the way most people would expect. Dan Searles

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boost::disable_interruption problem
by Mohammad Daei 10 May '13

10 May '13

Hi. I'm trying to use boost package in Eclipse platform. In this line of code: boost::this_thread::disable_interruption di; Although boost-1.41.0-17 is installed and I have included boost/thread.hpp in the code, I receive the this error: undefined reference to 'boost::this_thread::disable_interruption::disable_interruption() I'm using CentOS 6 and gcc compiler. Anyone knows what's causing this problem?

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Boost Serialization now results in a compiler error - I have a fix, but I'm still unsure as to the cause
by Lasse Laursen 10 May '13

10 May '13

Dear boosters, I work with Cinder, creating an audio mixing app. Having recently reached a milestone, I've upgraded from Vs2010 to Vs2012 as well as to the latest Cinder (0.8.5) which also upgraded boost to 1.53. While porting some code over that uses Serialization, I suddenly provoked the following compiler error: error C4308: negative integral constant converted to unsigned type pointing me at the following code in in the boost print.hpp: template <class T> struct print : mpl::identity<T> #if defined(__MWERKS__) , aux::print_base #endif { #if defined(BOOST_MSVC) enum { n = sizeof(T) + -1 }; #elif defined(__MWERKS__) void f(int); #else enum { n = # if defined(__EDG_VERSION__) aux::dependent_unsigned<T>::value > -1 # else sizeof(T) > -1 # endif }; #endif }; It's specifically the 'enum { n = sizeof(T) + -1 };' which triggers the error. I simplified my code, and it seems to occur regardless of what I do when I use the << operator to serialize the simple object I'm working with. Googling the issue turned up someone else in the same boat who received the same message as a warning, rather than a distinct *error*. The advice given was among other things to issue the following macro: (http://lists.boost.org/boost-users/2010/05/59103.php) BOOST_CLASS_TRACKING(mySimpleObject, boost::serialization::track_never) My question is simply if someone else has experienced something similar after upgrading to vs2012 or perhaps knows what is causing it? Given that I've not touched my code, and it seems to me that simply upgrading provoked this issue, I'm leaning towards assuming it's a recent computability issue between boost and msvc? Regards, Gazoo

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