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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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