May 2010 - Boost-users - lists.boost.org

mpl: copy algorithm question
by Hicham Mouline 16 May '10

16 May '10

Hello, I need to copy a range_c into a vector_c because I need to transform that sequence, and I have difficulties transforming range_c . This code works typedef boost::mpl::range_c<std::size_t, 2u, 10> range_t; typedef boost::mpl::vector_c<std::size_t> all_dims1_t; typedef boost::mpl::copy< range_t, boost::mpl::back_inserter<all_dims1_t> >::type all_dims_t; but then I need the 10 to be a template parameter, so I wrap it in this struct template <std::size_t max_dim> struct S { typedef boost::mpl::range_c<std::size_t, 2u, max_dim> range_t; typedef boost::mpl::vector_c<std::size_t> all_dims1_t; typedef boost::mpl::copy< range_t, boost::mpl::back_inserter<all_dims1_t> >::type all_dims_t; }; The error is: error: type 'boost::mpl::copy<...>' is not derived from type 'S<max_dim>' Really strange? Regards,

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multi_array: once more about a number of dimensions known only at runtime
by Hicham Mouline 16 May '10

16 May '10

Hello, I have been directed to this discussion: http://lists.boost.org/boost-users/2009/08/50601.php when I asked this question before. There are interesting solutions from OvermindDL1 and from Jesse Perla. Basically, define a variant over all the possible multi_array types as: template <typename T, std::size_t max_dim > class multi_array_runtime_dims { typedef variant< multi_array<T, 2>, multi_array<T, 3>, ... multi_array<T, max_dim> > type; }; Setting up the extents can be done at runtime as well. I wonder if there has been further thought about the issue, and also what the library designers thinks about it. Regards,

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[thread] windows.h threads and boost.thread can work together?
by martabm 16 May '10

16 May '10

Hi everyone. In an existing and large visual c++ application, I want to port threads from windows.h ones (CreateThread function) to boost.thread. Due to the size of the application I must do it progressively, so it means, during a while, the coexistence of windows threads with boost threads. Is it a bad idea? Can they work together? Threads here are synchronized by events and critical sections which also I want to port to boost Condition Variables and Mutexes. I'm using a visual C++ 2008, with win32. Thank you in advance, Marta.

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boost iostreams zlib_compressor not compatible with zlib.NET
by Johan Ditmar 16 May '10

16 May '10

Hello, I would like to send compressed data between my C# to a C++ application in ZLIB format. In C++, I use the iostreams::zlib_compressor/zlib_decompressor. In C# I am currently using the ZOutputStream available in the zlib.NET library. First of all, when I compress the same data using both libraries, the results look different: 1.boost::iostreams::zlib_compressor: FF 13 49 48 00 00 01 00 01 00 00 00 63 61 60 60 F8 00 C4 C1 25 45 99 79 E9 23 87 04 00 2.zlib.NET (zlib.ZOutputStream): FF 13 49 48 00 00 01 00 01 00 00 00 78 9C 63 61 60 60 F8 00 C4 C1 25 45 99 79 E9 23 87 04 00 4F 31 63 8D (Note the 78 9C pattern that is present in zlib.NET, but not in boost). Furthermore, when I decompress data in zlib_decompressor that I compressed in zlib.NET, I am not able to read from the stream suggesting something is wrong. It does work when I try to decompress data compressed in the zlib_compressor. Does anybody know what is behind this incompatibility and whether there is an easy solution? Thank you, Johan _________________________________________________________________ http://clk.atdmt.com/UKM/go/197222280/direct/01/ We want to hear all your funny, exciting and crazy Hotmail stories. Tell us now

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[Program Options] Linking both statically and dynamically
by Anthony Foglia 16 May '10

16 May '10

We are trying to link boost program options both statically and dynamically in an executable but when the executable finishes, it glibc reports a "double free or corruption" error. The odd linking arises because we have a common library for our project with some modifications to program options (in particular a parser with built-in help and version options), but our executable code still refers to program options directly (both because it needs to use functions and classes from program options, and because the code hasn't been updated to use our custom parser.) We are linking dynamically to the system-wide program options library, but our utility library is built and linked to statically. (Our build system is boost-build, which determines the linker line.) Should such a linking be possible? Our workaround is to force all linking to program options to be static, which I think I've figured out. -- Anthony Foglia Princeton Consultants (609) 987-8787 x233

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[Asio]Question about error_code when socket::close
by Comet 15 May '10

15 May '10

The documentation says, " Any asynchronous send, receive or connect operations will be cancelled immediately, and will complete with the boost::asio::error::operation_aborted error." Is this the only way that boost::asio::error::operation_aborted be passed to async handlers? I want to distinguish the error_code set by calling socket::close from any other ways (like system error, network error, etc), otherwise, I can't determine whether I should delete the object in async handlers, because some have already been deleted after I call socket::close. If boost::asio::error::operation_aborted definitely means "socket::close is called", I can distinguish this situation. I've tried using boost::weak_ptr with boost::bind,but the performance decrease dramatically. thx.

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Class generation using inherit_linearly
by Peter Nyssen 15 May '10

15 May '10

Dear boost users, I'm clearly missing something w.r.t. mpl_inherit and lamba functions. Could someone enlighten me as to why the following code fails to compile? The integer template argument in the lambda expression seems to be the cause? //-------------------------- #include <boost/mpl/inherit.hpp> #include <boost/mpl/inherit_linearly.hpp> #include <boost/mpl/placeholders.hpp> #include <boost/mpl/vector.hpp> using namespace boost; using namespace boost::mpl::placeholders; template <int C, class T> struct Wrap { T value; }; typedef mpl::vector< int, long > myMemberTypes; typedef mpl::inherit_linearly< myMemberTypes, mpl::inherit<_1, Wrap<5, _2> > >::type MyClass; //-------------------------- Many thanks, Peter

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[Spirit] question about alternative list expressions
by philip tucker 15 May '10

15 May '10

/* Hello, This code (second copy attached) compiles to recognize dotlists, ie "a", "a.b", etc. I want to report on incomplete list errors of the following kind a. a.# The parser now detects such errors by failing to parse them completely. Instead I want to expect an id after a '.'. In dotlist_grammar() I wanted to replace this expression start %= (id % '.') ; with this one start %= (id >> (*('.' > id))) ; // XXX but it won't compile. Neither will this start %= (id >> (*('.' >> id))) ; // XXX What's wrong? Is there a difference between the synthesized attributes of the two alternative list expressions? Or is it a different bug? P.S. Both expressions seem to work for int_ instead of id. Thanks. */ #include <boost/config/warning_disable.hpp> #include <boost/spirit/include/qi.hpp> #include <boost/fusion/include/adapt_struct.hpp> #include <boost/spirit/include/phoenix_core.hpp> #include <boost/spirit/include/phoenix_operator.hpp> #include <boost/spirit/include/phoenix_fusion.hpp> #include <boost/spirit/include/phoenix_stl.hpp> #include <boost/spirit/include/phoenix_object.hpp> #include <boost/fusion/include/adapt_struct.hpp> #include <boost/fusion/include/io.hpp> #include <boost/fusion/sequence.hpp> #include <boost/fusion/include/sequence.hpp> #include <boost/algorithm/string/trim.hpp> #include <iostream> namespace ecgp { using namespace std; namespace qi = boost::spirit::qi; namespace ascii = boost::spirit::ascii; namespace fusion = boost::fusion; namespace phoenix = boost::phoenix; typedef ascii::space_type space; // structures, etc. struct structure { vector<string> dotlist; int filler; // fusion requires >1 members?! void print(ostream& o) const { int i=0; BOOST_FOREACH(string s, dotlist) { if(++i > 1) o << '.'; o << s; } } }; ostream& operator<<(ostream& o, structure const & c) { c.print(o); return o; }; } BOOST_FUSION_ADAPT_STRUCT( ecgp::structure, (std::vector<std::string>, dotlist) (int, filler) // fusion requires >1 members?! ) namespace ecgp { // actions void print_str(string const & v) { cout << "str: "; cout << v << endl; } void print_dotlist(vector<string> const & v) { cout << "dotlist: "; int i=0; BOOST_FOREACH(string s, v) { if(++i > 1) cout << '.'; cout << s; } cout << endl; } void print_structure(structure const & v) { cout << "structure: "; print_dotlist(v.dotlist); cout << endl; } // grammars template <typename Iterator> // recognize an identifier struct id_grammar : qi::grammar<Iterator, string(), space> { id_grammar() : id_grammar::base_type(start) { using ascii::alpha; using qi::lexeme; start %= lexeme[ +alpha ] [ &print_str ] ; } qi::rule<Iterator, string(), space> start; }; template <typename Iterator> // recognize a dotlist, ie (string % '.') struct dotlist_grammar : qi::grammar<Iterator, vector<string>(), space> { dotlist_grammar() : dotlist_grammar::base_type(start) { using qi::int_; using qi::lexeme; start %= // (id >> (*('.' > id))) // XXX (id % '.') [ &print_dotlist ] ; } id_grammar<Iterator> id; qi::rule<Iterator, vector<string>(), space> start; }; template <typename Iterator> struct structure_grammar : qi::grammar<Iterator,structure(),space> { structure_grammar() : structure_grammar::base_type(start) { using qi::eps; using qi::int_; start %= ( dotlist >> (int_ | eps) // filler ) [ &print_structure ] ; } dotlist_grammar<Iterator> dotlist; qi::rule<Iterator, structure(), space> start; }; } int main() { using namespace std; using namespace ecgp; using namespace boost; typedef string::const_iterator string_iterator; string s; cout << "enter a dotlist:\n"; while (getline(cin, s)) { trim(s); string_iterator iter = s.begin(); string_iterator end = s.end(); string target(iter, end); structure list_container; structure_grammar<string_iterator> g; bool r = phrase_parse(iter, end, g, boost::spirit::ascii::space, list_container); if (r && iter == end) { cout << "OK: " << target; cout << endl << endl; } else { cout << "FAIL"; if(! r) cout << "(p)"; if(iter != end) cout << "(e)"; cout << ": " << target; cout << endl << endl; } cout << "enter a dotlist:\n"; } return 0; }

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statechart not working...
by Noah Roberts 14 May '10

14 May '10

Why isn't this statechart doing anything? struct mouse_move : sc::event<mouse_move> {}; struct lock_fly : sc::event<lock_fly> {}; struct unlock_fly : sc::event<unlock_fly> {}; struct arrow_outer; struct arrow_tool : sc::state_machine<arrow_tool,arrow_outer> {}; struct unlocked; struct arrow_outer : sc::simple_state<arrow_outer, arrow_tool, unlocked> {}; struct locked : sc::simple_state<locked, arrow_outer> { locked() { std::cerr << "locked\n"; } ~locked() { std::cerr << "unlocking\n"; } typedef sc::transition<unlock_fly, unlocked> reactions; }; struct unlocked : sc::simple_state<unlocked, arrow_outer> { unlocked() { std::cerr << "unlocked\n"; } ~unlocked() { std::cerr << "locking\n"; } typedef sc::transition<lock_fly,locked> reations; }; int main() { arrow_tool tool; tool.initiate(); //tool.process_event(mouse_move()); tool.process_event(lock_fly()); //tool.process_event(mouse_move()); tool.process_event(unlock_fly()); //tool.process_event(mouse_move()); std::cin.get(); } I expect: unlocked locking locked unlocking unlocked locking I get: unlocked locking My events are obviously not triggering transitions. From what I can tell it's almost exactly like the stopwatch example with some different names and no self-transition in the outermost state. I've stepped through the program and it seems that the event processor ends up passing everything down as an unrecognized event. -- http://crazyeddiecpp.blogspot.com/

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[GIL] How do you use GIL?
by Lubomir Bourdev 14 May '10

14 May '10

If you are using GIL in your project and don’t mind being quoted, could you please email me your name, your project/company or university and any optional comments? We will be giving a tutorial for Boost.GIL at the CVPR 2010 conference in San Francisco on June 13. CVPR is an international conference in computer vision attended by many people from both industry and academia. This is an opportunity to promote the boost libraries in general. Thanks, Lubomir

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