August 2009 - Boost-users - lists.boost.org

[Boost.function_types] Function synthesis and property tags
by Yury Korobkin 24 Aug '09

24 Aug '09

Hi, everybody. I'm trying to synthesize a function type G from another function type F with some changes on return and arg types. What I need to leave constant, are all these additional properties that are returned by components<F>::tag. I want them all as a bunch, don't really fancy querying them one by one, they sorta look contradictive or at least redundant. The naive approach of passing the same tag to the function_type<Seq, Tag> does not make a change - it leads to the same result as if default null_tag were passed. How do you generate a function type with the same additional properties as the given one? Sample code: //---------------------------------------------------------------------- ---------------------------- typedef int (__stdcall * pF)(char); typedef int ( * pG)(char); typedef remove_pointer<pF>::type F; typedef components<F> compsF; // generate type hopefully like pF typedef function_pointer<compsF, //create tag from mask and bits detail::property_tag<compsF::bits::value, compsF::mask::value> >::type pfn_gen; BOOST_MPL_ASSERT((is_same<pfn_gen, pG>)); // this one passes, should fail, though BOOST_MPL_ASSERT((is_same<pfn_gen, pF>)); // I wish, but fails //---------------------------------------------------------------------- ---------------------------- Thanks, YuryK This mail was received via Mail-SeCure System. STATEMENT OF CONFIDENTIALITY The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain confidential or privileged information. If you are not the intended recipient, please notify Exent Technologies Ltd. immediately at +972-3-9243828 or by reply e-mail and destroy all copies of this message and any attachments

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functor for boost::thread_group threads: which one is correct?
by Boost lzw 24 Aug '09

24 Aug '09

Hi there, I have two versions (VERSION1 and VERSION2) of a group_helper functor to be called from boost::thread_group, which one of them is correct? class FileThread { public: void print() {...} void find() {...} }; class group_helper { private: boost::shared_ptr<FileThread> m_object; public: //VISION1 group_helper(boost::shared_ptr<FileThread>& object) : m_object(object) { } //VISION2 group_helper() : m_object(boost::shared_ptr<FileThread>(new FileThread)) { } void operator()() { m_object->find(); m_object->print(); } }; On another matter, why the following code results in a runtime exception from the group_helper's dtor? #include <iostream> #include "boost/thread/thread.hpp" class FileThread { public: void find() { } void print() { } }; class group_helper { private: FileThread* m_object; public: group_helper() : m_object(new FileThread) {} void operator()() { m_object->find(); m_object->print(); } ~group_helper() { if (m_object) delete m_object; }// EXCEPTION from dtor }; int main() { group_helper gh; boost::thread thrd(gh); thrd.join(); }

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errors in function_equal.hpp?
by worldeb＠ukr.net 23 Aug '09

23 Aug '09

Hi folks. I use some library which use boost in my project. I am not familiar with c++ and boost. Compilation of my project shows me the next: function_equal.hpp:15: error: expected nested-name-specifier before numeric constant function_equal.hpp:15: error: expected `>' before numeric constant function_equal.hpp:16: error: expected ‘,’ or ‘...’ before numeric constant function_equal.hpp:16: error: ISO C++ forbids declaration of ‘parameter’ with no type function_equal.hpp: In function ‘bool boost::function_equal_impl(const F&, int)’: function_equal.hpp:17: error: ‘g’ was not declared in this scope function_equal.hpp: At global scope: function_equal.hpp:22: error: expected nested-name-specifier before numeric constant function_equal.hpp:22: error: expected `>' before numeric constant function_equal.hpp:23: error: expected ‘,’ or ‘...’ before numeric constant function_equal.hpp:23: error: ISO C++ forbids declaration of ‘parameter’ with no type function_equal.hpp: In function ‘bool boost::function_equal(const F&, int)’: function_equal.hpp:24: error: ‘g’ was not declared in this scope I cannot identify really if it is a problem of the boost, or the libraries which I use or... Who can comment these errors? Thanx a lot.

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Re: [Boost-users] [iostreams] [archive] [serialization] lexical_cast<string> with binary_archive vs. text_archive
by Johann Goetz 23 Aug '09

23 Aug '09

This is not portable across platforms (32/64 for example). I wish to use the portability of ascii when needed. But I want to option to be non-portable (without the stringstream/lexical_cast<string> or gzip) in order to speed up the serialization process. > I don't see what lexical cast is doing in there. > What's the matter with: > numerics -> binary_archive -> gzip -> out_file > Robert Ramey Johann Goetz wrote: > Consider the following serialization archive. I can serialize a > collection of variables (floats, ints, etc) through the series: > numerics --> text_oarchive --> gzip --> output_file > The text_archive step is essentially a stringstream filter. This > filter gives the serialization the portability I (sometimes) need. > > namespace io = boost::iostreams; > namespace ar = boost::archive; > > io::filtering_ostream fos; > fis.push(io::gzip_compressor()); > fis.push(io::file_sink("output.txt.gz")); > ar::text_oarchive oa(fos); > > OK. Now what I wish to do is to create a binary_archive and to push > the stringstream filter to the filtering_ostream: > numerics -> binary_archive -> lexical_cast<string> -> gzip -> out_file > This way I could turn this part (and the gzip) on or off at will (the > ol' speed vs portability thing): > > io::filtering_ostream fos; > fis.push(/*stringstream_filter*/); > fis.push(io::gzip_compressor()); > fis.push(io::file_sink("output.txt.gz")); > ar::binary_oarchive oa(fos); > > I am not sure how to create such a filter, but I'm guessing such a > filter already exists. Perhaps the answer lies in > lexical_cast<string>? any help with this would be greatly > appreciated, thanks! > Johann.

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Invoke several functions with the same thread
by Shaolin 23 Aug '09

23 Aug '09

Hi Guys I am trying to convert my application to a multithreaded app. Please see code below: boost::thread_group threads; FileThread *fThreads[filearr.size()]; for(int i=0; i < filearr.size(); i++) { fThreads[i] = new FileThread(filearr[i]); threads.create_thread(fThreads[i]->find()); } threads.join_all(); As you can see from the code above, I have an array of FileThread objects, which have several functions. What I want to do, is to first off invoke the find() function which will go through some algorthms (this is already done) and then the print() function which will print the results. How can I invoke the print() function with the same thread ?

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[spirit] how to get_position() from a multi_pass<position_iterator <const char*> >
by Peter Schueller 23 Aug '09

23 Aug '09

Hi, I use a position_iterator<const char*> for parsing with boost::spirit. Because I need the regex_p feature, I have to wrap this iterator using a multi_pass iterator. I call pt_parse and get a boost::spirit::tree_parse_info<multi_pass<position_iterator<const char*> >, ...> parse_info. Now I have problems calling the get_position() method on "parse_info.stop". I guess this is the case because multi_pass does not store my iterator but wraps it using boost::iterator which loses the position features of position_iterators and only keeps the const char* pointer. Do you have an advice for me? Thanks and best regards, Peter

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[iostreams] [archive] [serialization] lexical_cast<string> with binary_archive vs. text_archive
by Johann Goetz 23 Aug '09

23 Aug '09

Consider the following serialization archive. I can serialize a collection of variables (floats, ints, etc) through the series: numerics --> text_oarchive --> gzip --> output_file The text_archive step is essentially a stringstream filter. This filter gives the serialization the portability I (sometimes) need. namespace io = boost::iostreams; namespace ar = boost::archive; io::filtering_ostream fos; fis.push(io::gzip_compressor()); fis.push(io::file_sink("output.txt.gz")); ar::text_oarchive oa(fos); OK. Now what I wish to do is to create a binary_archive and to push the stringstream filter to the filtering_ostream: numerics -> binary_archive -> lexical_cast<string> -> gzip -> out_file This way I could turn this part (and the gzip) on or off at will (the ol' speed vs portability thing): io::filtering_ostream fos; fis.push(/*stringstream_filter*/); fis.push(io::gzip_compressor()); fis.push(io::file_sink("output.txt.gz")); ar::binary_oarchive oa(fos); I am not sure how to create such a filter, but I'm guessing such a filter already exists. Perhaps the answer lies in lexical_cast<string>? any help with this would be greatly appreciated, thanks! Johann.

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boost::math function link problem
by joe claire 22 Aug '09

22 Aug '09

Hi all, I am new to boost library. First of all, I apologize that my question will be pretty basic to people in this mailing list, nevertheless I have spent 30 min + to figure it out and couldn't find the answer. So, here it goes... I need to find which library (lib*.a) file contains the "ibeta" function which is defined under boost/math/special_functions/gamma.hpp. When I compile the following simple test.cpp ----------------------------------------- #include <boost/math/special_functions/gamma.hpp> #include <iostream> using namespace std; using namespace boost::math; int main() { cout << "it is my birthday...\n"; cout << ibeta(5, 2, 0.5) << "\n"; } ----------------------------------------- with this command line, g++ -I /my_own_boost_root_path/ test.cpp I get link error message (undefined reference) /tmp/ccgrrT4l.o: In function `main': test.cpp:(.text+0xc1): undefined reference to `boost::math::tools::promote_args<int, int, double, float, float, float>::type boost::math::ibeta<int, int, double>(int, int, double)' collect2: ld returned 1 exit status I know that I just need to put the correct library in the command line, but I can't figure it out. There are 6 lib*.a files in boost_build_dir/bin.vs/libs/math/build/gcc-4.1.2/release/link-static/threading-multi/ I tried to each of them at the end of my compilation command line, in the hope that "ibeta" is contained in one of them, but I failed. 1. Where should I look to find the lib*.a that contains "ibeta" (ibeta is incomplete beta function integral) 2. In general, how do I figure out which lib*.a to use, when I need to use specific classes or functions? (I have looked at "getting started", and "libraries" for proper documentation, but they explain in detail the available libraries, but, not what lib*.a file to use for specific functions...) 3. Is it possible that "ibeta" is not built Thanks a lot !

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boost:thread compiling problem
by Shaolin 22 Aug '09

22 Aug '09

Hi Guys I am try to create a thread with boost but eveytime I execute I get some freaky error messages. See code below followed by error msg: #include <boost/thread/thread.hpp> #include <iostream> using namespace std; void hello() { cout << "hello" << endl; } int main(int argc, char* argv[]) { boost::thread thrd1(&hello); // ERROR caused by the &hello param thrd1.join(); } *Error Message*: /tmp/cc3ymRwv.o: In function `main': main.cc:(.text+0x417): undefined reference to `boost::thread::join()' main.cc:(.text+0x422): undefined reference to `boost::thread::~thread()' main.cc:(.text+0x43b): undefined reference to `boost::thread::~thread()' /tmp/cc3ymRwv.o: In function `boost::mutex::mutex()': main.cc:(.text._ZN5boost5mutexC1Ev[boost::mutex::mutex()]+0x45): undefined reference to `boost::thread_resource_error::thread_resource_error()' main.cc:(.text._ZN5boost5mutexC1Ev[boost::mutex::mutex()]+0x4d): undefined reference to `boost::thread_resource_error::~thread_resource_error()' main.cc:(.text._ZN5boost5mutexC1Ev[boost::mutex::mutex()]+0x55): undefined reference to `typeinfo for boost::thread_resource_error' /tmp/cc3ymRwv.o: In function `boost::detail::thread_data<void (*)()>::~thread_data()': main.cc:(.text._ZN5boost6detail11thread_dataIPFvvEED0Ev[boost::detail::thread_data<void (*)()>::~thread_data()]+0x16): undefined reference to `boost::detail::thread_data_base::~thread_data_base()' /tmp/cc3ymRwv.o: In function `boost::detail::thread_data<void (*)()>::~thread_data()': main.cc:(.text._ZN5boost6detail11thread_dataIPFvvEED1Ev[boost::detail::thread_data<void (*)()>::~thread_data()]+0x16): undefined reference to `boost::detail::thread_data_base::~thread_data_base()' /tmp/cc3ymRwv.o: In function `boost::condition_variable::condition_variable()': main.cc:(.text._ZN5boost18condition_variableC1Ev[boost::condition_variable::condition_variable()]+0x3a): undefined reference to `boost::thread_resource_error::thread_resource_error()' main.cc:(.text._ZN5boost18condition_variableC1Ev[boost::condition_variable::condition_variable()]+0x42): undefined reference to `boost::thread_resource_error::~thread_resource_error()' main.cc:(.text._ZN5boost18condition_variableC1Ev[boost::condition_variable::condition_variable()]+0x4a): undefined reference to `typeinfo for boost::thread_resource_error' /tmp/cc3ymRwv.o: In function `boost::detail::thread_data_base::thread_data_base()': main.cc:(.text._ZN5boost6detail16thread_data_baseC2Ev[boost::detail::thread_data_base::thread_data_base()]+0x1b): undefined reference to `vtable for boost::detail::thread_data_base' /tmp/cc3ymRwv.o: In function `boost::thread::thread<void (*)()>(void (*)(), boost::disable_if<boost::is_convertible<void (*&)(), boost::detail::thread_move_t<void (*)()> >, boost::thread::dummy*>::type)': main.cc:(.text._ZN5boost6threadC1IPFvvEEET_NS_10disable_ifINS_14is_convertibleIRS4_NS_6detail13thread_move_tIS4_EEEEPNS0_5dummyEE4typeE[boost::thread::thread<void (*)()>(void (*)(), boost::disable_if<boost::is_convertible<void (*&)(), boost::detail::thread_move_t<void (*)()> >, boost::thread::dummy*>::type)]+0x32): undefined reference to `boost::thread::start_thread()' /tmp/cc3ymRwv.o:(.rodata._ZTIN5boost6detail11thread_dataIPFvvEEE[typeinfo for boost::detail::thread_data<void (*)()>]+0x8): undefined reference to `typeinfo for boost::detail::thread_data_base' collect2: ld returned 1 exit status

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Unordered map copy segfaults! (STL map does not)
by MeMooMeM 21 Aug '09

21 Aug '09

Hi everyone, When I copy an unordered map, it segfaults. I am not having the same problem with STL's map. Using an unordered map is essential for performance, so I would really appreciate any help! Any ideas? Here are the details: ================ typedef boost::unordered_map<unsigned long long, Dest> MyMap; MyMap a; ... ... // (I populate map 'a' here in a loop) ... MyMap b; b = a; // Segfaults! (also, I do not want to initialize b with a as in MyMap b(a), I want to copy it later in the code.) Where Dest is a struct: struct Dest{ bool exists; int num; int src; int dest; unsigned short pos[64]; Dest () { exists = false; num = 0; src = 0; dest = 0; } ~Dest() { } }; -- View this message in context: http://www.nabble.com/Unordered-map-copy-segfaults%21-%28STL-map-does-not%2… Sent from the Boost - Users mailing list archive at Nabble.com.

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