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[bind, tuple] Custom comparison of tuple elements
by Mark Ruzon 12 Jan '07

12 Jan '07

Assume we have a range of objects of type tuple<T1,T2> and a function object that compares two objects of type T1. How would a person sort this range using this function object and bind? I want something along the lines of: std::sort(first, last, boost::bind<bool>(comp, boost::bind(boost::get<0>, _1), boost::bind(boost::get<0>, _2))); but this isn't remotely close to compiling. I could create a custom function object, but I'd rather learn how to use bind properly. Thanks, Mark

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Re: [Boost-users] portland group compilers (pg++, pgi, pgCC)
by Sohail Somani 11 Jan '07

11 Jan '07

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Server Levent Yilmaz > But with building libraries such as serialization and filesystem, I am > stuck. I have a very limited knowledge of bjam or any other large > scale build system for that matter. Hi, you might try the boost-build mailing list for better results. Good luck! Sohail

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optional_shared_ptr or shared_lazy_ptr extension
by Ovanes Markarian 11 Jan '07

11 Jan '07

Hello all, after some time spent for evaluating the possible scenarios I came up with the following idea. Design of a type wrapper similar to functionality offered by boost:shared_ptr and boost:optional. Let me try to explain the requirements: 1. The new type must model pointer semantics to wrapped type. 2. It must be refernece countable and multi-thread safe in regards of shared operations (copy etc.) as it is the case with shared_ptr 3. It should be able to create the wrapped type on first non-const member access request, which assumes a multi-thread safe operation (when shared accross multiple threads) 4. It should support InPlace factory and custom deleter types 5. It should not pre-allocate the storage for the contained type 6. It should be possible to use static_pointer_cast, dynamic_pointer_cast and const_pointer_cast operations with the new type. Why is optional not an option for me: 1. It preallocates memory, which I would like to save and allocate at first request only 2. The type should not implement deep copy semantics for the contained value type if copied, but act much like a shared_ptr (shallow copy) The most important use case: class A; Main Thread lazy_ptr<A> ptr; Thread 1 | Thread 2 | Thread 3 ------------+--------------------+------------- copy of ptr | copy of ptr | copy of ptr (use_count == 4, get()const returns NULL) | ptr.get()non-const | (use_count == 4, get()non-c will return valid A*) use(*ptr) | | use(*ptr) (using the same instance as created from Thread 2) If dealing intensively with big size data structures this approach can save a lot of memory if none of the threads needs an instance. All comments are highly appreciated. I also posted some comments on the similar issue, but got a suggestion to use boost::optional. Since I was not aware of all the requirements at that time I could not go ahead with a discussion. With Kind Regards, Ovanes Markarian

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[regex] difficulties with the "Leftmost Longest" Rule
by Detlef Meyer-Eltz 11 Jan '07

11 Jan '07

I have a difficulty to predict, which part of a regular expression will match. Example: I have a regular expression for a general HTML tag: <[^>]*> combined with an expression for the body tag: <body([^>]*)> to: (<[^>]*>)|(<body([^>]*)>) This expression matches the text: <body bgcolor="white"> As both alternatives can match the input with the same length, I expected, that the repeated fouth part of the "Leftmost Longest" Rule would determine, which alternatve is chosen: 4. Find the match which has matched the first sub-expression in the leftmost position, along with any ties. If there is only on(e) such match possible then return it. // note the missing 'e' As the tag-expression has no sub-expression at all, the body-expression should win. Its sub-expression could match, but doesn't. It seems to me, that the sequence of the alternatives determines the match. Now I guess, that I misinterpreted 4.: its not a means to predict the matching alternative but only to find the one that matched accidentally? My software constructs lexers from elementary expressions automatically. So it's important for me to direct and predict the expected matching alternative. Are there any other rules? Does the sequence of the alternatives determine the match unmistakably? With Kind Regards, Detlef Meyer-Eltz

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[Threads]
by Manuel Jung 11 Jan '07

11 Jan '07

Hi, I have a strange problem. The destructor of a class calls join_all(). But it seems that he hangs there. Even though some other code behind the join_all() is executed before it finishs! Lets get concret: seal::~seal() { ThgPrgs.join_all(); cout<<"Crabd quits, goodbye"<<endl; } When i run my program, the last message is "Crabd quits, goodbye" and it should exit then, but it doesnt. If i stop it running in gdb an do a backtrace i get the following: #0 0xffffe410 in __kernel_vsyscall () #1 0xb7c796c8 in pthread_join () from /lib/tls/i686/cmov/libpthread.so.0 #2 0xb7d21e6a in boost::thread::join () from /usr/local/lib/libboost_thread-gcc-mt-1_33_1.so.1.33.1 #3 0xb7d224ee in boost::thread_group::join_all () from /usr/local/lib/libboost_thread-gcc-mt-1_33_1.so.1.33.1 #4 0x0808742c in ~seal (this=0x80c9890) at src/seal.cpp:20 #5 0x0808eb55 in checked_delete<seal> (x=0x80c9890) at /usr/local/include/boost/checked_delete.hpp:34 #6 0x0809566a in boost::detail::sp_counted_impl_p<seal>::dispose (this=0x80dc410) at /usr/local/include/boost/detail/sp_counted_impl.hpp:76 #7 0x0805950f in boost::detail::sp_counted_base::release (this=0x80dc410) at /usr/local/include/boost/detail/sp_counted_base_gcc_x86.hpp:145 #8 0x08059555 in ~shared_count (this=0x8103e04) at /usr/local/include/boost/detail/shared_count.hpp:159 #9 0x0808dd1c in ~shared_ptr (this=0x8103e00) at src/seal.h:39 #10 0x08089182 in ~tcp_connection (this=0x8103df8) at src/seal.cpp:212 #11 0x08094273 in checked_delete<tcp_connection> (x=0x8103df8) at /usr/local/include/boost/checked_delete.hpp:34 #12 0x080967d0 in boost::detail::sp_counted_impl_p<tcp_connection>::dispose (this=0x80dcf00) at /usr/local/include/boost/detail/sp_counted_impl.hpp:76 #13 0x0805950f in boost::detail::sp_counted_base::release (this=0x80dcf00) at /usr/local/include/boost/detail/sp_counted_base_gcc_x86.hpp:145 #14 0x08059555 in ~shared_count (this=0x80dc4e8) at /usr/local/include/boost/detail/shared_count.hpp:159 #15 0x0808ddc6 in ~shared_ptr (this=0x80dc4e4) at src/seal.h:66 #16 0x0808e69f in ~value (this=0x80dc4e4) at src/seal.cpp:232 #17 0x0808e700 in ~list3 (this=0x80dc4e0) at src/seal.cpp:232 #18 0x0808e766 in ~bind_t (this=0x80dc4d8) at src/seal.cpp:232 #19 0x080910a7 in ~accept_handler (this=0x80dc4c0) at /usr/local/include/boost/asio/detail/reactive_socket_service.hpp:1228 ---Type <return> to continue, or q <return> to quit--- #20 0x08095595 in ~op (this=0x80dc4b0) at /usr/local/include/boost/asio/detail/reactor_op_queue.hpp:355 #21 0x080918db in boost::asio::detail::reactor_op_queue<int>::op<boost::asio::detail::reactive_socket_service<boost::asio::ip::tcp, boost::asio::detail::epoll_reactor<false> >::accept_handler<boost::asio::basic_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >, boost::_bi::bind_t<void, boost::_mfi::mf2<void, tcp_server, boost::shared_ptr<tcp_connection>, boost::asio::error const&>, boost::_bi::list3<boost::_bi::value<tcp_server*>, boost::_bi::value<boost::shared_ptr<tcp_connection> >, boost::arg<1> > > > >::destroy_handler (base=0x80dc4b0) at /usr/local/include/boost/asio/detail/reactor_op_queue.hpp:355 #22 0x080709d2 in boost::asio::detail::reactor_op_queue<int>::op_base::destroy (this=0x80dc4b0) at /usr/local/include/boost/asio/detail/reactor_op_queue.hpp:294 #23 0x0806df75 in boost::asio::detail::reactor_op_queue<int>::destroy_operations (this=0x80c99a8) at /usr/local/include/boost/asio/detail/reactor_op_queue.hpp:245 #24 0x0806d677 in boost::asio::detail::epoll_reactor<false>::shutdown_service (this=0x80c9970) at /usr/local/include/boost/asio/detail/epoll_reactor.hpp:108 #25 0x0806c2ec in ~service_registry (this=0x80c98d8) at /usr/local/include/boost/asio/detail/service_registry.hpp:53 #26 0x0806ba81 in ~io_service (this=0x80c98d4) at src/seal.cpp:8 #27 0x08087648 in ~seal (this=0x80c9890) at src/seal.cpp:32 #28 0x0808eb55 in checked_delete<seal> (x=0x80c9890) at /usr/local/include/boost/checked_delete.hpp:34 #29 0x0809566a in boost::detail::sp_counted_impl_p<seal>::dispose (this=0x80da710) at /usr/local/include/boost/detail/sp_counted_impl.hpp:76 #30 0x0805950f in boost::detail::sp_counted_base::release (this=0x80da710) at /usr/local/include/boost/detail/sp_counted_base_gcc_x86.hpp:145 #31 0x08059555 in ~shared_count (this=0xbfa2e124) at /usr/local/include/boost/detail/shared_count.hpp:159 #32 0x0808dd1c in ~shared_ptr (this=0xbfa2e120) at src/seal.h:39 #33 0x080a8d68 in boost::shared_ptr<seal>::reset (this=0x80c8824) at /usr/local/include/boost/shared_ptr.hpp:231 #34 0x080a863e in main (argc=1, argv=0xbfa2e204) at src/crabd.cpp:71 The class seal holds some other classes in shared_ptrs which are will be destroyed in this moment too. Some of them have also a join_all() in their destructors. Im wondering if they produce the lock? But the main question here is: I read "Crabd quits, goodbye" and after this i stop the program and i get in the backtrace from gdb the line "#4 0x0808742c in ~seal (this=0x80c9890) at src/seal.cpp:20". And Line 20 in seal.cpp is the line with join_all(). How is this possible, though join_all should block? Thanks for your help and for reading this. Manuel Jung, Germany

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[Statechart] Porting to Embedded Linux and C (not C++)
by Stern, Eli 11 Jan '07

11 Jan '07

For the embedded software project I am working on, we are seeking a library to run Statecharts. The run-time environment is : * ARM cpu * Linux 2.6 * C (not C++) * Embedded / real-time application I read about the Boost.Statechart tool, and have some questions, mostly concerning the run-time part of the tool. 1. Is there anyone out there using the tool on similar environments? a. If you do i. Can you comment on the effort required to port the tool to a Linux (preferably 2.6) environment? ii. Can you supply some measures concerning real-time restrictions caused by using the tool (added latencies, memory usage, determinism, ...) b. Can one of the developers comment on the above (assuming there are no user comments)? 1. One of my greatest concern is the fact we are working in C. This introduces several problems a. Mixing C and C++. This is my smallest concern, since the compilers should have solved this long ago. b. Connecting the C++ produced by the tool to our C code. c. We do not have personnel proficient in C++. This means that the above problems, together with any deeper understanding of the internals of the tool will be problematic. This will hurt mostly during debug and integration. 2. Is there a visual tool to draw statecharts that generates Boost.Statechart code? 3. I did not find the tool on boost.org. Does this mean it has not been formally released? I would appreciate any comment on any of the above subjects. Thanx Eli Stern

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[Statechart] Request for user experience/opinion
by Stern, Eli 10 Jan '07

10 Jan '07

As [Statechart] seems not to be in the official Boost distribution, I would like to get some users' opinions of the quality and stability of this tool. Thanx Eli Stern

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Re: [Boost-users] [boost.mpl] Implementing a numeric index access to fields of a composite class created with mpl::inherit_linearly
by Ovanes Markarian 10 Jan '07

10 Jan '07

Hi! you could use an mpl::pair type to produce a static mapping of int value to type: mpl::pair<mpl::int_<0>, int> This is a little bit ugly, to write such a big construct, so you can write the following construct template<int N, class T> struct pair_c : mpl::pair<mpl::int_<N>, T> {}; Actually pair_c could be your DataField struct, so you can add the T instance to it: template<int N, class T> struct pair_c : mpl::pair<mpl::int_<N>, T> { T dataField; }; Now you can define a vector of pair types as follows: mpl::vector<pair_c<0, int>, pair_c<1, int>, pair_c<2, int> > my_vector; we use in this sample pair_c to make any type unique, dependent on the position in the vector. The next step would be to define the class with linear inheritance: template<class Seq> struct linear_inherited : boost::mpl::inherit_linearly < Seq , boost::mpl::inherit<boost::mpl::_1, boost::mpl::_2> >::type {}; But now you would need the access function. I suggest to integrate this function as a linear_inherited member: template<class Seq> struct linear_inherited : boost::mpl::inherit_linearly < Seq , boost::mpl::inherit<boost::mpl::_1, boost::mpl::_2> >::type { template<long N> typename boost::mpl::at_c<Seq, N>::type::second& nth_field() { typedef typename boost::mpl::at_c<Seq, N>::type* ptr_type; ptr_type ptr = static_cast<ptr_type>(this); return ptr->dataField; } }; When this function is a member you save some effor on passing the sequence type to its specialization, otherwise it will not know which type is meant. Let me explain this function: mpl has the at metafunction, which can access the Nth element of a static vector. Here this function is used to calculate the result_type (in our case it is always int, but we want to be generic ;), so you can make pair_c<0, double>, pair_c<1, SomeStruct> etc.). The at metafunction returns the type which was in the vector at this position, in our case this type is pair_c. Now we need to access the field type T. mpl::pair is defined as template <class X, class Y> struct pair { typedef X first; typedef Y second; }; so, the type of our datafield in pair_c is of type second. Therefore the function nth_field returns reference to second. In the function itself we use the static_cast operator to calculate the offset to our datafield within the class. And then we return the the field contained there. Below is the full listing I used to test and compile the scenario: linear_inh_test.h ---------- START ------------------- #ifndef __OM_LINEAR_INHERITANCE_TEST_H__ #define __OM_LINEAR_INHERITANCE_TEST_H__ #include <boost/mpl/at.hpp> #include <boost/mpl/int.hpp> #include <boost/mpl/pair.hpp> #include <boost/mpl/lambda.hpp> #include <boost/mpl/inherit.hpp> #include <boost/mpl/identity.hpp> #include <boost/mpl/placeholders.hpp> #include <boost/mpl/inherit_linearly.hpp> template<int N, class T> struct pair_c : boost::mpl::pair<boost::mpl::int_<N>, T> { T dataField; }; template<class Seq> struct linear_inherited : boost::mpl::inherit_linearly < Seq , boost::mpl::inherit<boost::mpl::_1, boost::mpl::_2> >::type { template<long N> typename boost::mpl::at_c<Seq, N>::type::second& nth_field() { typedef typename boost::mpl::at_c<Seq, N>::type* ptr_type; ptr_type ptr = static_cast<ptr_type>(this); return ptr->dataField; } }; #endif __________ END ___________________ main.cpp ---------- START ------------------- #include "linear_inh_test.h" #include <cassert> #include <boost/mpl/vector.hpp> int main() { using namespace boost; typedef mpl::vector<pair_c<0, int>, pair_c<1, int>, pair_c<2, int> > my_vector; linear_inherited<my_vector> test_instance; int& ref0 = test_instance.nth_field<0>(); ref0 = 0; int& ref1 = test_instance.nth_field<1>(); ref1 = 1; int& ref2 = test_instance.nth_field<2>(); ref2 = 2; assert( test_instance.nth_field<0>() != test_instance.nth_field<1>() != test_instance.nth_field<2>() ); return 0; } __________ END ___________________ With Kind Regards, Ovanes Markarian On Tue, January 9, 2007 21:51, Khalil Shalish wrote: > Hello, > > I created the following composite class using mpl::inherit_linearly: > > template <class T> > struct DataField { > T data; > } > > typedef mpl::inherit_linearly< > mpl::vector< int, int, int> > mpl::inherit< DataField<_2>, _1 > >> Int3Composite; > > Int3Composite int3comp; > > Since the type of each data field is an int, I cannot use the type of the field to access the data in the field. > > Q: Is there a way to write a template (call it get_field) to access the data using numeric position in the type sequence. Something like this: > > int field_0 = get_field<0>(in3comp); //This returns the first int data field. int field_1 = get_field<1>(int3comp); > > I am very new to C++ template programming and any help on this will be very much appreciated. > > Thank you, > Khalil Shalish > kshalish(a)austin.rr.com > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users > With Kind Regards, Ovanes

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Deriving Serialization classes
by Miguel Silvestre 10 Jan '07

10 Jan '07

Hi there!!! Now I'm trying to include the boost serialization library on my project through class derivation. I've followed the demo_fast_archive.cpp and the binary serialization is compiling and working fine. Now I'me trying to make the same for the text serialization and then for the xml serialization. But when compiling I'm getting these link errors: Linking... Creating library ..\..\Bin\silvestre.lib and object ..\..\Bin\silvestre.exp main2.obj : error LNK2019: unresolved external symbol "public: __thiscall boost::archive::text_oarchive_impl<class FlowEngine::TextArchiveO>::text_oarchive_impl<class FlowEngine::TextArchiveO>(class std::basic_ostream<char,struct std::char_traits<char> > &,unsigned int)" ( ??0?$text_oarchive_impl@VTextArchiveO@FlowEngine@@@archive@boost@@QAE@AAV?$basic_ostream@DU?$char_traits@D@std@@@std@@I@Z) referenced in function "public: __thiscall FlowEngine::TextArchiveO::TextArchiveO(class std::basic_ostream<char,struct std::char_traits<char> > &,unsigned int)" ( ??0TextArchiveO@FlowEngine@@QAE@AAV?$basic_ostream@DU?$char_traits@D@std@@@std@@I@Z ) main2.obj : error LNK2019: unresolved external symbol "public: __thiscall boost::archive::text_iarchive_impl<class FlowEngine::TextArchiveI>::text_iarchive_impl<class FlowEngine::TextArchiveI>(class std::basic_istream<char,struct std::char_traits<char> > &,unsigned int)" ( ??0?$text_iarchive_impl@VTextArchiveI@FlowEngine@@@archive@boost@@QAE@AAV?$basic_istream@DU?$char_traits@D@std@@@std@@I@Z) referenced in function "public: __thiscall FlowEngine::TextArchiveI::TextArchiveI(class std::basic_istream<char,struct std::char_traits<char> > &,unsigned int)" ( ??0TextArchiveI@FlowEngine@@QAE@AAV?$basic_istream@DU?$char_traits@D@std@@@std@@I@Z ) main2.obj : error LNK2019: unresolved external symbol "public: void __thiscall boost::archive::text_iarchive_impl<class FlowEngine::TextArchiveI>::load_override(struct boost::archive::class_name_type &,int)" ( ?load_override@?$text_iarchive_impl@VTextArchiveI@FlowEngine@@@archive@boost@@QAEXAAUclass_name_type@23@H@Z) referenced in function "protected: void __thiscall FlowEngine::TextArchiveI::load_override<struct boost::archive::class_name_type>(struct boost::archive::class_name_type &,int)" ( ??$load_override@Uclass_name_type@archive@boost@@@TextArchiveI@FlowEngine@@IAEXAAUclass_name_type@archive@boost@@H@Z ) main2.obj : error LNK2019: unresolved external symbol "public: void __thiscall boost::archive::text_oarchive_impl<class FlowEngine::TextArchiveO>::save(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" ( ?save@?$text_oarchive_impl@VTextArchiveO@FlowEngine@@@archive@boost@@QAEXABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) referenced in function "public: static void __cdecl boost::archive::save_access::save_primitive<class FlowEngine::TextArchiveO,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > >(class FlowEngine::TextArchiveO &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" ( ??$save_primitive@VTextArchiveO@FlowEngine@@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@save_access@archive@boost@@SAXAAVTextArchiveO@FlowEngine@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z ) ..\..\Bin\silvestre.exe : fatal error LNK1120: 4 unresolved externals Error executing link.exe (tool returned code: 1120) silvestre - 5 error(s), 0 warning(s) For a better understand of the problem I'm going to attach the source files Note that I've not tested/look XMLSerialization.h, so it must have errors to I guess.. -- Miguel Silvestre

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What happened to my post?
by Ovanes Markarian 10 Jan '07

10 Jan '07

Hi! I posted 1.5 hours ago an answer to this mailing: http://lists.boost.org/boost-users/2007/01/24486.php But it is still not online? My opponent might wish to get an answer. Why does it take so long? Is it the size of my post (about 5K)? With Kind Regards, Ovanes Markarian

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