January 2012 - Boost-users - lists.preview.boost.org

[BGL] Serialize boost::labeled_graph
by Alper Aydemir 15 Jan '12

15 Jan '12

Hi, Is there anyway to easily serialize labeled_graphs ? I can see that <boost/graph/adj_list_serialize.hpp> does it for adjacency lists, however no such header seem to exist for labeled graph type. -- Alper Aydemir

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Multi Threaded Server with boost asio
by mark pashley 15 Jan '12

15 Jan '12

I am looking at writing a multithreaded tcp server using boost ASIO. I have read through the tutorials and had a look at some of the examples and just want to check that my understanding is correct. The server will accept connections then service requests from multiple clients. My understanding is as follows: 1 The server uses "a single io_service and a thread pool calling io_service::run()" 2 All threads call io_service::run(). 3 The calls to io_service::run() are not within a strand, ergo completion handlers can run simultaneously. 4 When a request arrives one of the threads is chosen, it's read handler will be called 5 Another request may arrive,starting the read handler on a second thread 6 When one of the threads has finished handling the request it calls async_write, from within a strand 7 Another thread also finishes processing its request, it also calls async_write, from within a strand 8 The writes to the io_service are serialised via the strand, ergo they are thread safe. 9 When the write operation completes the thread calls async_read() 10 This call is not protected by a strand and the thread will be used for handling requests Is my understanding correct? -- View this message in context: http://boost.2283326.n4.nabble.com/Multi-Threaded-Server-with-boost-asio-tp… Sent from the Boost - Users mailing list archive at Nabble.com.

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What's the execution sequence of phoenix::lambda function?
by 饭桶 15 Jan '12

15 Jan '12

I'm a newbie for boost phoenix, I wrote a small piece of code but it totally confuses me about the execution sequence, you can check the code ------------------clip----------------- std::vector<int> v; v.push_back(1); ph::for_each(v, ph::lambda[ph::ref(cout)<<"a", ph::ref(cout)<<"b" ])(v); ph::for_each(arg1, ph::lambda[ph::ref(cout)<<"a", ph::for_each(v, ph::lambda[ph::ref(cout)<<"b", ph::ref(cout)<<"c" ]), ph::ref(cout)<<"d" ])(v); ------------------------clap-------------------------- The first output is "ab" but the second output is "dbca". It seams ph::for_each is lazy evaluate , but what is the correct one to make it execute from left to right? thanks -- 半亩薄田一头牛老婆孩子热炕头

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[asio] usb howto
by László Veréb 15 Jan '12

15 Jan '12

Hi All! I would like to use the asio library to communicate through usb with some devices. I looked the documentation, and searched the internet. It was said that it can be done, but I could not find any specific information. I found a code for (old) serial ports, it mentioned the usb, but nothing more. I think the important parts were: boost::asio::serial_port port; port.open(devname); port.set_option(***); where one can set these options boost::asio::serial_port_base::baud_rate, parity, character_size, flow_control, stop_bits Are these option also available for usb ports? For example the data flows (found by be) are not the same. Thanks beforehand for your reply and help. Laci

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Boost interprocess vector, creating multiple vector pointers
by Prasanth Madhavan 15 Jan '12

15 Jan '12

I want to insert a shared vector into a shared map using the following code: managed_shared_memory segment(create_only ,"MySharedMemory" ,65536); typedef allocator<int, managed_shared_memory::segment_manager> vecAllocator;typedef vector<int, vecAllocator> vec;typedef std::pair<int, vec* > ValueType;typedef allocator<ValueType, managed_shared_memory::segment_manager> ShmemAllocator;typedef multimap<int, vec*, std::less<int>, ShmemAllocator> MyMap; ShmemAllocator alloc_inst (segment.get_segment_manager());vecAllocator vectorallocator (segment.get_segment_manager()); MyMap *mymap = segment.construct<MyMap>("MyMap")(std::less<int>(),alloc_inst);vec *myvec = segment.construct<vec>("myvec")(vectorallocator);vec *myvec1 = segment.construct<vec>("myvec1")(vectorallocator); myvec->push_back(10);myvec->push_back(9);myvec->push_back(8);myvec1->push_back(987);myvec1->push_back(123);myvec1->push_back(456); for(int i = 0; i < 6; ++i){ for(int j = 0; j<6; j++) mymap->insert(std::pair<int, vec*>(i, myvec));}for(int i = 0; i < 6; ++i){ for(int j = 0; j<6; j++) mymap->insert(std::pair<int, vec*>(i, myvec1));}the code works.. but what i want to do is construct a vector without a name. that is do something like this vec *myvec = segment.construct<vec>(vectorallocator);vec *myvec1 = segment.construct<vec>(vectorallocator);so that if i put it inside a loop and there is no problem with naming them differently every loop. Is there a way to do so? Or atleast is there an automatic way to name them differently every loop? -- Prasanth Madhavan

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[xpressive] sporadic crashes in multi-threaded code
by Ovanes Markarian 14 Jan '12

14 Jan '12

Hello *, I face some issue with sporadic crashes in xpressive which I think a result of a race condition. The use case is: a function which needs to parse smth create local regex objects: const sregex any_char = _; sregex const& rdelim = parser_->delimiter(); //some dynamic delimiter token const sregex re_prefix = bos >> (s1=-*by_ref(any_char)) >> *(s2=by_ref(rdelim)) >> eos ; calling this function from multiple threads results in a crash with (boost 1.42, gcc 4.3.5 on debian linux). I previously had more crashes, but moved all regex objects to global space as const objects and they seem to be fine now. This is the only place I left with a local regex. In the stack trace it seems like internals of the local object regex are freed via boost weak_ptr with possible double delete attempt. The stack-trace of the created core-dump during the crash can be accessed via: https://docs.google.com/open?id=0BzJl1eEH-CCGODU5N2JhOTAtNWMxMy00OGNhLThhNz… (Did not want to send addional 200k to the mailing list.) Many thanks for help, Ovanes

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boost::interprocess and synchronization
by Juan Ramírez 13 Jan '12

13 Jan '12

Hi, I've been working a lot with interprocess communication, but using plain windows API. Now I'm thinking about changing the implementation to boost::interprocess, but a simple question arises: Does boost::interprocess provide any kind of synchronization? On past projects I used to create a global mutex and an avent (or semaphore) object, the global mutex makes sure that only one process is writing at the same time, and the event indicates that there is new data to read.. Does boost:.interprocess provide those objects under the hood or I have to use my own named mutex and conditions? Thanks a lot :) Saludos! Juan

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Problems using boost::mpl::for_each
by Allan Nielsen 13 Jan '12

13 Jan '12

Hi, I have a function where I think mpl::for_each might be use full, but I can not get it to work: template<typename SYM> BaseGamePlateHash holdClear(const BaseGamePlateHash& h) { struct ClearSymbol { ClearSymbol(BaseGamePlateHash& h) : hash(h) { } template <typename _SYM> void operator()(_SYM) { hash.clear<_SYM>(); } BaseGamePlateHash& hash; }; BaseGamePlateHash new_hash = h; typedef typename boost::mpl::remove< SymbolCounts, SYM>::type ClearSymbols; ClearSymbol clearsymbol(new_hash); clearsymbol(SYM()); // this is working //boost::mpl::for_each< boost::mpl::vector<SYM> >( clearsymbol ); // not compiling, this is just a simple test //boost::mpl::for_each< ClearSymbols >( clearsymbol ); // not compiling, this is what I want to do... return new_hash; } I had the impression that the following two statements would do the same: clearsymbol(SYM()); // this is working should be equal to: boost::mpl::for_each< boost::mpl::vector<SYM> >( clearsymbol ); // not compiling But this does not seems to be the case... This is the compile error I get when enabling: boost::mpl::for_each< boost::mpl::vector<SYM> >( clearsymbol ); test7.cxx:303:13: error: 'holdClear(const BaseGamePlateHash &)::ClearSymbol::operator()(SymbolCntDice)::ClearSymbol::hash' is not a member of class 'ClearSymbol' hash.clear<_SYM>(); ^ /usr/local/include/boost/mpl/for_each.hpp:75:9: note: in instantiation of function template specialization 'holdClear(const BaseGamePlateHash &)::ClearSymbol::operator()<SymbolCntDice>' requested here aux::unwrap(f, 0)(boost::get(x)); ^ /usr/local/include/boost/mpl/for_each.hpp:100:5: note: in instantiation of function template specialization 'boost::mpl::aux::for_each_impl<false>::execute<boost::mpl::v_iter<boost::mpl::vector<SymbolCntDice, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, 0>, boost::mpl::v_iter<boost::mpl::vector<SymbolCntDice, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, 1>, boost::mpl::identity<mpl_::na>, ClearSymbol>' requested here aux::for_each_impl< boost::is_same<first,last>::value > ^ /usr/local/include/boost/mpl/for_each.hpp:111:5: note: in instantiation of function template specialization 'boost::mpl::for_each<boost::mpl::vector<SymbolCntDice, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::mpl::identity<mpl_::na>, ClearSymbol>' requested here for_each<Sequence, identity<> >(f); ^ test7.cxx:313:5: note: in instantiation of function template specialization 'boost::mpl::for_each<boost::mpl::vector<SymbolCntDice, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, ClearSymbol>' requested here boost::mpl::for_each< boost::mpl::vector<SYM> >( clearsymbol ); ^ test7.cxx:437:36: note: in instantiation of function template specialization 'holdClear<SymbolCntDice>' requested here BaseGamePlateHash hh = holdClear<SYM>( h ); ^ test7.cxx:386:13: note: in instantiation of function template specialization 'BaseGamePreCalc::create_hold_actions<SymbolCntDice>' requested here create_hold_actions<SymbolCntDice>(hash_enum.first); ^ 1 error generated. So, what have I done wrong? Best regards Allan W. Nielsen

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Get fields from struct
by Matthijs Möhlmann 13 Jan '12

13 Jan '12

Hello all, I'm currently busy to get things like this working: struct person { std::string name; int age; }; int main(int argc, char **argv) { person p; p.name = "Matthijs" p.age = 1234; std::string key = "name"; // Now try to fetch the value based on the key string. std::cout << p.{key} << std::endl; // does not compile return 0; } Of course above doesn't work for obvious reasons. The closest I get is: struct person { std::string name; int age; }; namespace keys { struct name; struct age; } BOOST_FUSION_ADAPT_ASSOC_STRUCT( person, (std::string, name, keys::name) (int, age, keys::age) ); int main(int argc, char **argv) { person x; x.name = "Matthijs"; x.age = 1234; std::cout << "Name: " << boost::fusion::at_key<keys::name>(x) << std::endl; std::cout << "Age: " << boost::fusion::at_key<keys::age>(x) << std::endl; return 0; } Now my question, is there maybe another way to achieve this? Regards, Matthijs Möhlmann Cacholong

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boost::date_time with BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG on MinGW: segfault on multithreading
by Yana A Kireyonok (aka Iron Bug) 13 Jan '12

13 Jan '12

Hello, everybody. Looks like I found a bug in date_time library when building with MinGW. I've built static boost 1.48.0 libraries under windows (Win7 64) with MinGW 3.20 (32 bit, GCC 4.6.1) with BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG option and threading=multi link=static runtime-link=static address-model=32 In this case, when using threads (-mthreads) simple operations with timings fail. I simply created a thread that slept for some milliseconds ten times next and it fails. I traced a little, it fails inside date_time functions, called from this_thread::sleep() with SIGSEGV, segmentation fault. That happens in ctor of structure simple_time_rep, out of reasons, at first glance. Looks like this structure or maybe standard time functions of MinGW are not reentrant (this is my guess, I did not dig too deep in the causes of segfault). Without flag BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG it's going all right with timings and threads. But when using precise timings and threading it fails. I also tried flags BOOST_HAS_WINTHREADS and _REENTRANT - that does not affect the case. BOOST_THREAD_USE_LIB was defined (to let it work with static libs). Is this a bug or problem of MinGW of certain version? I haven't found anything similar in bugtracker. Sincerely, Yana A. Kireyonok

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const char* in shared memory object
by Sabine B 13 Jan '12

13 Jan '12

Hi all! I'm a newbie with boost and I'm struggling with objects in shared memory. The following struct is given: struct MyType{ int id; const char* name; const char* rep; MyType(){}; MyType(MyType* const& type){ id = type->id; name = type->name; rep = type->rep; }; Objects of MyType should be shared between processes in shared memory. I have no problem to put and extract the objects from shared space. But I'm struggling with the const char* pointers. I know that pointers are not allowed in shared memory, thats why I tried to realize with boost string by doing the following: typedef boost::interprocess::allocator<char,boost::interprocess::managed_shared_memory::segment_manager> CharAllocator; typedef boost::interprocess::basic_string<char, std::char_traits<char>, CharAllocator> MyString; boost::interprocess::managed_shared_memory segment(boost::interprocess::open_only, "MySharedMemory"); CharAllocator charallocator(segment.get_segment_manager()); struct MyType{ int id; MyString name; MyString rep; MyType(){}; MyType(MyType* const& type){ id = type->id; name = type->name; rep = type->rep; }; But this is not working because the segment and charallocator are not recognized in the struct and if I put boost::interprocess::managed_shared_memory segment(boost::interprocess::open_only, "MySharedMemory"); CharAllocator charallocator(segment.get_segment_manager()); In the struct I get compiler errors. Could anybody help me how I can realize const char* in an object that should be shared? Please help me! Thank you very much! Best regards, Sabine

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Boost.Move template-function parameter
by Luke J. West 12 Jan '12

12 Jan '12

Hi. I'm trying to implement a template function that 'moves' it's parameter. Here's a simple moveable class... struct my_class { my_class() {} my_class(BOOST_RV_REF(my_class)) {} my_class& operator=(BOOST_COPY_ASSIGN_REF(my_class) c) {return *this;} BOOST_COPYABLE_AND_MOVABLE(my_class); }; And here is the function... template<typename T > void steal(BOOST_COPY_ASSIGN_REF(T) c) {} so it works fine when I do this... int main() { my_class c; steal<my_class >(c); } but not when I do this... int main() { int c; steal<int >(c); } It's as if 'int' is not a movable type which of course it trivially is. I read that Boost.Container classes are 'move aware' and I assume boost::vector<int > works, so what am I doing wrong - how to write my 'steal' function capable of moving it's argument when it's moveable class, but not breaking for primitives? Thanks, Luke (hopeful newbie!)

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Question regarding boost::program_options
by Ankur Sinha 12 Jan '12

12 Jan '12

Hello, I've just started using boost. I'm making use of the program_options to take arguments for my tool. I've written the following: > mDesc.add_options() > ("help,h", "Print this usage message.") > ... > .... > .. > ("v-level,v",boost::program_options::value<int>(&mVerboseLevel),"Debug level: 1,2,3\n(default: 0)") > ("version",boost::program_options::value<std::string>()->zero_tokens(),"Package information: version etc.") > and then, I have a method, which I call in main(int argc, char **argv): > /* > *-------------------------------------------------------------------------------------- > * Class: Session > * Method: Session :: ParseCommandLine > * Description: Parse the command line > *-------------------------------------------------------------------------------------- > */ > int > Session::ParseCommandLine (int argc, char **argv) > { > boost::program_options::store(boost::program_options::parse_command_line(argc, argv, mDesc), mVariableMap); > /* notify required to save the values into my variables. */ > /* TODO: confirm this behaviour */ > boost::program_options::notify(mVariableMap); > > if (mVariableMap.count("help")) > { > std::cout << mDesc << std::endl; > return -1; > } > return 0; > } /* ----- end of method Session::ParseCommandLine ----- */ > However, when I invoke my tool, I get an exception (which I admit I haven't handled yet): > [ankur@ankur dump]$ ./src/test --version > terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::program_options::validation_error> >' > what(): in option 'version': at least one value required > Aborted (core dumped) > [ankur@ankur dump]$ > I'm referring this document[1] which says that zero_tokens() implies an argument may or may not be provided. Why is the exception coming up saying I need "at least one value"? What am I missing? Another query: is notify() necessary to save the values provided on the command line to the variables I pass in the add_options() from the variable map (to mVerboseLevel for instance)? [1] http://www.boost.org/doc/libs/1_42_0/doc/html/program_options/overview.html -- Thanks, Regards, Ankur: "FranciscoD" http://fedoraproject.org/wiki/User:Ankursinha http://dodoincfedora.wordpress.com/

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[BGL] creating a single vertex for the loop in a graph
by srinivas boppu 12 Jan '12

12 Jan '12

Hello All, I am looking for the following in boost graph. I have a graph in which I am able to find out the loops. Now, I wanted to replace the whole loop with a single vertex in the same Graph. Is that possible ? if it is, can you suggest me how do it. Alternate way could be, I copy the loop and make another graph and add this whole graph as a "vertex" in initial graph. Can I add a "graph" as a vertex to existing graph? Thanks and regards, Srinivas Boppu

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Boost, git or svn?
by Robert Jones 12 Jan '12

12 Jan '12

I'm confused about the current status of the svn -> git transition,if indeed any such transition is occuring. Boost main page still seems refer to the old SVN repository, but vault references are to a git-hub server. Can someone supply a few sentences of explanation. Thx. - Rob.

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[Range] Range adaptors and compatibility with non-adapted iterators
by John M. Dlugosz 12 Jan '12

12 Jan '12

Consider something like this: themap_type::iterator search_for (int val) { return boost::find_if (themap|map_values, my_predicate(val)); } The return from the function chokes because the adapted iterator type cannot be convered back to the original type of iterator in the parent collection. This is more general. If I wasn't just returning through but using the result within the function, how do I test against end to see if find_if was successful? auto it2= boost::find_if (themap|map_values, my_predicate(val)); if (it2 == themap::end()) // same problem! This seems to be a problem with any algorithm that returns an iterator or otherwise makes the iterators used within the algorithm visible outside of it, even if such usage is just as an "end" flag and not really used to locate the element within the original collection for subsequent iteration. Am I missing something? Is there a good reason why the filtered iterator can't give up the inner original iterator? How do you use range adaptors in these situations? —John

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Help needed in creating Regex...
by Subhash Nagre 12 Jan '12

12 Jan '12

Hi everyone, I need a help in creating a regular expression, I need to select only "Sentences" in String using Regex so I wrote the Code .. *boost::regex re( "(\\S.+?[.!?])(?=\\s+|$)" );* This code considers that sentences break at any of these three characters . ! ? but this code considers string "Mr. Obama" as 2 difference sentences (being a dot character in between), where as I want it to be only one sentence. I have a got a string vector of all the words which have to excluded. std::vector<std:string>exceptionVector; exceptionVector.pushback("Mr.") exceptionVector.pushback("Dr.") exceptionVector.pushback("Mrs.") Now in my regex, I want that if any of the words occur from my vector, it should NOT be a seperate sentence. Any idea how can I create this Regular expression Thanks in Advance -Subhash

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asio raw with PF_PACKET and promiscuous mode?
by Chris Cleeland 11 Jan '12

11 Jan '12

Before I reinvent the wheel, has anybody put together an asio encapsulation of Linux' AF_PACKET sockets with SOCK_RAW? Also, I'm trying to wrap my brain around how I might represent the concept of an "endpoint" for a socket like this. Rather than an IPv4/v6 address, one binds to an interface. So, while there is a concept of a resolver, it resolves an interface name to an interface index value. >From a C/system call perspective, I need to do the following to get the ball rolling: 1. s = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL)) 2. sockaddr_ll myinterface = { .sll_family = AF_PACKET, .sll_protocol = htons(ETH_P_ALL), .sll_ifindex = interfaceIndex("eth0") }, then bind(s, &myinterface) 3. packet_mreq promiscuous_cmd = { .mr_ifindex = interfaceIndex("eth0"), .mr_type = PACKET_MR_PROMISC }, then setsockopt(s, PACKET_ADD_MEMBERSHIP, &promiscuous_cmd) I'm pretty sure that for #1, I need a class packet that models the Protocol concept. But where to put the rest is a bit fuzzier. Do I need to create a whole new "resolver" for interface names? I guess I should also note that, at least for the moment, this is just a means to an end, rather than the end itself. So, I don't need to craft the entire thing--I need to get enough working to be able to easily write some code that can capture all network packets on a given interface, e.g., class snooper { public: snooper(std::string interfacename); void start(); void stop(); ... }; so I can just do something like snooper s("eth0"); s.start(); ...capture stuff... s.stop(); (I'm obviously omitting the part where snooper would hook into objects that would receive and process captured packets, but I'd like for that to work similar to how one plumbs up receipt of udp packets.) -- Chris Cleeland

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casting shared pointers to derived classes
by Don Wilde 11 Jan '12

11 Jan '12

Greetings, all - I am updating a neural network package from the DOS days to modern C++ standards. I have a shared_ptr to a vector of shared_ptrs of type Layer. This class has derived classes OutputLayer, MiddleLayer and InputLayer. Each of these has their own method for calculating output updates, so I need to be able to cast. from boost::shared_ptr<Layer> to static_cast<OutputLayer*>(). Unfortunately, VC++ 2010 will not allow me to do so. It won't even allow a reinterpret_cast. I've looked on the Web and I also have Schalling's guide to Boost. Thank you in advance for your guidance. I'm using boost_1_47_0, if that makes a difference. :D

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[Fwd: How to print the structure of vector of boost::variant]
by Baba Prasad 11 Jan '12

11 Jan '12

Dear friends, please see the bellow my code and tell me how to get out this problem please.when I try to print values of variant it's giving the error as: std::ostream& operator<<(std::ostream&, const status_rsp&): worked.cpp:33: error: const struct status_rsp has no member named os worked.cpp:33: error: const class boost::variant<int, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_> has no member named channelid worked.cpp:33: error: expected ) before ; token worked.cpp:34: error: const class boost::variant<int, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost #include<vector> #include<iostream> #include<boost/variant.hpp> typedef int cid; typedef int n_queue; typedef boost::variant<chid> link_st_rs; typedef std::vector<link_st_rs> link_st_rs_list; typedef boost::variant<n_queue> link_de_rs; typedef std::vector<link_de_rs> link_de_rs_list; using namespace std; struct lparam { int value; }; typedef vector<lparam> link1; struct link_s_rsp { link1 ll; link_st_rs_list lsrl; link_de_rs_list ldrl; }; struct status_rsp { link_s_rsp rsp; friend std::ostream& operator<<(std::ostream& os , const status_rsp& sr) { os << "the value is " << sr.rsp.ll.front().value; os << "id" << sr.rsp.lsrl.front().chid; os << "val" << sr.rsp.ldrl.front().n_queue; return os; } }; typedef vector<status_rsp> srl; int main() { linkparam lp; lp.value =90; link_de_rs_list ldrl; lsrl.push_back(4); ldrl.push_back(3); status_rsp sr; sr.rsp.ll.push_back(lp); srl srl1; srl1.push_back(sr); link1::iterator iter2 = srl1.begin()->rsp.ll.begin(); cout << "A vlue is: " << iter2->value; link_st_rs_list::iterator iter3 = srl1.begin()->rsp.lsrl.begin(); cout << " B value " << iter3->chid; link_de_rs_list::iterator iter4 = srl1.begin()->rsp.ldrl.begin(); cout << "C value" < iter4->n_queue; cin.ignore(); return 0; } Best Regards BaBu -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.

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Needs advices on design ( mpl or processor )
by Allan Nielsen 11 Jan '12

11 Jan '12

Hi This is not a specific questions directly related to Boost::mpl, but a request for help if somebody has the time... For the last couple of month I have been trying to learn to use the boost::mpl library. To learn to use the library I decided to use it for creating a "compressed-enum" library. The library should make it possible to store several enums in a single variable (for instance an unsigned int) Here is a simple example to give en idea: // example enums to play with struct TagA { enum Size { size = 4 }; enum Max { max = 3 }; enum E { A0 = 0, A1 = 1, A2 = 2, A3 = 3, }; }; struct TagB { enum Size { size = 4 }; enum Max { max = 3 }; enum E { B0 = 0, B1 = 1, B2 = 2, B3 = 3, }; }; struct TagC { enum Size { size = 4 }; enum Max { max = 3 }; enum E { C0 = 0, C1 = 1, C2 = 2, C3 = 3, }; }; struct First{}; struct Second{}; int main() { // using the compressed enums library typedef unsigned short STORAGE; typedef CompressedEnums< STORAGE, CompressedEnum<STORAGE, 1, TagA>, CompressedEnum<STORAGE, 4, TagB, First>, CompressedEnum<STORAGE, 16, TagB, Second>, CompressedEnumArray<STORAGE, 64, TagC, 5> > ENUMS; assert(sizeof(ENUMS) == 2)); ENUMS enums; enums.set<TagA>(TagA::A2); enums.set<Second>(TagB::B2); enums.set<3, TagC>(TagC::C2); cout << enums.get<TagA>() << " " << enums.get<Second>(TagB::B2) << " " << enums.get<3, TagC>(TagC::C2) << endl; } CompressedEnums contains the storage variable, and inherit from all its template arguments, and make their methods available through tags. CompressedEnum and CompressedEnumArray only contains static methods which can find the enum in the storage variable. Here is a snippet of my implementation: template < typename STORAGE_TYPE, int OFFSET, typename ENUM_CONTAINER, typename TAG = typename ENUM_CONTAINER::E > struct CompressedEnum { typedef TAG ACCESS_TAG; typedef typename ENUM_CONTAINER::E INNER_TYPE; enum Offset { offset = OFFSET }; enum Size { size = ENUM_CONTAINER::size }; static INNER_TYPE get(const STORAGE_TYPE& data) { return (INNER_TYPE)((data / OFFSET) % size); } ----%<----%<----%<----%<----%<----%<----%<----%<-- } template < typename STORAGE_TYPE, typename B00 = Dummy< 0>, typename B01 = Dummy< 1>, typename B02 = Dummy< 2>, typename B03 = Dummy< 3> > struct CompressedEnums : public B00, B01, B02, B03 { typedef boost::mpl::map<boost::mpl::pair<typename B00::ACCESS_TAG, B00>, boost::mpl::pair<typename B01::ACCESS_TAG, B01>, boost::mpl::pair<typename B02::ACCESS_TAG, B02>, boost::mpl::pair<typename B03::ACCESS_TAG, B03> > TYPE_MAP; template<typename TAG> typename boost::mpl::at<TYPE_MAP, TAG>::type::INNER_TYPE get() const { return boost::mpl::at<TYPE_MAP, TAG>::type::get(data); } ----%<----%<----%<----%<----%<----%<----%<----%<-- STORAGE_TYPE data; }; The code works and does what it is suppose to (as far as I know) but I'm not very happy with the interface: typedef CompressedEnums< STORAGE, // 1 because it is the first CompressedEnum<STORAGE, 1, TagA>, // 4 because TagA::size == 4 CompressedEnum<STORAGE, 4, TagB, First>, // 16 because TagA::size * TagB::size == 16 CompressedEnum<STORAGE, 16, TagB, Second>, // 64 because TagA::size * TagB::size * TagB::size == 64 CompressedEnumArray<STORAGE, 64, TagC, 5> > ENUMS; These magic numbers makes it very easy to make bugs when the code is restructured or changed, and it should be possible to calculate them automatic. If the magic numbers are replaced with their expresions the code will still break of the arguemnts are reordered. To accomplice this I have considered two solutions: macro or more templating... Using macroes I imagin the interface could look something like this: typedef CompressedEnums< STORAGE, ENUM_PACK( STORAGE, 1, (CompressedEnum, TagA) (CompressedEnum, TagB, First) (CompressedEnum, TagB, Second) (CompressedEnumArray, TagC, 5) ) > ENUMS; Which then would expand to the code manual entered above. Alternative using template I imagin that CompressedEnums could change CompressedEnum<STORAGE, 0, TagB, Second> -> CompressedEnum<STORAGE, 16, TagB, Second> automatic and then derive from that one automatic. I tried both, but non of my idea worked out very well, which is why I hope that one of you c++ experts could give me some hints. Best regards Allan W. Nielsen

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depth_first_visit
by James Lindsay 10 Jan '12

10 Jan '12

Hello, I've found several questions regarding the depth_first_visit algorithm but I can't find a complete example anywhere. I was wondering if someone could post a complete example of the depth_first_visit algorithm in action, including how you created the color map. Thanks

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[BGL / General] member of struct is a reference - why?
by Max Limper 10 Jan '12

10 Jan '12

Hi everybody, I was just going through the "File Dependency" example for the graph library and found this piece of code which is a very simple cycle detector: struct cycle_detector : public dfs_visitor<> { cycle_detector( bool& has_cycle) : _has_cycle(has_cycle) { } template <class Edge, class Graph> void back_edge(Edge, Graph&) { _has_cycle = true; } protected: bool& _has_cycle; }; It takes a reference and manipulates the externally declared variable hasCyle via that reference. I tried to change hasCylce to a "regular" member variable, and I just want to read it afterwards, like cycle_detector detector(); boost::depth_first_search(graph, boost::visitor(detector)); if (detector.foundCycles) { //do something } I also thought about giving the cycle detector other member variables, like a list of back edges that gets filled. However, I found that none of those variables gets set the right way, starting with the very simple "bool hasCycle" member. I guess there must be a reason why the person that made the example chose to use a reference, and it only works that way... any ideas why? Thanks a lot in advance.

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[C++ Now! 2012] Deadline extension: Call for Submissions, new deadline is January 20th, 2012
by Hartmut Kaiser 10 Jan '12

10 Jan '12

INAUGURAL C++ NOW! CONFERENCE 2012 Aspen CO, USA, May 14-18, 2012, www.cppnow.org CALL FOR SUBMISSIONS We invite you to submit session proposals to the Inaugural C++ Now! Conference: C++Now! 2012 (Aspen CO, USA, May 14 - 18, 2012). Based on the successful traditions of 5 years of BoostCon, which was the main face-to-face event for all things C++ and Boost (www.boost.org) C++Now! 2012 will present leading speakers from the whole C++ community. The conference name is changing to C++ Now! to reflect the current value of the language, the focus on its new state (from the new Standard), and the need to continually look to the future so the language remains useful to the C++ community. The focus of this conference will be the new C++11 language Standard and as usual Boost: what's new in C++, its Standard library, and in the Boost libraries, how to write and maintain them, how to evangelize or to deploy Boost within your organization. The new C++ Standard, but also the infrastructure and process of Boost, its vision and mission - no matter what you are interested in, it all comes together in the C++Now! sessions. Meet the colleagues, and feel the inspiration to support your work with C++ and Boost for the next year. The C++ Now! Conference is dedicated to discussion and education about C++, an open and free language and standard. Our Conference will focus on discussion and education about open source software usage and developments in the C++ developer and user community. To reflect the breadth of the C++ and Boost communities, the conference includes sessions aimed at three constituencies: C++ and Boost end-users, hard-core Boost library and tool developers, and researchers pushing the boundaries of computation. The program fosters interaction and engagement within and across those groups, with an emphasis on hands-on, participatory sessions. As a multi-paradigm language, C++ is a melting pot where the most compelling ideas from other programming communities are blended in powerful ways. Historically, some of the most popular sessions at C++Now! have highlighted these concepts, from DSLs to functional programming to transactional memory and more. Bring your C#, Python, Ruby or Haskell influences to bear in an environment that will broaden their exposure. IMPORTANT DATES New proposal submissions due: January 20th, 2012. UPDATED! Proposals decisions sent (tentative program): February 17th, 2012. Fully scheduled program available: February 25th, 2012. Session materials due: April 15th, 2012. BEST PRESENTATION AWARDS We know how much effort it takes to prepare talks for our conference. For this reason we will award the best presentations in the following categories: Best Presentation, Best Short Presentation, Best Tutorial, and Best Workshop. The awards will be given based on the audience's voting. Each award will include the author's name listed on the cover of the C++Now! website for that year and a plaque containing all the C++Now! conference information. SESSION TOPICS Topics of interest include, but are not restricted to, the following: * C++11 and how it changes life for users and library writers * General tutorial sessions on C++11, the C++11 Standardslibrary, and one or more Boost libraries * In-depth sessions on using specific Boost libraries * Case studies on using Boost * Experts panels * Advanced sessions on implementation techniques used within Boost libraries * Development workshops to extend or enhance existing Boost libraries * Workshops on design process * Infrastructure workshops such as Build tools, Website, Testing * Concepts and Generic Programming * Hardware and infrastructure presentations focused on how libraries can make better use of the technology * Software development tools and their application to C++ and or Boost * Other topics likely to be of great interest to Boost users and developers Interactive and collaborative sessions are encouraged, as this is the style of learning and participation that has proven most successful at such events. Sessions can be tutorial based, with an emphasis on interaction and participant involvement, or workshop based, whether hands-on programming or paper-based, discussion-driven collaborative work. SESSION FORMATS Presentations Presentations focus on a practitioner's ideas and experience with anything relevant to C++11, Boost and users. Panels Panels feature three or four people presenting their ideas and experiences relating to C++11 and Boost's relevant, controversial, emerging, or unresolved issues. Panels may be conducted in several ways, such as comparative, analytic, or historic. Tutorials Tutorials are sessions at which instructors teach conference participants specific skills relevant to C++11 and Boost. Workshops Workshops provide an active arena for advancements In Boost-relevant topics. Workshops provide the opportunity for experienced practitioners to develop new ideas about a topic of common interest and experience. Author's Corner These were introduced at BoostCon 2008, and were a great Presentations success They are short (30 minute) sessions, focusing on tips on usage and design. In addition, we're looking to uncover the hidden design gems in Boost libraries. Tool Vendors We actively encourage tool vendors and ISP's to submit presentations proposals for a special Tool Vendors Session Track aimed at products related to Boost and C++ (compilers, libraries, tools, etc.). Other formats may also be of interest. Don't hold back a proposal just because it doesn't fit into a pigeonhole. SUBMITTING A PROPOSAL Standard Sessions are 60 minutes. You may submit a proposal for fractions or multiples of 90-minutes. Fractional proposals will be grouped into 60 minute sessions covering related topics. Longer sessions, such as tutorials and classes, will be assigned 90 minute, three hour (i.e. half day), or six hour (i.e. full day) time slots. Please include: * The working title. * Type of session: presentation, panel, tutorial, workshop, authors corner, vendor track, other. * A paragraph or two describing the topic covered, suitable for the conference web site. * Proposed length: 10-20 minute short talks, 45 minutes, 90 minutes, half day, full day. * Alternate lengths, if you are willing to make adjustments: 10- 20 minute short-talks, 45 minutes, 90 minutes, half-day, full day. * Audience: users, developers, both. * Level: basic, intermediate, advanced. * A biography, suitable for the conference web site. * Your contact information (will not be made public). SUBMISSION DETAILS All submissions should be made through the EasyChair conference management system: http://www.easychair.org/conferences/?conf=cppnow2012. If you have not already registered at EasyChair, you will need to do so in order to submit your proposal. All submissions will go through a peer review process. Authors are invited (but are not required) to submit PDF versions of full papers of up to 10 pages in ACM conference proceedings format (see http://www.acm.org/sigs/publications/proceedings-templates) The full papers are not required unless you want them published in the proceedings. All accepted proposals will be made available in the Association for Computing Machinery (ACM) Digital Library (approval pending). Best papers, after further reviews, will be considered to be book chapters or journal articles in a renowned journal. The session materials go on the C++Now! website and will be available to attendees. For general information on the C++Now! 2012 paper submission or the scope of technical papers solicited, please refer to the conference website at www.cppnow.org. For any other questions about the submission process or paper format, please contact the Program Committee at cppnow2012(a)easychair.com. If you have any technical problems with EasyChair, please contact EasyChair for help. Note: Presenters must agree to grant a non-exclusive perpetual license to publish submitted materials, either electronically or in print, in any media related to C++ Now!. Hartmut Kaiser, email: hartmut.kaiser(a)gmail.com (Program Committee Chair) Dave Abrahams, email: dave(a)boostpro.com (Conference Chair) On behalf of the conference organizers

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Quick Unit Test Question
by Brad Tilley 10 Jan '12

10 Jan '12

Hey everyone, I can make BOOST_CHECK produce a failure message like this: BOOST_AUTO_TEST_CASE( test_case2 ) { BOOST_CHECK( 1+1 == 3 ); } But when I try BOOST_WARN, all tests pass: BOOST_AUTO_TEST_CASE( test_case3 ) { BOOST_WARN( 1+1 == 3 ); } Running 3 test cases... *** No errors detected Perhaps I'm doing something wrong. Can someone point me in the right direction? Both BOOST_REQUIRE and BOOST_CHECK work OK. It's only BOOST_WARN that does not work for my testing. Thanks, Brad

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