May 2015 - Boost-users - lists.preview.boost.org

[Interprocess] Can I use google sparsehash?
by Malko 31 May '15

31 May '15

Hi, I thought I would find this question already answered on the internet or in previous posts in the mailing list, but my research is fruitless. Hence, since I am not proficient in the way of allocators, I will ask directly: is it possible to use google sparsehash with Boost.Interprocess? According to the info I found sparsehash can be faster than boost::unordered_map, and I could really use the additional speed. Thanks for the help! -- View this message in context: http://boost.2283326.n4.nabble.com/Interprocess-Can-I-use-google-sparsehash… Sent from the Boost - Users mailing list archive at Nabble.com.

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How to fetch boost libraries and their dependencies from github via CMake
by Gonzalo BG 30 May '15

30 May '15

Dear all, I have a CMake project that requires some header-only boost libraries: - container, dynamic_bitset, math, units I would like CMake to always fetch automatically the latest version of these libraries and their dependencies from github as an external project. AFAIK FindBoost doesn't do this, is there maybe a different cmake script that does? Best regards, Gonzalo

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[MSM] Boost.MSM: statemachine to transition on templatized event-type
by nice sw123 29 May '15

29 May '15

Hi there, having tested Boost.MSM, I'm pretty happy with it. It's interesting, in that it seems to handle all states in a static table. No "new" operator etc. Since there is no "new" and all is static, I cannot use the runtime, to specialize my transitions. So instead, I have to use templates! Unfortunately I'm not a template master, and the compiler is giving me an error. Here's what I'm trying: template <typename EventT> struct Machine_ : public msm::front::state_machine_def<Machine_<EventT> > { // ... struct transition_table : mpl::vector< g_row<StateInitial, EventT, StateEven, &Machine_<EventT>::guardToEven>, g_row<StateInitial, EventT, StateOdd, &Machine_<EventT>::guardToOdd>, g_row<StateInitial, EventT, StateFloat, &Machine_<EventT>::guardToFloat>, g_row<StateEven, EventT, StateEven, &Machine_<EventT>::guardToEven>, g_row<StateEven, EventT, StateOdd, &Machine_<EventT>::guardToOdd>, g_row<StateEven, EventT, StateFloat, &Machine_<EventT>::guardToFloat>, g_row<StateOdd, EventT, StateEven, &Machine_<EventT>::guardToEven>, g_row<StateOdd, EventT, StateOdd, &Machine_<EventT>::guardToOdd>, g_row<StateOdd, EventT, StateFloat, &Machine_<EventT>::guardToFloat>, g_row<StateFloat, EventT, StateEven, &Machine_<EventT>::guardToEven>, g_row<StateFloat, EventT, StateOdd, &Machine_<EventT>::guardToOdd>, g_row<StateFloat, EventT, StateFloat, &Machine_<EventT>::guardToFloat> >{}; // ... } Unfortunately gcc gives this error: d.cpp:119:5: error: ‘g_row’ was not declared in this scope g_row<StateInitial, EventT, StateEven, &Machine_<EventT>::guardToEven>, etc. Can somebody help in this regard? Thanks. nicesw123 In case you're interested. Here's the code of the complete example that I'm trying to get working: #include <iostream> #include <boost/msm/front/state_machine_def.hpp> #include <boost/msm/back/state_machine.hpp> namespace msm = boost::msm; namespace mpl = boost::mpl; // events struct EventNumber1 { // int number! EventNumber1(int num_) : num{num_} {} int getNum() const { return num; } private: int num; }; struct EventNumber2 { // double number! EventNumber2(double num_) : num{num_} {} double getNum() const { return num; } private: double num; }; typedef EventNumber2 MyEvent; // using doubles // StateBase -- a base (parent) state struct StateBase : public msm::front::state<> { StateBase(const std::string& stateName = "") : stateName{stateName} {} template <typename Event, typename FSM> void on_entry(const Event&, FSM&) { std::cout << "Entering " << stateName << std::endl; } template <typename Event, typename FSM> void on_exit(const Event&, FSM&) { std::cout << "Leaving " << stateName << std::endl; } private: std::string stateName; }; #if 0 // not used (just an idea) template <typename T> struct StateMachineFront_Base : public msm::front::state_machine_def<StateMachineFront_Base<T>> { StateMachineFront_Base(const std::string& stateMachineName = "") : stateMachineName{stateMachineName} {} template <typename Event, typename FSM> void on_entry(const Event&, FSM&) { std::cout << "Entering " << stateMachineName << std::endl; } template <typename Event, typename FSM> void on_exit(const Event&, FSM&) { std::cout << "Leaving " << stateMachineName << std::endl; } private: std::string stateMachineName; }; #endif template <typename EventT> struct Machine_ : public msm::front::state_machine_def<Machine_<EventT> > { Machine_(const std::string& stateMachineName = "Machine_") : stateMachineName{stateMachineName} {} template <typename Event, typename FSM> void on_entry(const Event&, FSM&) { std::cout << "Entering " << stateMachineName << std::endl; } template <typename Event, typename FSM> void on_exit(const Event&, FSM&) { std::cout << "Leaving " << stateMachineName << std::endl; } // states struct StateInitial : public StateBase { StateInitial(const std::string name = "StateInitial") : StateBase{name} {} }; struct StateEven : public StateBase { StateEven(const std::string name = "StateEven") : StateBase{name} {} }; struct StateOdd : public StateBase { StateOdd(const std::string name = "StateOdd") : StateBase{name} {} }; struct StateFloat : public StateBase { StateFloat(const std::string name = "StateFloat") : StateBase{name} {} }; // guards bool guardToEven(const EventT& num) { const long long x = static_cast<long long>(num.getNum()); return ((x == num.getNum()) // is Integral type && ((x % 2) == 0)); } bool guardToOdd(const EventT& num) { const long long x = static_cast<long long>(num.getNum()); return ((x == num.getNum()) // is Integral type && ((x % 2) != 0)); } bool guardToFloat(const EventT& num) { const long long x = static_cast<long long>(num.getNum()); return (x != num.getNum()); // is Floating type } typedef StateInitial initial_state; struct transition_table : mpl::vector< g_row<StateInitial, EventT, StateEven, &Machine_<EventT>::guardToEven>, g_row<StateInitial, EventT, StateOdd, &Machine_<EventT>::guardToOdd>, g_row<StateInitial, EventT, StateFloat, &Machine_<EventT>::guardToFloat>, g_row<StateEven, EventT, StateEven, &Machine_<EventT>::guardToEven>, g_row<StateEven, EventT, StateOdd, &Machine_<EventT>::guardToOdd>, g_row<StateEven, EventT, StateFloat, &Machine_<EventT>::guardToFloat>, g_row<StateOdd, EventT, StateEven, &Machine_<EventT>::guardToEven>, g_row<StateOdd, EventT, StateOdd, &Machine_<EventT>::guardToOdd>, g_row<StateOdd, EventT, StateFloat, &Machine_<EventT>::guardToFloat>, g_row<StateFloat, EventT, StateEven, &Machine_<EventT>::guardToEven>, g_row<StateFloat, EventT, StateOdd, &Machine_<EventT>::guardToOdd>, g_row<StateFloat, EventT, StateFloat, &Machine_<EventT>::guardToFloat> >{}; private: std::string stateMachineName; }; typedef msm::back::state_machine<Machine_<MyEvent>> Machine; template <typename T> void postEvents(Machine& machine) { for (T i; std::cin >> i; ) { machine.process_event(MyEvent{i}); } } int main() { Machine machine; machine.start(); postEvents<double>(machine); machine.stop(); return 0; }

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Fwd: [Boost-announce] [boost] [metaparse] Review period starts May 25th and ends June 7th
by Christophe Henry 28 May '15

28 May '15

I had sent this message only to the Developer mailing list. Please let me correct this mistake now. ------------------------------------------------------------------------------------------------------------------------- Dear all, The review of the Metaparse library starts next Monday, May 25th and ends June 7th. Metaparse was written by Abel Sinkovics. Metaparse is a parser generator library for template metaprograms. The purpose of this library is to support the creation of parsers that parse at compile time. This library is intended to be used for embedded domain specific language creation for C++ and can help libraries provide a better interface. It is similar to Boost.Spirit, however while parsers built with Spirit parse at run-time, parsers built with Metaparse parse at compile-time. It makes it possible for library authors to provide an interface that follows the common notation of the problem domain of the library. (eg. SQL queries, grammars, etc written in their common notation instead of similar-looking C++ expressions). For example there is a (yet incomplete) interface for Boost.Spirit that makes it possible to write MPLLIBS_REGEX("^[abcd][3-8]\\.foo$") instead of bos >> set[as_xpr('a')|'b'|'c'|'d'] >> range('3','8') >> '.' >> 'f' >> 'o' >> 'o' >> eos and make the parser built with Metaparse generate the latter expression from the former one. (It can be found here: https://github.com/istvans/mpllibs/tree/master/libs/xlxpressive) Since the library is based on template metaprogramming, the DSLs can be used for type validation as well. This is demonstrated by the type-safe printf implementation ( http://abel.web.elte.hu/mpllibs/safe_printf/index.html) It type-checks the arguments of a printf call based on the format string and has zero runtime overhead compared to unchecked printf. Parsers can be constructed in a declarative manner and (even though this is template metaprogramming based) remain readable. The implementation reflects the grammar it parses (with additional elements for semantic actions). Even though the library requires the parser author to write template metaprograms, the development of parsers is well supported by tools like Metashell and MDB. An important aspect of parsers (built with this library or another one) is error reporting for invalid input. The library offers tools for the parser authors to be able to provide useful error messages in case of parsing errors. Here is an example error report by a parser built with Metaparse (the parser can be found in the Getting Started guide of the library): ..... x__________________PARSING_FAILED__________________x<1, 5, unpaired<1, 1, literal_expected<')'>>> .... It is an error report letting the developer know that a closing paren is missing at line 1, column 5 and the unclosed opening paren is in line 1, column 1. Metaparse can be downloaded from Github: https://github.com/sabel83/mpllibs/tree/master/mpllibs/metaparse And a very complete tutorial: http://abel.web.elte.hu/mpllibs/metaparse/getting_started.html The tutorial also offers the nice feature of a link to metashell for quick-starting trying out the library: http://abel.web.elte.hu/shell/metashell.html Boost.Msm v3 also implements a new compile-time strings based front-end called eUML2 to demonstrate the power of the library and the conciseness and expressiveness it allows. Please have a look at the documentation: https://htmlpreview.github.io/?https://raw.githubusercontent.com/boostorg/m… Everybody on this list is invited to participate in this formal review. I hope to see your review of Metaparse, including your vote on acceptance, and I welcome your participation in the ensuing discussions on the Boost developers' mailing list. Please always include in your review a vote as to whether the library should be accepted into Boost. Additionally please consider giving feedback on the following general topics: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? - With what compiler? - Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? Regards, Christophe Review Manager

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[BGL] Dijkstra shortest paths with custom compare function and zero weight edges
by Christian Ofenböck 27 May '15

27 May '15

I'm using dijkstra_shortest_paths with a custom compare function like (Weight a, Weight b) { return a<=b; } As I've also got some zero weight edges within the graph this leads to problems with the test for negative weights in dijkstra_bfs_visitor's examine_edge-function. The test fails on checking zero weight edges and throws a negative_edge-exception (dijkstra_shortest_paths.hpp:190): if (m_compare(m_combine(m_zero, get(m_weight, e)), m_zero)) evaluates to if(0<=0) Any suggestions on how to solve this issue? For now I just got rid of the test, as I just use unsigned weight values, but of course that's not a sound solution.

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question about filtered_graph
by breadbread1984 25 May '15

25 May '15

I am using boost graph library. In order to get a filtered graph, I adopted filtered_graph. I thought it could be used in the same way as adjacency_list. But when I get target and source from an edge of a filtered graph, I realized the target and source function doesn't accept filtered_graph as its argument. How can I get the two terminals of an edge from a filtered_graph then? Thanks for any hints in advance.

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[Serialization] STL Containers and Non-Default Constructors
by Trevor Thoele 24 May '15

24 May '15

I have recently changed from a hand-rolled serializer to Boost's and while it's mostly been fantastic, there's one problem that I can't seem to shake - I cannot get it to serialize non-default constructible types. It fails on trying to generate code that requires the usage of a default constructor. In non-associative types (list/deque/vector), the loader seems to be calling the container's resize function with a default value_type argument, resulting in the attempted creation of the object through the default constructor. In associative types, the loader attempts to create a default constructed value_type, which results in an std::pair being defaultly constructed with one of the pieces being the non-default constructible type. The code below fails during compilation with the error "'A' : no appropriate default constructor available". It was built with MSVC++2013. #include <list> #include <fstream> #include <boost\archive\binary_iarchive.hpp> #include <boost\archive\binary_oarchive.hpp> #include <boost\serialization\access.hpp> #include <boost\serialization\list.hpp> class A { private: template<class Archive> void serialize(Archive &archive, unsigned int version) { archive & myInt; } friend boost::serialization::access; public: int myInt; A(int myInt) : myInt(myInt) {} A(const A &arg) : myInt(arg.myInt) {} A& operator=(const A &arg) { myInt = arg.myInt; return *this; } bool operator==(const A &arg) const { return myInt == arg.myInt; } }; namespace boost { namespace serialization { template<class Archive> inline void load_construct_data(Archive &archive, A *a, unsigned int file_version) { ::new(a)A(0); } } } int main() { { std::ofstream stream("file"); boost::archive::binary_oarchive archive(stream); std::list cont; cont.push_back(A(1)); archive << cont; } { std::ifstream stream("file"); boost::archive::binary_iarchive archive(stream); std::list cont; archive >> cont; } } My question is: is this behavior known and what is the best solution to this for an end-user? The tutorial for STL container serialization mentions using load/save_construct_data to get around this problem, yet the attempted code generation above do not take that solution into account so compilation will fail even if you overload those templates. The only solutions I can think of to circumvent this problem would be to require a public (the code ultimately fails in std code, which I guess you may be able to friend but would be quite strange) default constructor, or to hand-roll STL container serialization through non-intrusive serialize/save/load overloads and skip the provided overloads entirely. -- View this message in context: http://boost.2283326.n4.nabble.com/Serialization-STL-Containers-and-Non-Def… Sent from the Boost - Users mailing list archive at Nabble.com.

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How to create a subgraph of a graph with specified vertexes?
by ffmm3＠163.com 24 May '15

24 May '15

Hi, I have a graph with several vertexes and edges, now I want to creates a subgraph object with the specified vertex set. What should I do? 发自 Windows 邮件

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Is it Okay to Use the Boost Logo
by - 22 May '15

22 May '15

I tried to find out more about the licence for the logo but didn't get very far, but I now see that on Wikipedia the logo is also released under the Boost License so I presume that I can use it for my project page.

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Please help: boost::format and Borland C++ version 0x564 errors
by Royce 22 May '15

22 May '15

I'm trying to use boost::format with Borland C++ Builder 6 (Compiler version 0x564) and can't get the boost code to compile. The code was working with sprintf but I need to be able to use numbered args (i.e. "The first string is %1% and the second string is %2%." ) for localization so that the language translators can change the position the arguments appear in the translated text. I get an "E2270 > expected" error in line of integral_c.hpp (boost 1_45_0). which is template< bool C > The code near the error is: #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) \ && !BOOST_WORKAROUND(__BORLANDC__, <= 0x551) BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_OPEN // 'bool' constant doesn't have 'next'/'prior' members template< bool C > struct integral_c<bool, C> { BOOST_STATIC_CONSTANT(bool, value = C); typedef integral_c_tag tag; . >From what I can tell I should not have to define BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION, and defining it I breaks working code. I did find a reference to a bug that affects version Borland compiler versions 0x561 to 0x580 and I tried defining BOOST_BCB_PARTIAL_SPECIALIZATION_BUG. That did not help, but at least it didn't break anything. I am able to create a small test project and it works. I was able to get the same basic code to work in 50 or 60 places in 21 of the 23 *.cpp units in my primary project. This worked in my test code but broke in my main project. std::stringstream ss; ss << boost::format(LoadStr(STestWithString).c_str()) % "First" % "Second"; AnsiString translatedMsg = AnsiString(ss.str().c_str()); ShowMessage(translatedMsg); This also worked in my test program, but broke in my main project. std::string sRawMsg; AnsiString sDebug1 = "testArg1"; AnsiString sDebug2 = "testArg2"; sRawMsg = (boost::format("Testing %1% was first. %2% was second.") % sDebug1.c_str() % sDebug2.c_str()).str(); // ignoreW8080(boost::none); // Suppress false warning - Compiles to a nop. Any suggestions on solving this problem would be greatly appreciated. Royce Fessenden White Knight Software <http://www.whiteknightsw.com/> www.WhiteKnightSw.com 417.766.1852 royce(a)fessenden.com

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