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[Signals] trackable detection for user defined callabcks
by Szymon Gatner 30 Oct '11

30 Oct '11

Hi, Signals docs say: "Warning: User-defined function objects and function objects from other libraries (e.g., Boost.Function or Boost.Lambda) do not implement the required interfaces for trackable object detection, and will silently ignore any bound trackable objects. Future versions of the Boost libraries will address this limitation." My questions: 1) What is the required interface for user-defined callbacks? 2) Is it still true that it will be addressed in future versions of Boost.Function? Regards, Simon -- Szymon Gatner The Lordz Games Studio www.thelordzgamesstudio.com

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[boost] [C++ Now! 2012] Call for Submissions
by Brian Wood 30 Oct '11

30 Oct '11

Hartmut Kaiser: > The C++ Now! Conference is dedicated to discussion and education > about C++, an open and free language and standard. It costs a lot to buy a copy of the standard now! Hope conference goes well and maybe I can attend someday. -- Brian Wood Ebenezer Enterprises http://webEbenezer.net

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Re: [Boost-users] sending large serialized objects over network
by Brian Wood 30 Oct '11

30 Oct '11

Jonathan Bishop: > HI, > I am involved in a project which requires the transport of large C++ > instances over MPI communication channels. I am using boost serialization to > pack and unpack the objects into a buffer. The whole buffer is sent in one > shot. > > Of course for large objects this can be problematic. I have two questions... > > 1) is there any way to tell beforehand how large the buffer needs to be? In > other words, can you run serialization in a counting only mode? I'm not sure about the Boost Serialization library, but the C++ Middleware Writer counts the number of bytes in a message before any is marshalled. Here's an example void remote_messages::Marshal (SendCompressedBuffer& buf , marshalling_integer const& abt1 , marshalling_integer const& abt2 , cmw_user_input const& abt3 ) { Counter cntr(msg_length_max); abt1.CalculateMarshallingSize(cntr); abt2.CalculateMarshallingSize(cntr); abt3.CalculateMarshallingSize(cntr); cntr.Add(sizeof(msg_id_direct)); buf.Receive(&msg_id_direct, sizeof(msg_id_direct)); abt1.Marshal(buf, false); abt2.Marshal(buf, false); abt3.Marshal(buf, false); } -- Brian Wood Ebenezer Enterprises http://webEbenezer.net <http://webebenezer.net/>

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split() and MSVS .NET 2003
by Larry 30 Oct '11

30 Oct '11

I have found using Boost 1.47 with MSVS .Net 2003 that if I include split() that it tends to kill the Intellisense function in the editor for a current method or function. I usually have something like typedef vector<string> Splits; Splits sv; string input_string; split(sv,input_string,is_any_of("|")); I was curious if anyone else had run across this and better yet if there was a way around it. I think I may have seen it in earlier Boost versions but my memory is fuzzy about that. There was a time when this behavior did not exist but I am not certain when and what MSVS changes may have been applied since it did work. The code compiles OK and works correctly. Larry

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Build error with boost-1.45.0 in ptree_implementation.hpp
by Sunil Thomas 29 Oct '11

29 Oct '11

Hi all! I am getting the following error with boost-1.45.0 using MS VS 2010 Profession, Win64 (Windows Vista 64 bit). Appreciate if anyone knows a fix. This error was seen with older versions like 1.41 and so on; hence, it must've been fixed by now. <path\to>\boost/property_tree/detail/ptree_implementation.hpp(30) : error C2440: 'specialization' : cannot convert from 'const std::string std::_Pair_base<_Ty1,_Ty2>::* ' to 'const std::basic_string<_Elem,_Traits,_Ax> std::pair<_Ty1,_Ty2>::* ' with [ _Ty1=const std::string, _Ty2=boost::property_tree::basic_ptree<std::string,std::string> ] and [ _Elem=char, _Traits=std::char_traits<char>, _Ax=std::allocator<char>, _Ty1=const std::string, _Ty2=boost::property_tree::basic_ptree<std::string,std::string> ] Standard conversion from pointer-to-member of base to pointer-to-member of derived is not applied for template arguments <path\to>\boost/property_tree/detail/ptree_implementation.hpp(78) : see reference to class template instantiation 'boost::property_tree::basic_ptree<Key,Data>::subs' being compiled with [ Key=std::string, Data=std::string ] <path\to>\boost/foreach.hpp(265) : see reference to class template instantiation 'boost::property_tree::basic_ptree<Key,Data>::const_iterator' being compiled with [ Key=std::string, Data=std::string ] libs\graph\src\graphml.cpp(36) : see reference to class template instantiation 'boost::foreach_detail_::auto_any<T>' being compiled with [ T=boost::property_tree::basic_ptree<std::string,std::string>::const_iterator ] Appreciate any help! Thanks, --Sunil.

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How efficient is the boost::regex library?
by Alec Taylor 29 Oct '11

29 Oct '11

Good afternoon, I am looking for the most efficient open-source C++ regex library. Reading this article: http://swtch.com/~rsc/regexp/regexp1.html - It seems that GNU awk is the best overall: http://pdos.csail.mit.edu/~rsc/regexp-img/grep1p.png How does the boost::regex library compare? Would you recommend boost::regex as the most efficient one, or would you suggest another? Thanks for all information, Alec Taylor

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[serialization] tracking objects
by Matthias Brantner 29 Oct '11

29 Oct '11

Hello, I have n objects sharing common (sub)objects in a pool (i.e. via pointers). I would like to save (serialize) these n objects separately. Each result should contain one copy of the shared object and can be used stand alone. However, when loading (deserializing) multiple of those n objects, I would like to recreate the original state, i.e. subobjects previously pooled are again shared and contained in the pool. For example, object O1 contains a pointer to object P1. Object O2 also contains a pointer to object P1. O1 and O2 are separately serialized and each serialization will contain a copy of P1. After deserializing, the deserialized versions of O1 and O2 should both contain pointers to the same object P1. My current idea is to deserialize P1 (in the process of deserializing O1 or O2) by implementing the load function for P1's class. In this function, I would like to check if an object equal to P1 already exists in the pool. If it exists, I would like to return a pointer to the existing object. Otherwise, I would like to insert it into the pool and return the newly created object. However, I have not found a way to return a pointer that was not created by boost. Is there such a way or is there a better way to do what I'm trying to do? Thanks in advance. Best regards Matthias

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Boost 1.47 and exception_ptr
by Travis Gockel 29 Oct '11

29 Oct '11

I'm working on upgrading from Boost 1.46.1 to 1.47 and having one tiny little problem with exception_ptr. Currently, some of my systems keep an exception_ptr around to denote if they have a "current exception" or not. At times, we need to "clear" the current exception (it was resolved or whatever), which we used to do by calling ex->reset(). However, as of 1.47, excecption_ptr is no longer just a shared_ptr, so reset() has gone away. What is the new preferred way of getting this old functionality? I can't seem to find the way in the source. -- Travis Gockel C++ Pirate

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Event system using signals2
by Chris Cranford 29 Oct '11

29 Oct '11

In the past, I have typically seen a lot of event systems leverage an abstract base listener class that all classes were derived from if they wanted to wire themselves up to a particular system, such as an event dispatcher. This lead to giant switch statements inside the listener's handle event method. I've used this methodology in the past and it has worked. But noticing that a number of articles have suggested using a signal/slot mechanism rather than the above approach, I started trying to implement a simple event dispatcher based on boost signals2; however I cannot seem to make it work as I would like. See code below: // holds relationship of type and signal object struct event_signal { int type; boost::signals2::signal<void(void)> sig; }; typedef struct event_signal event_signal_t; class EventDispatcher { // other stuff left out public: void addListener(int type, boost::function<void(void)> pFunction) { std::map<int,even_signal_t*>::iterator i = m_events.begin(); if(i == m_events.end()) { event_signal_t* p = new event_signal_t; p->type = type; p->sig.connect(p); m_events.insert(std::make_pair(type, p)); } else { m_events[type]->sig.connect(pFunction); } } private: std::map<int, event_signal_t*> m_events; }; Since signals are not copyable, I had to store a pointer to a signal. I chose a struct in case I want to add more information later; however I could have easily used the signal directly. The classes that I want to wire to my event dispatcher must derive from boost::signals2::trackable because I want their connection to be automatically deleted upon the tracked object's destruction; so here is my tracked object: // base class for event system tracking class EventTrackedObject : public boost::signal2::trackable { public: EventTrackedObject() { } ~EventTrackedObject() { } }; class MyObject : public EventTrackedObject { public: MyObject(EventDispatcher* pDispatcher) { pDispatcher->addListener(E_MY_EVENT, boost::bind(&MyObject::OnMyEvent, this)); } ~MyObject() { } void OnMyEvent(void) { } }; The problem with this I found is that the tracked object appears to be getting copied at the time the boost::bind is passing itself to the addListener() method. Is there a way to avoid this so that the tracked object's disconnect happens as expected? Secondly, I would prefer not to have to reference this and use the bind call at all in my base objects and rather simply have a call that looks like: pDispatcher->addListener(E_MY_EVENT, &MyObject::OnMyEvent); Or is there a more ideal approach to my problem that I am missing? Chris

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Problem compiling
by Matteo 28 Oct '11

28 Oct '11

Hi guys, I am writing a class that include gboy's libraries ( http://gobysoft.com/#/software/goby) but I have a problem with boost libraries. The code is: (from gobymodule.cc) void GobyModule::start() { // // 1. Create and initialize MMDriver // // goby::acomms::ModemDriverBase* driver = 0; goby::acomms::protobuf::DriverConfig cfg; // set the serial port given on the command line cfg.set_serial_port(serial_path); using google::protobuf::uint32; // set the source id of this modem // uint32 our_id = goby::util::as<uint32>(argv[2]); cfg.set_modem_id(ID); goby::glog.set_name("WHIO Micromodem"); goby::glog.add_stream(goby::util::logger::DEBUG1, &std::clog); // default to WHOI MicroModem // if (!driver) // { std::cout << "Starting WHOI Micro-Modem MMDriver" << std::endl; driver = new goby::acomms::MMDriver; // turn data quality factor message on // (example of setting NVRAM configuration) cfg.AddExtension(micromodem::protobuf::Config::nvram_cfg, "DQF,1"); // } /////////////////////////////////////// // THE PROBLEM IS HERE ///////////////////////////////////// function_pointer = &handle_data_receive; goby::acomms::connect(&driver->signal_receive, function_pointer); // // 2. Startup the driver // driver->startup(cfg); } (from gobyModule.h) class GobyModule: { public: void function(str::string); } void (*function_pointer)(const goby::acomms::protobuf::ModemTransmission & data_msg, GobyModule* foo); void handle_data_receive(const goby::acomms::protobuf::ModemTransmission & data_msg, GobyModule* foo) { foo->payload_parser(str.str()); } The problem, compiling, is: In file included from /usr/include/boost/function/detail/maybe_include.hpp:18:0, from /usr/include/boost/function/detail/function_iterate.hpp:14, from /usr/include/boost/preprocessor/iteration/detail/iter/forward1.hpp:52, from /usr/include/boost/function.hpp:64, from /usr/include/boost/thread/future.hpp:20, from /usr/include/boost/thread.hpp:24, from /usr/local/include/goby/acomms/modemdriver/driver_base.h:23, from /usr/local/include/goby/acomms/modem_driver.h:23, from gobyModule.h:10, from gobyModule.cc:1: /usr/include/boost/function/function_template.hpp:913:60: instantiated from ‘void boost::function1<R, T1>::assign_to(Functor) [with Functor = void (*)(const goby::acomms::protobuf::ModemTransmission&, GobyModule*), R = void, T0 = const goby::acomms::protobuf::ModemTransmission&]’ /usr/include/boost/function/function_template.hpp:722:7: instantiated from ‘boost::function1<R, T1>::function1(Functor, typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type) [with Functor = void (*)(const goby::acomms::protobuf::ModemTransmission&, GobyModule*), R = void, T0 = const goby::acomms::protobuf::ModemTransmission&, typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type = int]’ /usr/include/boost/function/function_template.hpp:1064:16: instantiated from ‘boost::function<R(T0)>::function(Functor, typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type) [with Functor = void (*)(const goby::acomms::protobuf::ModemTransmission&, GobyModule*), R = void, T0 = const goby::acomms::protobuf::ModemTransmission&, typename boost::enable_if_c<boost::type_traits::ice_not<boost::is_integral<Functor>::value>::value, int>::type = int]’ /usr/include/boost/signals/slot.hpp:111:122: instantiated from ‘boost::slot<SlotFunction>::slot(const F&) [with F = void (*)(const goby::acomms::protobuf::ModemTransmission&, GobyModule*), SlotFunction = boost::function<void(const goby::acomms::protobuf::ModemTransmission&)>]’ /usr/local/include/goby/acomms/connect.h:35:11: instantiated from ‘void goby::acomms::connect(Signal*, Slot) [with Signal = boost::signal<void(const goby::acomms::protobuf::ModemTransmission&)>, Slot = void (*)(const goby::acomms::protobuf::ModemTransmission&, GobyModule*)]’ gobyModule.cc:404:66: instantiated from here /usr/include/boost/function/function_template.hpp:112:11: error: too few arguments to function Thank you so much, Matteo

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