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

Compiler warns about 'reference to temporary' with iterator on shared memory map
by Rajalakshmi Iyer 21 May '12

21 May '12

Hello, Consider: typedef std::pair<int, int> value_type; typedef allocator<value_type, managed_shared_memory::segment_manager> ValueAllocator; typedef boost::interprocess::map<int, int, std::less<int>, ValueAllocator> A_map; class A { public: A() { /* Construct shared memory map */ } ~A() bool contains(int i); private: A_map* m_objA; }; inline bool A::contains(int i) { A_map::iterator itr = m_objA->find(i); return (itr != m_objA->end()); } Here, at the line A_map::iterator itr = m_objA->find(i); I see this warning: .../boost_1_49_0/include/boost/container/detail/tree.hpp:391:31: warning: returning reference to temporary [enabled by default] I dont see a reason for this. Can someone please point out if I am doing something wrong here? Thanks in advance, Regards, Raj -- Twitter: @Blismobile <http://twitter.com/#!/blismobile> BlisMobile Media 32 Percy Street, London W1T 2DE www.blismobile.com [image: BlisMobile] <http://www.blismobile.com/>[image: Follow on Twitter]<http://twitter.com/#!/blismobile>[image: Blis Website] <http://www.blismobile.com/> This communication is from BlisMobile Media, which is a trading name of Breeze Tech (UK) Ltd, a company registered in England and Wales with registered number 06455773. Its registered office is 32 Percy Street, London W1T 2DE, United Kingdom. This communication contains information that is confidential and may also be privileged. It is for the exclusive use of the intended recipient(s). If you are not the intended recipient(s), please (1) notify info(a)blismobile.com by forwarding this email and delete all copies from your system and (2) note that disclosure, distribution, copying or use of this communication is strictly prohibited. Email communications cannot be guaranteed to be secure or free from error or viruses. All emails sent to or from a Blismobile email account are securely archived and stored by an external supplier. This email does not constitute a contractual agreement; such agreements are in specified contractual or Insertion Order (IO) form only and exclusively contain all the terms to which Breeze Tech )UK) Ltd will be bound. To the extent permitted by law, Breeze Tech (UK) Ltd does not accept any liability for use of or reliance on the contents of this email by any person save by the intended recipient(s) to the extent agreed in a contract or Insertion Order. Opinions, conclusions and other information in this email which have not been delivered by way of the business of Breeze Tech (UK) Ltd are neither given nor endorsed by it.

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[MSM] What's the easiest way to share data between states in a Boost.MSM state machine?
by B. Tommy Jensen 08 May '12

08 May '12

As the subject indicates, I'm trying to find the best way to share data between states in a MSM state machine. My first attempt has been to let each sub-machine and state inherit from a common base class, e.g.: struct MyStateMachine_ : public msm::front::state_machine_def<MyStateMachine_,CommonBaseClass> My idea is to add a reference to some shared data in the base class, making it easy to access the shared data from any state. The shared data reference must be passed to the base class. Questions: 1. Is it possible to pass constructor parameters to the common base class' constructor? I have tried different options without success, it seems that the default constructor with no arguments is the only option. 2. If 1. is not possible, what is the best way to initialize the shared property correctly? For example an easy method to iterate over all defined states? (not only the active ones). I have tried to iterate over all states with get_state_by_id, but this method does not enter sub-machines' states. 3. In general, what is the preferred way of implementing shared data between state classes in Boost.MSM? It would have been natural to store the data in the root state, but I can't see that there is an easy way to get access to the root FSM. (only the "nearest parent" FSM in the hierarchy is passed to the various event handler methods). Regards, Tommy

2 4

fatal error C1001 with VS2010, boost 1.49, and shared_ptr.hpp
by Phillip Hellewell 01 May '12

01 May '12

I'm upgrading to boost 1.49 and getting this fatal error while compiling a source file that uses shared_ptr: 1>C:\mycomps\base\target\dependency\include\boost/smart_ptr/shared_ptr.hpp(362): fatal error C1001: An internal error has occurred in the compiler. 1> (compiler file 'msc1.cpp', line 1420) 1> To work around this problem, try simplifying or changing the program near the locations listed above. 1> Please choose the Technical Support command on the Visual C++ 1> Help menu, or open the Technical Support help file for more information Line 362 of shared_ptr.hpp is: shared_ptr( shared_ptr<Y> && r, typename boost::detail::sp_enable_if_convertible<Y,T>::type = boost::detail::sp_empty() ) Looks like the compiler is crashing with an access violation; any suggestions other than wait for a patch from Microsoft? I don't want to have to disable features like BOOST_HAS_RVALUE_REFS or BOOST_SP_NO_SP_CONVERTIBLE, but that may be my only choice :( Thanks, Phillip

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async_read_some
by Christer Borgqvist 01 May '12

01 May '12

Hi, Im playing around with the /boost_asio/example/http/server3 and using POST method. The bytes_transferred is 231, but thats only the header and ends with \r\n\r\n, need to read the rest. Sometimes i get bytes_transferred to 1032, the right amount of data, sometimes i get bytes_transferred = 231, but if i print the buffer_ i have all the 1032 bytes. Is it right that the bytes in the buffer_ and the bytes_transferred is not the same? appreciate any help. /christer void connection::handle_read(const boost::system::error_code& e, std::size_t bytes_transferred) { if (!e) { boost::tribool result; boost::tie(result, boost::tuples::ignore) = request_parser_.parse( request_, buffer_.data(), buffer_.data() + bytes_transferred); if (result) { request_handler_.handle_request(request_, reply_); boost::asio::async_write(socket_, reply_.to_buffers(), strand_.wrap( boost::bind(&connection::handle_write, shared_from_this(), boost::asio::placeholders::error))); } else if (!result) { reply_ = reply::stock_reply(reply::bad_request); boost::asio::async_write(socket_, reply_.to_buffers(), strand_.wrap( boost::bind(&connection::handle_write, shared_from_this(), boost::asio::placeholders::error))); } else { socket_.async_read_some(boost::asio::buffer(buffer_), strand_.wrap( boost::bind(&connection::handle_read, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred))); } }

3 2

Use boost::shared_ptr with boost::adaptors
by tolik levchik 01 May '12

01 May '12

The following code gives me segfault. But if `foo_ptr` is `foo*` it works fine. #include <vector> #include <boost/range/adaptor/indirected.hpp> #include <boost/range/adaptor/transformed.hpp> #include <boost/range/algorithm/for_each.hpp> #include <boost/bind.hpp> #include <boost/shared_ptr.hpp> struct foo{ foo(int _i): i(_i){} virtual void bar() const{ std::cout << "foo::bar::i " << i << std::endl; } int i; }; typedef boost::shared_ptr<foo> foo_ptr; //typedef foo* foo_ptr; foo_ptr trasform(int i){ return foo_ptr(new foo(i)); } int main(){ std::vector<int> vec; vec.push_back(1); using namespace boost::adaptors; using boost::bind; boost::for_each(vec | transformed(bind(&trasform, _1)) | indirected, bind(&foo::bar, _1)); } Is it expected behavior of adaptors ?

3 6

Making my UdpConnection class thread safe
by Chris Dunphy 30 Apr '12

30 Apr '12

I have implemented some connection classes, using Boost ASIO, to replace some low level C code in an application, and everything is working great, except for one problem. Basically, I have a UdpConnection class that does synchronous read and write, but it uses async methods to handle time-outs as per the boost examples. The problem is I can't figure out how to make it threadsafe. I have tried adding strands to the event handlers to make this class threadsafe (code below), but that isn't working. I suspect it is because of the way timeout is implemented. I have included my code in 4 classes in pastebin. Single threaded is working fine. I also have TcpConnection and UnixSocketConnection classes that don't need to be shared amongst multiple threads and they work fine. However, I can't get multi-threaded UDP code to work. Am I missing something? Sources below: * Connection.h && AsioConnection.h http://pastebin.com/Cbbw37gL * UdpConnection.h && UdpConnection.cpp http://pastebin.com/VLnHBnPs

1 0

[Boost.Optional] Compilation error with boost::optional in Boost 1.49 and GCC 4.4.6
by Jonathan Jones 30 Apr '12

30 Apr '12

Hello, The following code fails to compile when using GCC 4.4.6 and boost::optional from Boost 1.49: #include <boost/optional/optional.hpp> #include <boost/type_traits/is_convertible.hpp> struct grill { template<typename U> grill (U) {} }; template<typename T> struct bar { template<typename U> bar (U, typename boost::is_convertible<U,T>::type* = 0) {} }; void foo() { typedef bar<grill> data_type; boost::optional<data_type> opt; boost::optional<data_type> opt2(opt); // this line (void)opt2; } Here are the error messages (I apologize for the long lines, I shortened them as much as possible by truncating the header paths): type_traits/is_convertible.hpp: In instantiation of ‘const bool boost::detail::is_convertible_basic_impl<boost::optional_detail::optional_base<bar<grill> >&, grill>::value’: type_traits/is_convertible.hpp:329: instantiated from ‘const bool boost::detail::is_convertible_impl<boost::optional_detail::optional_base<bar<grill> >, grill>::value’ type_traits/is_convertible.hpp:452: instantiated from ‘boost::is_convertible<boost::optional_detail::optional_base<bar<grill> >, grill>’ optional/optional.hpp:604: instantiated from ‘boost::optional<T>::optional(const boost::optional<T>&) [with T = bar<grill>]’ optional.cpp:25: instantiated from here optional/optional.hpp:285: error: ‘boost::optional_detail::optional_base<T>::optional_base(const boost::optional_detail::optional_base<T>&) [with T = bar<grill>]’ is protected type_traits/is_convertible.hpp:170: error: within this context type_traits/is_convertible.hpp:170: error: initializing argument 1 of ‘grill::grill(U) [with U = boost::optional_detail::optional_base<bar<grill> >]’ optional/optional.hpp:308: error: ‘boost::optional_detail::optional_base<T>::~optional_base() [with T = bar<grill>]’ is protected type_traits/is_convertible.hpp:170: error: within this context This reproduction case is distilled from a real world example (not my code) where bar=boost::fusion::vector1 and grill=boost::function<void()> The code compiles fine using the same compiler and Boost 1.44. Any ideas on the root of the problem? Thanks in advance! Jon

2 4

Re: [Boost-users] [CMake] link error in Visual Studio when using boost from CMake
by Alain Leblanc 30 Apr '12

30 Apr '12

Don't have much experience with boost in combination with cmake, but don't you still need to add the boost libraries in a target_link_libraries() command? (Or whatever command is usedbto indicate the libraries to link with). A On Apr 30, 2012 2:49 PM, "Hui Wang" <huiwang8921(a)gmail.com> wrote: > Hello, > > I'm using CMake generated Visual Studio solution, and I added boost with > find_package(Boost), > before that I used commands: set(Boost_USE_STATIC_LIBS > ON) set(Boost_USE_MULTITHREADED ON) set(Boost_USE_STATIC_RUNTIME OFF) > after that I used > commands: include_directories(${Boost_INCLUDE_DIR}) add_executable( > MyProject src/main.cpp) > > Because automatic linking is used on Visual Studio when including Boost, > and it typically use static libraries, I try not to conflict with that. But > I get the error: > LINK : fatal error LNK1104: cannot open file > 'libboost_thread-vc100-mt-gd-1_47.lib' > > I installed pre-compiled binary Boost with the installer provided by > BoostPro Computing, and I checked to find that I do have > libboost_thread-vc100-mt-gd-1_47.lib, libboost_thread-vc100-mt-s-1_47.lib > libboost_thread-vc100-mt-sgd-1_47.lib libboost_thread-vc100-mt-1_47.lib > in C:\Program Files\boost\boost_1_47\lib > > I also output messages to find that > Boost_FOUND=TRUE Boost_LIBRARY_DIRS=C:/Program > Files/boost/boost_1_47/lib Boost_INCLUDE_DIRS=C:/Program > Files/boost/boost_1_47 > > So I'm confused why it has the link error. I tried with dynamically > linking too, it can't find the .dll files at runtime either, but again they > exist right there in the directory I installed boost. Could anyone help me > understand where the problem is? > > Thanks! > -- > Sophie Wang > www.sophiehuiwang.com > > > -- > > Powered by www.kitware.com > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Please keep messages on-topic and check the CMake FAQ at: > http://www.cmake.org/Wiki/CMake_FAQ > > Follow this link to subscribe/unsubscribe: > http://www.cmake.org/mailman/listinfo/cmake >

1 0

catch serial port events
by jellad tarek 30 Apr '12

30 Apr '12

hello can i detect a change in pin cts of com1 (in real time) and callback a function with to boost library???? thank you

1 0

get local time in microsecondes :-)
by jellad tarek 30 Apr '12

30 Apr '12

hello i want to get the local time in microseconds (no the diff between 2 times)... like wireshark or commview. in this format 15:23:10,251485 is it possible with the booooost library ?????? 1000 thanks

1 0