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boost threads and Qt
by Rainer Thaden 27 Mar '08

27 Mar '08

Hi all, I have a general question regarding threads and signals with boost and Qt. I have a DLL communicating with an external device via Ethernet and a main program with a Qt-GUI for controlling the device. The communciation runs in a different thread than the main program. Qt provides signal/slots across threads, but as I understand it, I have to use the QThread library for it to work. In the DLL I use boost signals and slots and the main program also receives boost signals and then emits Qt's signals to update the GUI, etc. The reason to not use Qt in the DLL was to not force other programmers to use Qt if they want to write their own control application for the DLL. However, I am getting in trouble with synchronization of the threads now and the question is: is it possible / recommended / not recommended to mix Qt's thread API with the boost thread API? Qt provides the possibility of "delayed" signals, that is, a posted signal is queued into the event loop of a thread and, thus, serialized. Is that easily possible with boost threads? Any comments appreciated. Best regards, Rainer

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Boost signals link error
by Michael Dugan 27 Mar '08

27 Mar '08

Hi I am using boost(1.34.1) signals on linux(centos5) with gcc 4.1.2. I can link to the static boost_signals-gcc41-mt library, however the following symbols seem to be missing. They all seem to be related to boost::signals::named_slot_map_iterator. Other symbols such as boost::signals::connection::~connection() are found. ../../../bin/x86_64/32/linux/g++4.1.2/release/libIceExchangeCommon.so: undefined reference to `boost::signals::detail::named_slot_map_iterator::named_slot_map_iterato r(boost::signals::detail::named_slot_map_iterator const&)' ../../../bin/x86_64/32/linux/g++4.1.2/release/libIceExchangeCommon.so: undefined reference to `boost::signals::detail::named_slot_map_iterator::operator=(boost::signa ls::detail::named_slot_map_iterator const&)' ../../../bin/x86_64/32/linux/g++4.1.2/release/libIceExchangeCommon.so: undefined reference to `boost::signals::detail::named_slot_map_iterator::dereference() const' ../../../bin/x86_64/32/linux/g++4.1.2/release/libIceExchangeCommon.so: undefined reference to `boost::signals::detail::named_slot_map_iterator::increment()' ../../../bin/x86_64/32/linux/g++4.1.2/release/libIceExchangeCommon.so: undefined reference to `boost::signals::detail::named_slot_map_iterator::equal(boost::signals:: detail::named_slot_map_iterator const&) const' collect2: ld returned 1 exit status Has anyone seen this before? Thanks in advance. Michael Schneider Trading 4th Floor, 25 Copthall Avenue London EC2R 7BP -------------------------------------------------------- Message from: Michael.Dugan(a)schneidertrading.com Message to: boost-users(a)lists.boost.org Attached files: 0 This e-mail and any files transmitted with it are confidential, may be legally privileged, and are for the sole use of the intended recipient. Copyright in this e-mail and any accompanying document created by us is owned by us. If you are not the intended recipient of this e-mail or any part of it please telephone our IT Department at the number shown above or by e-mail at info(a)schneidertrading.com. You should not use or disclose to any other person the contents of this e-mail or its attachments (if any), nor take copies. This e-mail is not a representation or warranty and is not intended nor should it be taken to create any legal relations, contractual or otherwise. Schneider Trading Associates Ltd (Registration No. 3692131) is incorporated in England and Wales and the registered office is at 25 Copthall Avenue, London EC2R 7BP. The company is authorised and regulated by the Financial Services Authority

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Re: [Boost-users] Ugly warnings from BOOST_STATIC_ASSERT
by Jean-Francois Bastien 27 Mar '08

27 Mar '08

> We have this really neat and simple macro in our project: > #define compile_assert(x) typedef bool > COMPILE_ASSERT[(x) ? 1 : -1] > > Although it does what we need and serves us well, I > tried to replace > it with BOOST_STATIC_ASSERT. Unfortunately this resulted > in a lot of > ugly warnings throughout the compile: > warning: use of old-style cast > There's the following comment in the static assert header: // Note that the argument to the assert is explicitly cast to bool using old- // style casts: too many compilers currently have problems with static_cast // when used inside integral constant expressions. The solution would be to add even more defines to use old style or static casts depending on which compiler is used. JF

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Pointer types that let me specify destructor functions.
by Jason Cipriani 27 Mar '08

27 Mar '08

The boost shared_ptr lets me specify my own destructor function, but shared_ptr does more than I want -- I do not need thread-safety or reference counting, and would like to avoid the associated overhead. What I really want is an std::auto_ptr that lets me specify a destructor function. Does boost have something light-weight like this? Right now I implement my own, sort of like this (with extra conversion stuff): template <class T> class auto_ptr_ex { public: typedef void (* D) (T *); // object + destructor auto_ptr_ex (T *t, D d) : t_(t), d_(d) { } // copied auto_ptr_ex's don't destroy t_ auto_ptr_ex (const auto_ptr_ex &a) : t_(a.t_), d_(NULL) { } ~auto_ptr_ex () { if (d_) d_(t_); } private: T *t_; D d_; }; It's simple enough but I try not to reinvent wheels, so I was wondering if it existed already. Thanks, Jason

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GSoC Projects
by Derrick Hathaway 27 Mar '08

27 Mar '08

Hello, I wonder if some of you who may have had experience with Google's Summer of Code program could give me a little direction. I have an idea which projects I will be applying for. But I had a few questions. First of all, do I need to find a mentor who has already been accepted into the program before I apply? Or, is that part of the deciding factor for being accepted (wether or not there is a mentor for the proposed project)? There are a couple of projects listed in the Boost Wiki [http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?Google_Summe…] that I am interested in applying for. I have been using the Boost libraries for a few years now and am anxious for an opportunity to give back. My senior project [http://derrickhathaway.googlepages.com/gsi_mds.tar.gz] is a market data server based upon ASIO and I'm particularly interested in the projects related to that library. I have communicated a little with Michael Dickey who is involved in the development of the Pion Network Library [http://www.pion.org/projects/pion-network-library] He is also working now with the developers of the C++ Network Library [http://sourceforge.net/projects/cpp-netlib] This is one of the GSoC projects I will be proposing/applying for. He has been very helpful, but suggested that I inquire of those who may be involved with Google Summer of Code already. Thanks in advance, Derrick

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[Proto] Reminder: review will end March 28th
by Hartmut Kaiser 27 Mar '08

27 Mar '08

Hi all, this is just a gentle reminder for all intending to write a Proto review to finish it really soon. At the same time this should be understood as an encouragement for all of you still hesitating to write one because you perhaps think the library is too complicated or too exotic and you probably won't be able to write an adequate review. Please do not hesitate! Even a short review based on your experience or based on what you've read in the documentations is highly appreciated. Please consider writing your review not later than March 28th. If you won't be able to finish it in time but still intend to write a review, please contact me directly so we can work out the details. Regards Hartmut Review manager

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boost::filesystem::path and Windows CreateFile()
by pashapal＠aol.com 27 Mar '08

27 Mar '08

Hi, I was hoping someone could help, cause I am stumped. I have a library that opens disk images (img, dd, raw) via a string representing the file of the disk image. I supply the string as the lead argument in the constructor of boost::filesystem::path p(pImagePath, boost::filesystem::no_check) ; It works on?all?platforms tested. However, now I want to open a physical drive directly, rather than an image file in Windows. I have looked up the string representation of drives in Win 32 and apparently //./X: , however, it does not work with the path constructor. I have tried variations with the backslash etc. Windows allows access to a drive through the CreateFile() function, can I use this somehow and convert it into a boost::path? Any idea what I am doing wrong? In essences I want to access a windows drive as a boost::filesystem::path, that I can then later use for memory mapping. Thanks , Pasha boost::filesystem::path p(pImagePath, boost::filesystem::no_check) ; It works on?all?platforms tested. However, now I want to open a physical drive directly, rather than an image file in Windows. I have looked up the string representation of drives in Win 32 and apparently //./X: , however, it does not work with the path constructor. I have tried variations with the backslash etc. Windows allows access to a drive through the CreateFile() function, can I use this somehow and convert it into a boost::path? Any idea what I am doing wrong? In essences I want to access a windows drive as a boost::filesystem::path, that I can then later use for memory mapping. Thanks , Pasha

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Containers question
by James Sutherland 26 Mar '08

26 Mar '08

Fellow boost enthusiasts, I want to be able to store a set of information that contains types. For example: > template<typename T> > void register_field( const FieldID id ) > { > // need to keep a record of (T,id) > } Later on, I need to recover the type and id (T,id) for use. Any thoughts on a way to accomplish this? Thanks for any advice, James

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generic data assign
by Olaf Peter 26 Mar '08

26 Mar '08

Hello, how can I make the snipped more generic in that way, that I can use it with different data members, e.g. as template argument the &actions::m_data::text data address. Then I could write e.g. set_generic<&actions::m_data::text, std::string> set_text; Thanks, Olaf ---8<--- #include <iostream> #include <string> struct data { std::string text; }; struct actions { explicit actions(data& d) : set_text( *this ), m_data( d ) { } template<typename T> struct set_generic { explicit set_generic( actions& actions ) : self( actions ) { } void operator()(const T& data) const { self.m_data.text = data; } private: actions& self; }; set_generic<std::string> set_text; set... data& m_data; }; using namespace std; int main() { data d; actions a( d ); a.set_text( "Hello" ); cout << d.text << endl; } --->8---

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Re: [Boost-users] serialization and ::copyFrom
by Andrei Popa 26 Mar '08

26 Mar '08

Robert Ramey wrote: > Oh, that should be easy: > > D1 *d1p; > > ar << d1; > ar >> *d1p; > > Robert Ramey Hi,At> ar << d1;> ar >> bp; // but "bp" points already to an object of type D1I meant : "bp" is "Base* bp"So, if I call ar >> *bp; the Base::load will be called, not the derived D1:load.Actually more precisely, I intend to do solass Base { ... virtual .. } class D1 : public Base { } Base* bp1 = new D1(..some thing..); Base* bp2 = new D1(..some thing else..); ar << *bp1; ar >> *bp2; This means for all my serializable classes I have a kind of "=" operator defined. regards, Andrei _________________________________________________________________ Invite your mail contacts to join your friends list with Windows Live Spaces. It's easy! http://spaces.live.com/spacesapi.aspx?wx_action=create&wx_url=/friends.aspx…

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