- Boost-users - lists.boost.org

[serialization][python] (ab)using serialization to read/write object attribute values from python
by Václav Šmilauer 16 Jul '09

16 Jul '09

Hello boosters, I am working on http://yade.wikia.com project and we plan to switch to boost::serialization. boost::python is already used (many thanks for that fantastic piece of code). Let me explain the current state first. We use custom serialization interface: each class registers various attributes of objects; at serialization, archive of pointers to the attributes associated with attribute names is created and serialized to XML (and vice versa for deserialization). Boost.python is used to wrap c++ objects in python. Each wrapper class defined __getattr__ and __setattr__; if called, the wrapper: 1. Checks that the underlying c++ object has an associated archive of attributes created. 2. Gets/sets the value of the attribute based on its registered name (because of current limitations, the value is passed to the archive as string) The advantage is that there is no need to wrap every single class in python, just a few top-level classes; and access to all other attributes of the derived types is automatically provided by the serialization framework. My questions are: 1. Do boost::serialization archives keep pointers to attributes, in such way that it is possible to keep one archive instance per object and use it to write an attribute continuously, with the change being immediately propagated to the c++ objects, and ask the archive for attribute value based on its name? 2. Is it possible (or has it even been done) to define python_iarchive and python_oarchive that would (de)serialize between python and c++ types (such as std::map to dicitonary, [] to vector etc.)? I am sorry if those questions are trivial or nonsensical... I am trying to foresee problems that we could have with boost::serialization. If you have some proposition how to solve this xml+python attribute access in a better unified way, don't hesitate to post, please. (Switching the wrapper to py++ doesn't seem very practical at the moment, as it works quite nicely the current way; (frequent) adding of a class or adding/removing attributes doesn't require the wrapper to be regenerated/recompiled at all) Regards, Václav Šmilauer

1 0

Building boost faster: /MP
by Robert Dailey 16 Jul '09

16 Jul '09

Hello, I'm sure most of you are aware of the /MP flag introduced in MSVC9. I know this flag works fine when set through Visual Studio 9, however, I'm not sure if it works when calling cl.exe directly. Since it's just a compiler flag I imagine it does. It would be great to see support for this flag in CMake and/or bjam to help build boost faster when using this particular compiler. Any thoughts on this? Sincerely, Robert Dailey

6 10

A question on C++ DLL making in Dev-C++.Can anyone with kindness help me?
by fmingu 16 Jul '09

16 Jul '09

I am using Dev-C++ 4.9.8.0. I tried to make DLLs in Dev-C++. Can anyone with kindness tell me where can I get the help materials on making classes in a DLL and use the member functions in my executables? I found many materials spoke on the functions in DLL but few of them spoke on the member functions and classes in DLL. Although the platform gives the skeleton of a C++ DLL,i.e. dllmain.cpp, dll.h,I can not understand it. The help files in Dev-C++ did not explain it explicitly. Maybe a step_by_step turial is useful. I know that is not quite appropriate to ask such question in this area. But after several days of asking problems, I found there are lots of experts here. And I am just a new comer in programing. Does someone know the format of DLL made from Dev-C++ ? Coff or omf ? Can the DLL be applied by Borland C++ builder 2009? If not, how can I handle it? Can the DLL be compatible with Visual C++? Thanks a lot.

2 1

Re: [Boost-users] Unable to catch exception using boost::asio
by Alex Black 15 Jul '09

15 Jul '09

> > Message: 3 > Date: Wed, 15 Jul 2009 10:56:22 -0500 > From: Zachary Turner <divisortheory(a)gmail.com> > Subject: Re: [Boost-users] Unable to catch exception using boost::asio > To: boost-users(a)lists.boost.org > Message-ID: > <478231340907150856x12c9fd92w3b06630d349eef36(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > > I wrapped my call to run() in a try-catch, no luck, no exception > > appears to be being thrown by io_service.run(). > > > > void CBaseWebServer::RunIoService() > > { > > ? ? ? ?try > > ? ? ? ?{ > > ? ? ? ? ? ? ? ?m_IoService.run(); > > ? ? ? ?} > > ? ? ? ?catch ( ... ) > > ? ? ? ?{ > > ? ? ? ? ? ? ? ?cout << "Unhandled exception in > RunIoService"; ? ? ? ?} > > } _______________________________________________ > > Boost-users mailing list > > Boost-users(a)lists.boost.org > > http://lists.boost.org/mailman/listinfo.cgi/boost-users > > > > > That probably won't help. Notice that > CBaseWebServer::RunIoService() is not in the call stack at > the point you're seeing the exception. > After looking at your callstack again, I believe you're > throwing from a destructor. In particular, notice in your > callstack that you have > this: > > 26 ~ProtoBufStreamAdaptor() /home/noirs/workspace/myfile2.cpp:10 > 0x000000000042c6e5 > 25 CWebServer::HandleGetNeighbors() > /home/noirs/workspace/myfile3.cpp:215 0x000000000041d2d8 > > > These appear to both be in your own code. My suspicion is > that an exception occurs in CWebServer::HandleGetNeighbors(), > which causes it to unwind the stack and execute destructors. > In particular a destructor for an object of type > ProtoBufStreamAdaptor() is called, and this destructor then > throws another exception. At this point your program will > definitely terminate immediately. > > First check the destructor of ProtoBufStreamAdaptor() to see > why it's throwing (destructors should _never_ throw under any > circumstances), and then check the code of > CWebServer::HandleGetNeighbors() to find the original error. Thanks for continuing to help with this. I had the same thoughts as you, and I've looked into that with no luck. For example, here is the code for ~ProtoBufStreamAdaptor(): ProtoBufStreamAdaptor::~ProtoBufStreamAdaptor(void) {} The original error is related to the client (on the other end of the socket) being interrupted. Presumably some socket operation is throwing an exception, e.g. I'm writing to the socket after the client has disconnected. You mentioned never throwing exceptions in destructors - sounds like good advice, thx. Two points though: 1. If an exception is thrown in a destructor can it not be caught with a try catch( ... )? 2. I'll look over the code more closely and see if there are any destructors throwing.

3 9

Serialization on boost::dynamic bitset
by Gokulakannan Somasundaram 15 Jul '09

15 Jul '09

Hi, I have to write code for serialization of dynamic bitset. I could well write the code by iterating through the bitset, but i was just wondering, why it is not provided as part of the library. Thanks, Gokul.

1 1

using bjam to build multi thread library for visual studio 2003
by mike_wilson 15 Jul '09

15 Jul '09

Hi, I am trying to build the multi thread library for visual studio 2003. I built the bjam exe and run the following. bjam toolset=msvc-7.1 variant=debug threading=multi link=shared but I am returned C:\boost>bjam toolset=msvc-7.1 variant=debug threading=multi link=shared C:/boost/tools/build/v2/tools\msvc.jam:734: in configure-really *** argument error * rule path.make ( native ) * called with: ( ) * missing argument native C:/boost/tools/build/v2/util\path.jam:44:see definition of rule 'make' being called C:/boost/tools/build/v2/tools\msvc.jam:184: in configure C:/boost/tools/build/v2/tools\msvc.jam:137: in msvc.init C:/boost/tools/build/v2/build\toolset.jam:38: in toolset.using C:/boost/tools/build/v2/build\project.jam:862: in using C:\boost\tools/build/v2\user-config.jam:59: in modules.load C:/boost/tools/build/v2\build-system.jam:241: in load-config C:/boost/tools/build/v2\build-system.jam:383: in load-configuration-files C:/boost/tools/build/v2\build-system.jam:520: in load C:\boost\tools\build\v2/kernel\modules.jam:283: in import C:\boost\tools\build\v2\kernel\bootstrap.jam:138: in boost-build C:\boost\boost-build.jam:18: in module scope My bjam version is C:\boost>bjam --version Boost.Build V2 (Milestone 12) Boost.Jam 03.1.17 and my boost library version is 1.38. My boost library is in c:\boost so no spaces present in directory paths. Thanks for any advice. -- View this message in context: http://www.nabble.com/using-bjam-to-build-multi-thread-library-for-visual-s… Sent from the Boost - Users mailing list archive at Nabble.com.

1 0

boost mutex locks
by mike_wilson 15 Jul '09

15 Jul '09

Hi, I am a newbie to C++ multi threading (did a bit in java) and would like for information on the following... consider:- class MyClass { void SetMyObject(SomeClass const& value) { boost::mutex::scoped_lock lock(objectMutex); myObject = value; } SomeClass SetMyObject() const { boost::mutex::scoped_lock lock(objectMutex); return myObject; } private: SomeClass myObject; boost::mutex objectMutex; }; Say one thread accesses the SetMyObject() , given that there is a lock in the function, it will also lock the GetMyObject() blocking any other thread from calling? This kind of implies that wherever in the object there is a lock, any function owned by the object will be locked to any other thread trying to access. Is this correct? Thanks again for your help. -- View this message in context: http://www.nabble.com/boost-mutex-locks-tp24406812p24406812.html Sent from the Boost - Users mailing list archive at Nabble.com.

4 3

Re: [Boost-users] Unable to catch exception using boost::asio
by Alex Black 15 Jul '09

15 Jul '09

(Response below) > > Alex Black wrote: > > (Response is below) > > > > > >> On Tue, Jul 14, 2009 at 7:49 PM, Alex > Black<alex(a)alexblack.ca> wrote: > >>>>> I'm using boost::asio for sockets, writing a response out to a > >>> client. > >>>>> If the client stops part way through getting the > >> response, then my > >>>>> server process dies: > >>>>> > >>>>> terminate called after throwing an instance of > >>>>> > >> > 'boost::exception_detail::clone_impl<boost::exception_detail::error_in > >>>>> fo_injector<boost::system::system_error> > >>>>>> ' > >>>>> ? what():? Broken pipe > >>>>> > >>>>> The code though is surrounded by try catch like this: > >>>>> > >>>>> try > >>>>> { > >>>>> ??? ... > >>>>> } > >>>>> catch ( std::exception& e ) > >>>>> { > >>>>> ??? cout << e.what() << endl; > >>>>> } > >>>>> catch ( ... ) > >>>>> { > >>>>> ???? cout << "unexpected exception" << endl; } > >>>>> > >>>>> How do I prevent my process from aborting/terminating like this? > >>> v > >>> > >>>> Have you verified that the code inside the try block > executes on the > >>> same thread that the exception is occuring in? > >>> > >>> Not explicitly, how would I do that? > >>> > >>> thx > >>> > >> First put a breakpoint inside the try block. When it gets > >> hit use whatever mechanism your debugger provides to see what > >> thread you're in. In windows using MSVC, for example, you'd > >> just add a watch for a variable called $TID which a special > >> pseudo-variable that shows you the thread id. For other > >> debuggers you'd have to consult the manual. > >> Next register an unhandled exception handler. > >> > >> #include <exception> > >> > >> void unhandled_exception_handler() > >> { > >> std::cout << "Got an unhandled exception!" << std::endl; } > >> > >> int main(int argc, char** argv) > >> { > >> std::set_terminate(unhandled_exception_handler); > >> > >> //rest of your program. > >> } > >> > >> Then put a breakpoint inside unhandled_exception_handler and > >> when it gets hit walk up the callstack in the debugger to see > >> where the exception is occuring. In addition you can > >> determine the thread id again using the same method you used > >> in the first step. My guess is that they're not in the same > >> thread. I'm not sure if it applies to your scenario, but > >> remember that the operation's completion handler is invoked > >> on is not necessarily the same thread that the request is > >> issued on depending on how you're using the io_service > >> object. So while you have a try {} catch(...) {} in the > >> completion handler, if the exception is on the other thread > >> that does you no good. > >> > > > > Thanks for the tip, I didn't know about set_terminate, I made that > > change. > > > > I put a breakpoint in my terminate handler, and the callstack looks > > like: > > > > 32 unhandled_exception_handler() /home/noirs/workspace/myfile.cpp:35 > > 0x0000000000438764 > > 31 <symbol is not available> 0x00007f9ceb0d04b6 > > 30 <symbol is not available> 0x00007f9ceb0cf6ab > > 29 __gxx_personality_v0() 0x00007f9ceb0d0278 > > 28 <symbol is not available> 0x00007f9ceab7cff3 > > 27 _Unwind_Resume() 0x00007f9ceab7d0b8 > > 26 ~ProtoBufStreamAdaptor() /home/noirs/workspace/myfile2.cpp:10 > > 0x000000000042c6e5 > > 25 CWebServer::HandleGetNeighbors() > > /home/noirs/workspace/myfile3.cpp:215 0x000000000041d2d8 > > 24 CWebServer::OnHttpRequest() /home/noirs/workspace/myfile3.cpp:89 > > 0x000000000041e790 > > 23 CBaseWebServer::HandleHTTPRequest() > > /home/noirs/workspace/myfile4.cpp:92 0x00000000004092ef > > 22 CBaseWebServer::HandleAccept() > /home/noirs/workspace/myfile4.cpp:61 > > 0x0000000000409a9e > > > > HandleAccept looks like: > > > > void CBaseWebServer::HandleAccept(shared_ptr<tcp::socket> > pSocket, const > > boost::system::error_code& error) > > { if ( !error ) > > { > > try > > { > > HandleHTTPRequest(pSocket); > > > > StartAccept(); > > } > > catch ( ... ) > > { > > cout << "Unhandled exception in HandleAccept"; > > } > > } > > else > > { > > cout << "HandleAccept received error: " << > > error.message().c_str() << endl; > > } > > } > > _______________________________________________ > > Boost-users mailing list > > Boost-users(a)lists.boost.org > > http://lists.boost.org/mailman/listinfo.cgi/boost-users > > Um, broken pipe = closed file desciptor. > > Check if the socket is actually valid in the shard_ptr... > > BTW, are you using Async operations.... if so then the exception will > not originate from your code but from io_service.run(). I wrapped my call to run() in a try-catch, no luck, no exception appears to be being thrown by io_service.run(). void CBaseWebServer::RunIoService() { try { m_IoService.run(); } catch ( ... ) { cout << "Unhandled exception in RunIoService"; } }

2 1

[statechart] Substates in dll
by Bill Clark 15 Jul '09

15 Jul '09

Is there any way to partition a state machine using boost::statechart such that the main state machine is in one dll, and its substates (and possibly their substates) are in separate dll's? It would seem that this would create a cyclic dependency. Suppose you have e.g. a simple statechart called MyStatechart containing an initial state State1 which transitions to State2 in response to some event. Is it possible to implement MyStatechart and State1 in MyStatechart.dll, and State2 in State2.dll? Since the code for State1 will need to reference State2 (in order to transition to it), MyStatechart.dll will have a dependency on State2.dll. But since State2 is contained in MyStatechart, its type will have to look something like struct State2: sc::state<State2, MyStatechart> { //... }; which means that State2.dll will have a dependency on MyStatechart.dll. Is it possible to avoid this cycle? Thanks for any help, Bill

3 7

Re: [Boost-users] Unable to catch exception using boost::asio
by Alex Black 15 Jul '09

15 Jul '09

(Response is below) > On Tue, Jul 14, 2009 at 7:49 PM, Alex Black<alex(a)alexblack.ca> wrote: > >>> I'm using boost::asio for sockets, writing a response out to a > > client. > >>> > >>> If the client stops part way through getting the > response, then my > >>> server process dies: > >>> > >>> terminate called after throwing an instance of > >>> > > > 'boost::exception_detail::clone_impl<boost::exception_detail::error_in > >>> fo_injector<boost::system::system_error> > >>>>' > >>> ? what():? Broken pipe > >>> > >>> The code though is surrounded by try catch like this: > >>> > >>> try > >>> { > >>> ??? ... > >>> } > >>> catch ( std::exception& e ) > >>> { > >>> ??? cout << e.what() << endl; > >>> } > >>> catch ( ... ) > >>> { > >>> ???? cout << "unexpected exception" << endl; } > >>> > >>> How do I prevent my process from aborting/terminating like this? > > v > > > >>Have you verified that the code inside the try block executes on the > > same thread that the exception is occuring in? > > > > Not explicitly, how would I do that? > > > > thx > > > > First put a breakpoint inside the try block. When it gets > hit use whatever mechanism your debugger provides to see what > thread you're in. In windows using MSVC, for example, you'd > just add a watch for a variable called $TID which a special > pseudo-variable that shows you the thread id. For other > debuggers you'd have to consult the manual. > Next register an unhandled exception handler. > > #include <exception> > > void unhandled_exception_handler() > { > std::cout << "Got an unhandled exception!" << std::endl; } > > int main(int argc, char** argv) > { > std::set_terminate(unhandled_exception_handler); > > //rest of your program. > } > > Then put a breakpoint inside unhandled_exception_handler and > when it gets hit walk up the callstack in the debugger to see > where the exception is occuring. In addition you can > determine the thread id again using the same method you used > in the first step. My guess is that they're not in the same > thread. I'm not sure if it applies to your scenario, but > remember that the operation's completion handler is invoked > on is not necessarily the same thread that the request is > issued on depending on how you're using the io_service > object. So while you have a try {} catch(...) {} in the > completion handler, if the exception is on the other thread > that does you no good. > Thanks for the tip, I didn't know about set_terminate, I made that change. I put a breakpoint in my terminate handler, and the callstack looks like: 32 unhandled_exception_handler() /home/noirs/workspace/myfile.cpp:35 0x0000000000438764 31 <symbol is not available> 0x00007f9ceb0d04b6 30 <symbol is not available> 0x00007f9ceb0cf6ab 29 __gxx_personality_v0() 0x00007f9ceb0d0278 28 <symbol is not available> 0x00007f9ceab7cff3 27 _Unwind_Resume() 0x00007f9ceab7d0b8 26 ~ProtoBufStreamAdaptor() /home/noirs/workspace/myfile2.cpp:10 0x000000000042c6e5 25 CWebServer::HandleGetNeighbors() /home/noirs/workspace/myfile3.cpp:215 0x000000000041d2d8 24 CWebServer::OnHttpRequest() /home/noirs/workspace/myfile3.cpp:89 0x000000000041e790 23 CBaseWebServer::HandleHTTPRequest() /home/noirs/workspace/myfile4.cpp:92 0x00000000004092ef 22 CBaseWebServer::HandleAccept() /home/noirs/workspace/myfile4.cpp:61 0x0000000000409a9e HandleAccept looks like: void CBaseWebServer::HandleAccept(shared_ptr<tcp::socket> pSocket, const boost::system::error_code& error) { if ( !error ) { try { HandleHTTPRequest(pSocket); StartAccept(); } catch ( ... ) { cout << "Unhandled exception in HandleAccept"; } } else { cout << "HandleAccept received error: " << error.message().c_str() << endl; } }

2 1