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Re: [Boost-users] [date_time][serialization] Fast persistence ofboost::date_time::ptime
by pete＠pcbartlett.com 28 Jan '10

28 Jan '10

On Thu 28/01/10 13:20 , Jeff Garland <azswdude(a)gmail.com> wrote: > Igor R wrote: > >> However on this glance this doesn’t seem possible > non-intrusively. Perhaps > >> I’ve missed something, perhaps there’s a third way > – I would be grateful if > >> any could share any ideas. > > > > Yes, it was already discussed here: > > > http://groups.google.com/group/boost-list/browse_thread/thread/d799ca831185 > 01e4/04b184b4c7af8c0b?show_docid=04b184b4c7af8c0b> > > I believe nothing changed since then. > There's not a direct way to get at the internal representation of a > ptime, > which varies based on how the library is compiled (64 or 96 bits > depending on > settings -- the thread above isn't completely accurate on this > point). If > it's critically important, of course, you could modify the source > directly to > fit your particular setup and provide the internal representation > for your app > to serialize (add a to_int64 for example). As a general rule, > however, it's > unwise to store these values as integers since future versions of > the library > might, for example, expand the epoch range and hence these > serialized values > wouldn't be compatible -- that, and the aforementioned fact that the > internal > size isn't fixed are a couple of the reasons there isn't direct > access. > Jeff Thank you both for your helpful replies (and for the helpful library!) They are good reasons. The Boost.Serialization library has it versioning mechanisms so it would be possible for a more intrusive set of load/save functions to be future- and config-proof as well as being fast. However whilst that would suit me, it has its costs - I am sure many like the readability of the current archives and I am sure the maintainer likes that the serialization functions only need to use public members of the date_time classes!

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bjam --address-model=64 doesn't work anymore?
by Daher 28 Jan '10

28 Jan '10

Using msvc100 building with: bjam --address-model=64 and unable to link output libs in my project. msvc saying its X86 and not X64 am i missing something?

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C++ and quality of software
by Peter Foelsche 28 Jan '10

28 Jan '10

I was thinking. There should be some C++ software quality assurance institution. They would give a stamp of approval to software written in C++. Criteria would be: a.. no usage fixed-sized buffers b.. no usage of functions from the c library, which do not check for correct type, like *printf(), *scanf(). c.. no dangling resources, no resource leaks in any case d.. usage of C++ Exception Handling for reporting errors (all fallible OS-calls are wrapped into C++, this can be checked by denying read/write permissions on some object, the software is trying to read/write to) e.. clean design -- e.g. no protocols (no protocols is my way of saying, that all methods of classes can be used and make sense to be used, as soon as this object exists) What do you think? I also published this on my blog: http://foelsche.spaces.live.com/blog/cns!2BFA22F3AB9E833!921.entry

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[date_time][serialization] Fast persistence of boost::date_time::ptime
by Pete Bartlett 28 Jan '10

28 Jan '10

I am interested in serializing data structures like vector< pair< boost::date_time::ptime , double> > as quickly as possible. I see that ptime is a serializable object (in the Boost.Serialization sense) but on the surface this implementation looks slow - we first get a date and time_duration and then serialize the various components (mins,secs,subsecs) separately for the latter and construct a full ISO string for the date. Something faster is surely possible - digging into the implementation it looks like a (non-special) ptime is represented as boost::uint64_t so if we were privy to all implementation details we could use serialize that. However on this glance this doesn't seem possible non-intrusively. Perhaps I've missed something, perhaps there's a third way - I would be grateful if any could share any ideas. Thanks, Pete

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passing socket descriptor to a function
by pedro chaparro 28 Jan '10

28 Jan '10

Hi, i have the code below, i want to separate the open socket code from the writting fucntions, i want to call a escribir() function from the main but i¡m not clear the value i have to pass the function, inthe way i have below it has not work. thanks #include <ctime> #include <iostream> #include <string> #include <boost/asio.hpp> using boost::asio::ip::tcp; void escribir( tcp::socket socket){ std::string message = "mensaje"; boost::system::error_code ignored_error; boost::asio::write(socket, boost::asio::buffer(message), boost::asio::transfer_all(), ignored_error); } int main() { int contador=0; try { boost::asio::io_service io_service; tcp::acceptor acceptor(io_service, tcp::endpoint(tcp::v4(), 5544)); for (;;) { tcp::socket socket(io_service); acceptor.accept(socket); escribir(socket); } } catch (std::exception& e) { std::cerr << e.what() << std::endl; } return 0; } -- Ing Pedro Alonso Chaparro Valero Ciudad Politecnica de la Innovación iTEAM - Mobile Communications Group Polytechnic University of Valencia C\ Camino de Vera S/N, Edificio 8G 46022 Valencia, Spain

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Re: [Boost-users] [interprocess] shared_memory_object constructor with create_only parameter
by Philipp Hamann 28 Jan '10

28 Jan '10

Hi all, I am sorry. I made a mistake. My first problem is solved. It is not a bug. > I have some problems using the shared_memory_object constructor with the > create_only parameter. > The goal is to allow only one process to write to the shared memory. So > I create a shared_memory_object with the create_only parameter. For the > first process this is successful (as I assumed), but for the second > process (same parameters) this is successful, too (not as I assumed). > The documentation of boost says that it should throw an exception, if > the shared memory is allready created. Is this a bug or a misuse or > understanding of the library? But the second problem concerning shared_memory_object::remove(const char* name) is still present. > I realized another problem. If I call the static function > shared_memory_object::remove(const char* name), the memory should be > removed only when no further process has access to the memory. This > seems also not to work. I did the following: > 1. create shared memory for writing. > 2. open shared memory for reading > 3. shared_memory_object::remove(const char* name) (from the reading > process) > 4. reopen the shared memory for reading -> exception: can not find the file Thanks for your help and apoligizes for bothering you with my first problem. Philipp

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serialization: pointer reconstruction
by Noah Roberts 27 Jan '10

27 Jan '10

A while back I asked about saving a pointer to an item in another class that is stored as a direct instance variable (no pointer). Here's a brief illustration: struct A { }; struct B { A a; }; struct C { A * a; // points to a B::a. }; I have an idea how to store and restore these relationships but I'd like to see if there are any improvement ideas and/or direction to existing behavior I'm not seeing in the documentation. My idea is to first store B::a (which simply makes sense in my problem anyway) and when I do this to call some custom support functions to generate a unique ID for the object at that address and store it first, then the rest of the data in A. This would appear in A::serialize and the unique ID would be stored in the Archive (added behavior) as a map from address to uid. Then when storing C I would request the unique ID for the address the pointer stores and store it. On reading I read B::a first and it sort of reverses the process. The uid is read and then A::serialize stores the uid and 'this' in the archive map in a uid->address format. I then read the uid on reading C::a and request the address from the archive using that value. I've already subclassed the Archive in order to pass around other load information needed by classes that didn't have local copies, so that's the easy part (though it wasn't a straight forward operation). The question I have though is that since the pointer archiving already must use some similar type of API, can I use it instead of rolling my own and how would I do that?

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Issues with unnamed enums
by Kyle Altendorf 27 Jan '10

27 Jan '10

I have just tried to use Boost for the first time and it appears to not take kindly to unnamed enums from another library I use and (once those were named) some Microsoft SDK. I am using: Windows XP SP3 Visual Studio 2008 SP1 Boost 1.41.0 More specifically, after adding '#include <boost/foreach.hpp>' I started getting compilation errors such as: 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : error C2332: 'class' : missing tag name 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : error C2011: '<unnamed-tag>' : 'enum' type redefinition 1> c:\korvis\korvislibs\khmilib\kvdisplay.h(18) : see declaration of '<unnamed-tag>' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : error C2143: syntax error : missing ',' before 'constant' kvdisplay.h(18) is the definition of an unnamed enum in another library I use. iterator_facade.hpp(43) is (including comments before it): > // This forward declaration is required for the friend declaration > // in iterator_core_access > template <class I, class V, class TC, class R, class D> class iterator_facade; I went through and named a each of the unnamed enums as the compiler referenced them until I got to an issue with shlwapi.h from a Microsoft SDK. Here's the complete compiler error list at that point: 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : error C2332: 'class' : missing tag name 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : error C2011: '<unnamed-tag>' : 'enum' type redefinition 1> c:\program files\microsoft sdks\windows\v6.0a\include\shlwapi.h(1550) : see declaration of '<unnamed-tag>' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : error C2143: syntax error : missing ',' before 'constant' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(479) : error C2332: 'class' : missing tag name 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(479) : error C2011: '<unnamed-tag>' : 'enum' type redefinition 1> c:\program files\microsoft sdks\windows\v6.0a\include\shlwapi.h(1550) : see declaration of '<unnamed-tag>' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(479) : error C2143: syntax error : missing ',' before 'constant' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(484) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(484) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(485) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(485) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(487) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(487) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(488) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(488) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(489) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(489) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(490) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(490) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(494) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(494) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(501) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(508) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(43) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(566) : error C2332: 'class' : missing tag name 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(566) : error C2011: '<unnamed-tag>' : 'enum' type redefinition 1> c:\program files\microsoft sdks\windows\v6.0a\include\shlwapi.h(1550) : see declaration of '<unnamed-tag>' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(566) : error C2143: syntax error : missing ',' before 'constant' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(567) : error C2988: unrecognizable template declaration/definition 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(567) : error C2059: syntax error : 'constant' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(567) : error C2065: 'V' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(567) : error C2065: 'TC' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(567) : error C2065: 'R' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(567) : error C2065: 'D' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(572) : error C2332: 'class' : missing tag name 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(572) : error C2011: '<unnamed-tag>' : 'enum' type redefinition 1> c:\program files\microsoft sdks\windows\v6.0a\include\shlwapi.h(1550) : see declaration of '<unnamed-tag>' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(573) : error C2065: 'V' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(573) : error C2065: 'TC' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(573) : error C2065: 'R' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(573) : error C2065: 'D' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(574) : error C2334: unexpected token(s) preceding '{'; skipping apparent function body 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(721) : error C3855: 'boost::iterator_facade': template parameter '__formal' is incompatible with the declaration 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(721) : error C2977: 'boost::iterator_facade' : too many template arguments 1> c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(601) : see declaration of 'boost::iterator_facade' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(724) : error C2332: 'class' : missing tag name 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(724) : error C2011: '<unnamed-tag>' : 'enum' type redefinition 1> c:\program files\microsoft sdks\windows\v6.0a\include\shlwapi.h(1550) : see declaration of '<unnamed-tag>' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(724) : error C2143: syntax error : missing ',' before 'constant' 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(725) : error C2065: 'V' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(725) : error C2065: 'R' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(725) : error C2065: 'TC' : undeclared identifier 1>c:\korvis\boost\include\boost\iterator\iterator_facade.hpp(726) : fatal error C1903: unable to recover from previous error(s); stopping compilation Am I correct that the unnamed enums are somehow causing the problem? Any help you can offer understanding or resolving this issue would be greatly appreciated. Thanks for your time, -kyle

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Query re connected components in the Boost Graph Library
by Christopher Henrich 27 Jan '10

27 Jan '10

The connected_components function in the BGL returns the connected component information in a "ComponentMap," in which the value for node i is the number c[i] of the component containing that node. Is the sequence of component numbers "restricted growth" ? That is, can I assume that c[0] = 0 and for i > 0, c[i] <= 1 + max(c[0], ..., c[i-1])? It would appear that this would be true, as a consequence of the easiest way to use depth-first search to find the components. And a brief attempt to read the source code encourages me to believe it. But I may not have understood the source code. And I do not find it stated in the boost documentation, nor in /The Boost Graph Library/. Thanks in advance for clarification on this point. Christopher Henrich chenrich(a)monmouth.com mathinteract.com

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[thread] Is a call to interrupt_all blocking?
by Sachin Garg 27 Jan '10

27 Jan '10

Does a call to interrupt_all blocks the calling thread, waiting for all threads to be interrupted? Or is it supposed to return immediately and let the threads hit their interruption points later? I have a thread_group and I want to call interrupt_all to stop all threads in the group from 'within' one of the threads in that group. This would be possible only if interrupt_all in not blocking, otherwise I will need to somehow signal some other thread to do the interrupt_all on that group. SG

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