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

Is Source available?
by Billy Ng 29 May '12

29 May '12

Is Source avaialble as I cannot see it in the download page or SVN? If yes, how can I access to do? BNG

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[ASIO]: Best solution for Publisher/Subscriber pattern
by Ingo Maindorfer 28 May '12

28 May '12

Hi All, currently we do some research in how we can do implement the classical Publisher/Subscriber pattern using ASIO. We had one thread that produces some kind of a message and like to send it out to 1 to n subscribers via TCP, where n is < 5. Message rate will be up to 800 Hz. My first idea is that the producer thread puts the message in a blocking queue. On the other end a consumer thread waits, takes the message and send it to the subscribers via synchronous or asynchronous send. One requirement is, when one connection blocks (because their client is buggy/hangs) it's ok to drop messages for that connection, but we should deliver to the other subscribers. It's also a one way communication from publisher to subscriber. Can someone provide some hints for best practices / design patterns / comments please? If I show up with some other lib like ZeroMQ my colleagues will fry me, so it's the easiest to use boost also for that task.. Best, Ingo

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documentation typo
by John M. Dlugosz 28 May '12

28 May '12

I noticed: “ trait is_convertible in the C==0x standard.” where == should be ++ in libs/utility/doc/html/declval.html Is anyone around who can simply fix that typo? —John

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"invalid signature" in boost::archive::binary_iarchive
by Ibrahim Beicker 28 May '12

28 May '12

I had to port a multi-process application to 64 bits and I rely on boost serialization to send messages, that are maps of key-values, into Microsoft queues to the other modules. It works just fine into 32 bits but when I run it in 64 the constructor throws an "invalid signature" exception void Message::fromBinary( const std::string& data ) { std::stringstream ss; ss << data; boost::archive::binary_iarchive ia(ss); //exception here ia >> *this; } I managed to debug into basic_binary_iarchive.ipp and this 'if' @ line 72 fails if(file_signature != BOOST_ARCHIVE_SIGNATURE()) boost::serialization::throw_exception(archive_exception(archive_exception::invalid_signature)); inside this file I have no debug symbols so I don't know the values of 'file_signature' and 'BOOST_ARCHIVE_SIGNATURE' or where BOOST_ARCHIVE_SIGNATURE is defined. Some additional information: the modules are all running on the same machine, on windows 7 64-bits, and compiled by visual studio 2010 x64 including static boost libraries 1.45. What causes this and how can I fix it?

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[asio] Using asio for asynchronous event processing
by Edward Diener 28 May '12

28 May '12

I do not understand the documentation for asio, or even if it pertains to the programming problem I am trying to solve. The doc, for whatever reason, is poor regarding practical use. But rather than complain about the doc I will ask a specific problem related to what I am trying to do and hopefully someone can help me or point me to something in the doc by which I can understand how to use asio for my problem. I need to design generalized asynchronous events triggered by an event source and handled by an event handler. The event source would trigger an event declared as a callable object, as in boost::function, and an event handler would eventually handle the event asynchronously. The event source and the event handler would be in different threads of an application but not in different applications. The event source triggers the event but does not block in any way waiting for the event to be processed. The event source may subsequently trigger other asynchronous events to be eventually handled in the same way without blocking. The event handler is able to check for events periodically from within its own thread. Each event itself could be a totally different callable object, but the event source and the event handler both know the callable prototype for any given event. The event source and the event handler are completely disconnected in that neither knows about the other. For any given asynchronous event there may be any number of event handlers when an event is triggered. Can I use asio to implement such a solution ? The doc suggests that asio does not only deal in i/o events, such as networking and sockets, but I could not understand whether it deals in generalized asynchronous operations or not. The proactor pattern is understandable but there appears to be nothing in the doc which connects the elements of the proactor pattern to classes in asio. The basic tutorial as well as the sockets tutorial does not enlighten me at all. Hopefully someone here can help.

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Asynchronous signals library
by Edward Diener 28 May '12

28 May '12

The signals and signals2 library work with signals ( events ) which are handled synchronously. Is there any Boost library, based on the function prototyping methods of signals(2), in which the signals are handled asynchronously ?

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BOOST_ALL_NO_LIB / BOOST_THREAD_NO_LIB / BOOST_THREAD_DYN_LINK etc etc etc
by Josh Quigley 28 May '12

28 May '12

Hi, I'm trying to link to Boost.Thread DLL's. If I define BOOST_ALL_NO_LIB everything works fine - but it wants to link all packages as DLL, instead of just Boost.Thread. None of the following cause dynamic linking - that is I get a linker error saying the static *.lib could not be found. (defined on the command line, Visual Studio 2010) BOOST_THREAD_NO_LIB BOOST_THREAD_DYN_LINK BOOST_THREAD_ALL_DYN_LINK BOOST_THREAD_BUILD_DLL BOOST_THREAD_USE_DLL Is there a problem with - what I'm doing; - Visual Studio 2010; or - boost.thread? Cheers, Josh.

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arm-elf-gcc 4.0.1 class alignment
by Pierre-Andre van Leeuwen 28 May '12

28 May '12

Hi Not sure if this belongs on this list or the Boost.Build list, but the problem exists when using Boost as well as building it. I'm using Boost with the ARM-ELF-GCC toolchain with gcc version 4.0.1. When building the Boost serialization library, I get the following error: ./boost/archive/basic_binary_oarchive.hpp:80: error: invalid application of 'sizeof' to incomplete type 'boost::STATIC_ASSERTION_FAILURE<false>' It turns out that sizeof(class_id_type ) == 4 in stead of 2, where class_id_type is defined as follows: class class_id_type { private: typedef int_least16_t base_type; base_type t; ... }; Using a toolchain with a more recent gcc version (arm-none-eabi-gcc 4.4.1) works correctly, but unfortunately I need to get Boost working with the old toolchain as well. I have tried to add __attribute__ ((packed)) to the class declaration, but that breaks as well (cannot bind packed field in operator int_least16_t). Is there anything I can do to rectify the situation? My user-config.jam contains the following: using gcc : armelf : "arm-elf-gcc.exe" : <cflags>-nostdlib <cxxflags>-DBOOST_NO_INTRINSIC_WCHAR_T <cxxflags>-D__OAT_API_VERSION__=637 <cxxflags>-D__WIP_PLUGIN_VERSION__=543 <cxxflags>-D__arm <cxxflags>-D_LITTLE_ENDIAN <cxxflags>-IC:\Program Files (x86)\Sierra Wireless\Embedded Software\com.wavecom.openat.ide.spm.lib.os.model.6.37.0.201202060950_6.37.0.201202060950\resources/ADL/itf <cxxflags>-IC:\Program Files (x86)\Sierra Wireless\Embedded Software\com.wavecom.openat.ide.spm.lib.os.model.6.37.0.201202060950_6.37.0.201202060950\resources/ADL/basic <cxxflags>-IC:\Program Files (x86)\Sierra Wireless\Embedded Software\com.wavecom.openat.ide.spm.lib.plugin.model.WIP.5.43.0.201202100610_5.43.0.201202100610\resources/WIP/itf <cxxflags>-fshort-enums <cxxflags>-fdollars-in-identifiers <cxxflags>-nostartfiles <cxxflags>-fno-strict-aliasing <cxxflags>-fno-common <cxxflags>-fomit-frame-pointer <cxxflags>-mthumb-interwork <cxxflags>-mthumb <cxxflags>-march=armv5te <cxxflags>-msoft-float <cxxflags>-mfpu=fpa <cxxflags>-mapcs <cxxflags>-mno-apcs-stack-check <cxxflags>-mlittle-endian <architecture>arm <address-model>32 ; I'm building boost with the following command .\b2 variant=debug,release link=static threading=single toolset=gcc-armelf --debug-configuration --debug-building --with-serialization stage Any help will be appreciated. Pierre-Andre van Leeuwen Director | Gendac (Pty) Ltd<http://www.gendac.com/>

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mpl and fusion containers: numbered vs variadic
by MM 27 May '12

27 May '12

Hello, Is it true that as a general rule, using the numbered version instead of the variadic version yields faster compile times? Or is it just about compilers supporting variadic templates? MM

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BOOST_RESULT_OF_USE_DECLTYPE and Boost.Optional ?
by John M. Dlugosz 27 May '12

27 May '12

I turned on BOOST_RESULT_OF_USE_DECLTYPE and used boost::result_of because the std::tr1::result_of that comes with VS10 doesn't use declspec at all and thus doesn't work right with lambda functions. This passes my unit tests, but fails on a piece of code that has a function returning an instantiation of boost::optional. It seems confused as to whether the value held in the optional is as-specified or has a reference added to it. I wonder if this is a specific issue with optional that might be addressed/worked-around/patched, or perhaps there is a way to enable declspec-based testing just for the code that wanted it and not globally? —John

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