October 2013 - Boost-users - lists.boost.org

[Asio] Example of the "passing the buck" pattern
by Sorin Fetche 28 Oct '13

28 Oct '13

Hi all, Although the pattern of "passing the buck" has been mentioned in several places in the context of Boost.Asio, I didn't find any self-contained example that demonstrates it in a reusable manner. So, after going through all the information I could find, I tried to create such an example that demonstrates it using C++03.I would like to ask for feedback related to the attached sample code (its "Test Infrastructure" and "Test Code" sections) and double check that it does indeed depict what "passing the buck" means. For future reference I'm listing here the all the sources of information I could find related to the pattern of "passing the buck". it also turned out that a helper utility is needed in order to wrap boost::bind created handlers and have the wrapper integrate with the Asio customization points. - N3388 paper: Using Asio with C++11 http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3388.pdf Chapter 7 describes this strategy to develop efficient and generic composed operations by letting their caller decide via the provided completion handler how the intermediary handlers should interact with the Asio customization points. - Thinking Asynchronously: Designing Applications with Boost.Asio https://github.com/boostcon/2011_presentations/raw/master/mon/thinking_asyn… The "Managing Complexity" chapter references the "pass the buck" strategy with slides 113 and 114 showing invocation and allocation hooks that call the hooks of a nested handler. - The implementation of higher level functions from Boost.Asio like async_read or async_write. The problem with them being an example of the pattern is that they are using custom classes for the intermediary operation handlers instead of relying on boost::bind to build them on the fly. - Asio Samples project http://sourceforge.net/projects/asio-samples For example its handler wrapper: context_alloc_handler and its usage in the echo server implementation. Thank you, Sorin Fetche

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Preprocessor Recursion
by Mitch Besser 27 Oct '13

27 Oct '13

I'm trying to create a 'C' macro that will define and initialize static data. For example: STATIC_CONST_STRUCT ( A, a, MEMBER_DATA(CONST_STR, a, "Hello, a") MEMBER_DATA(CONST_STR, b, "Hello, b") MEMBER_STRUCT ( C, c, MEMBER_DATA(CONST_STR, d, "Hello, d") MEMBER_DATA(CONST_INT, e, 1) ) ); Would cause the 'C' preprocessor to create: static const struct A { CONST_STR a; CONST_STR b; struct C { CONST_STR d; CONST_INT e; } c; } = {"Hello, a", "Hello, b", {"Hello, d", 1}}; If I could use C++, this would be easy, but I'm using 'C' and it would be very helpful to have the initialization along with the declaration. I can't quite figure out how to make this work. My macros stop expanding. I suspect the recursive nature of the problem having an arbitrarily deep nesting is why. If it helps, I do have a maximum depth for the nesting. I've tried reading the docs and learn more about recursion, but I can't seem to find a solution. I suspect I'm close. Here's what I have so far (not claiming this is a good solution, so feel free to suggest anything that would make this better): #define MEMBER_DATA_TAG 0 #define MEMBER_STRUCT_TAG 1 #define MEMBER_TAG(MEMBER) BOOST_PP_SEQ_ELEM(0, MEMBER) #define MEMBER_DATA_TYPE(MEMBER_DATA) BOOST_PP_SEQ_ELEM(1, MEMBER_DATA) #define MEMBER_DATA_NAME(MEMBER_DATA) BOOST_PP_SEQ_ELEM(2, MEMBER_DATA) #define MEMBER_DATA_VALUE(MEMBER_DATA) BOOST_PP_SEQ_ELEM(3, MEMBER_DATA) #define MEMBER_STRUCT_TYPE(MEMBER_STRUCT) BOOST_PP_SEQ_ELEM(1, MEMBER_STRUCT) #define MEMBER_STRUCT_NAME(MEMBER_STRUCT) BOOST_PP_SEQ_ELEM(2, MEMBER_STRUCT) #define MEMBER_STRUCT_MEMBER_SEQ(MEMBER_STRUCT) BOOST_PP_SEQ_ELEM(3, MEMBER_STRUCT) #define MEMBER_DATA(TYPE, NAME, VALUE) ((MEMBER_DATA_TAG)(TYPE)(NAME)(VALUE)) #define MEMBER_STRUCT(TYPE, NAME, MEMBER_SEQ) ((MEMBER_STRUCT_TAG)(TYPE)(NAME)(MEMBER_SEQ)) #define IS_MEMBER_STRUCT(MEMBER_SEQ_ELEM) BOOST_PP_EQUAL(MEMBER_TAG(MEMBER_SEQ_ELEM), MEMBER_STRUCT_TAG) #define MEMBER_STRUCT_DECLARE(TYPE, NAME, MEMBER_SEQ) \ struct TYPE \ { \ BOOST_PP_SEQ_FOR_EACH(MEMBER_ELEM_DECLARE, BOOST_PP_EMPTY(), MEMBER_SEQ) \ } NAME #define MEMBER_ELEM_DECLARE(_r, _data, MEMBER_SEQ_ELEM) \ BOOST_PP_IIF \ ( \ IS_MEMBER_STRUCT(MEMBER_SEQ_ELEM), \ MEMBER_STRUCT_DECLARE \ ( \ MEMBER_STRUCT_TYPE(MEMBER_SEQ_ELEM), \ MEMBER_STRUCT_NAME(MEMBER_SEQ_ELEM), \ MEMBER_STRUCT_MEMBER_SEQ(MEMBER_SEQ_ELEM) \ ), \ MEMBER_DATA_DECLARE \ ( \ MEMBER_DATA_TYPE(MEMBER_SEQ_ELEM), \ MEMBER_DATA_NAME(MEMBER_SEQ_ELEM), \ MEMBER_DATA_VALUE(MEMBER_SEQ_ELEM) \ ) \ ); #define MEMBER_DATA_DECLARE(TYPE, NAME, VALUE) TYPE NAME #define MEMBER_VALUE_INIT(MEMBER_SEQ) \ BOOST_PP_SEQ_FOR_EACH_I(MEMBER_VALUE_INIT_DECLARE, BOOST_PP_EMPTY(), MEMBER_SEQ); #define MEMBER_VALUE_INIT_DECLARE(_r, _data, i, MEMBER_SEQ_ELEM) \ BOOST_PP_COMMA_IF(i) \ BOOST_PP_IIF \ ( \ IS_MEMBER_STRUCT(MEMBER_SEQ_ELEM), \ {MEMBER_VALUE_INIT(MEMBER_SEQ_ELEM)}, \ MEMBER_DATA_VALUE(MEMBER_SEQ_ELEM) \ ) #define STATIC_CONST_STRUCT(TYPE, NAME, MEMBER_SEQ) \ static const MEMBER_STRUCT_DECLARE(TYPE, NAME, MEMBER_SEQ) = \ { \ MEMBER_VALUE_INIT(MEMBER_SEQ) \ } Thanks. -- "лось и белка"

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[geometry] Difference problem using boost geometry in 1.47
by Macumber, Daniel 26 Oct '13

26 Oct '13

I am using boost geometry in 1.47 and am pretty happy with it. However, I am having a problem performing an intersection that I can't figure out how to solve. When I difference two geometries, I am sometimes left with a result that uses reverse winding to subtract a piece of the result rather than providing a "clean" polygon with winding in one direction only. I've posted an image here that demonstrates this: http://oi42.tinypic.com/2elfp0o.jpg I get the feeling that if I were to use the right models this might somehow be fixed? If not is there an algorithm that can clean up the result? Here is the code I am using: typedef boost::geometry::model::d2::point_xy<double> BoostPoint; typedef boost::geometry::model::polygon<BoostPoint> BoostPolygon; typedef boost::geometry::model::ring<BoostPoint> BoostRing; BoostRing facePolygon; BoostRing otherFacePolygon; std::vector<BoostPolygon> faceDifferenceResult; .... boost::geometry::difference(facePolygon, otherFacePolygon, faceDifferenceResult); Any ideas are much appreciated, thanks a lot, Dan

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MFC ASSERT in dllinit.cpp line 703 when using Boost.Log
by Simon Martin 25 Oct '13

25 Oct '13

Hi, I receive an assertion, when I try to use Boost.Log in one of my DLLs. I have a tools.dll, which contains my logging facility and I tried to implement to logging stuff with Boost.Log. This tools.dll is referenced by another helper.dll and both DLLs are used in the application. However, when I start the application, I get the famous ASSERT. This happens with Boost 1.54 and Boost.Log as well as with Boost 1.48 and Boost.Log 1.1. I've digged through lots of mailing lists and old postings today. What I understood so far, there's an issue with _pRawDllMain pointer in Boost.Thread, some suggested commenting it out in #include <boost/thread/detail/tss_hooks.hpp>, but this leads to memory leaks? This thread http://lists.boost.org/threads-devel/2009/06/0476.php said it would be fixed after 1.40, but I don't know, if this has been done. Dynamic linking to Boost as suggested here http://stackoverflow.com/questions/5355931/adding-include-boost-thread-mute… did not help. Any hints, what I should check? Thanks Simon

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Reading & Parsing an .ini input file using BOOST... ..!!
by Rahul Mathur 25 Oct '13

25 Oct '13

All, Need small help. I have an "input.ini" input file which contains sample values like – --- App=| 5000 | 5001 | 0 | | | | 1BYTE | --- Starting with word (viz. App), followed by equal sign, than data within pipes (|) and blank space between two pipes ( | | ). Anything only between two pipes is to be read. I am looking to parse this input file. After parsing, assign each data to struct member type and than send this complete struct as socket. I am looking to use Boost property tree (or the needed one) and finally the ASIO to send the complete filled struct as stream. I tried below code to read complete data and it worked but - --- #include <iostream> #include <boost/property_tree/ptree.hpp> #include <boost/property_tree/ini_parser.hpp> #include <boost/filesystem/fstream.hpp> int main() { boost::property_tree::ptree pt; boost::property_tree::ini_parser::read_ini("input.ini", pt); std::cout << pt.get<std::string>("App") << std::endl; } --- But, how to read between pipes? Any clue?

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BOOST_INTERLOCKED_INCREMENT
by gast128 24 Oct '13

24 Oct '13

Hello all, we use these macro's to be more portable, but are these 'official' Boost functionality? they are defined in <boost/detail/interlocked.hpp> which made me doubt. Ofc better to use atomics in future, bit no time for that right now.

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[1.55.0] Beta 1 Available
by Marshall Clow 24 Oct '13

24 Oct '13

Boost release 1.55.0 beta 1 is now available from SourceForge See http://sourceforge.net/projects/boost/files/boost/1.55.0.beta.1/ This release contains 1 new library: * Predef: This library defines a set of compiler, architecture, operating system, library, and other version numbers from the information it can gather of C, C++, Objective C, and Objective C++ predefined macros or those defined in generally available headers, from Rene Rivera. For details of what's in the release, see http://www.boost.org/users/history/version_1_55_0.html. Note that the links to files on this web page are for the final release - use the SourceForge link above to get the beta files. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team

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boost.org/users/license.html page out of date and misleading?
by John DiMatteo 23 Oct '13

23 Oct '13

http://www.boost.org/users/license.html says "Currently, some Boost libraries have their own licenses." Is this correct in stating that some Boost libraries don't use the Boost Software License? If so, what is an example of a Boost library that does not use the Boost Software License? Is there a definitive list of which libraries don't use the Boost Software License? I discussed this on the #boost irc channel today, and it was suggested that the license.html page is out of date, and that all of the Boost libraries have already been updated to use the Boost Software License. If this is indeed the case, can we please update the license.html page? Thanks

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error compiling boost svn repo
by Freddy Martinez Garcia 23 Oct '13

23 Oct '13

hi to everybody... I have downloaded the boost svn repo and I'm trying to compile it, but I've the following error: gcc.compile.c++ bin.v2/libs/iostreams/build/gcc-4.8/release/threading-multi/bzip2.o libs/iostreams/src/bzip2.cpp:20:56: fatal error: bzlib.h: No such file or directory #include "bzlib.h" // Julian Seward's "bzip.h" header. ^ compilation terminated. "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pthread -fPIC -DBOOST_ALL_NO_LIB=1 -DBOOST_IOSTREAMS_DYN_LINK=1 -DBOOST_IOSTREAMS_USE_DEPRECATED -DNDEBUG -I"." -c -o "bin.v2/libs/iostreams/build/gcc-4.8/release/threading-multi/bzip2.o" "libs/iostreams/src/bzip2.cpp" ...failed gcc.compile.c++ bin.v2/libs/iostreams/build/gcc-4.8/release/threading-multi/bzip2.o... ...skipped <pbin.v2/libs/iostreams/build/gcc-4.8/release/threading-multi>libboost_iostreams.so.1.55.0 for lack of <pbin.v2/libs/iostreams/build/gcc-4.8/release/threading-multi>bzip2.o... ...skipped <pstage/lib>libboost_iostreams.so.1.55.0 for lack of <pbin.v2/libs/iostreams/build/gcc-4.8/release/threading-multi>libboost_iostreams.so.1.55.0... ...skipped <pstage/lib>libboost_iostreams.so for lack of <pstage/lib>libboost_iostreams.so.1.55.0... gcc.compile.c++ bin.v2/libs/iostreams/build/gcc-4.8/release/link-static/threading-multi/bzip2.o libs/iostreams/src/bzip2.cpp:20:56: fatal error: bzlib.h: No such file or directory #include "bzlib.h" // Julian Seward's "bzip.h" header. ^ compilation terminated. "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pthread -DBOOST_ALL_NO_LIB=1 -DBOOST_IOSTREAMS_USE_DEPRECATED -DNDEBUG -I"." -c -o "bin.v2/libs/iostreams/build/gcc-4.8/release/link-static/threading-multi/bzip2.o" "libs/iostreams/src/bzip2.cpp" ...failed gcc.compile.c++ bin.v2/libs/iostreams/build/gcc-4.8/release/link-static/threading-multi/bzip2.o... ...skipped <pbin.v2/libs/iostreams/build/gcc-4.8/release/link-static/threading-multi>libboost_iostreams.a(clean) for lack of <pbin.v2/libs/iostreams/build/gcc-4.8/release/link-static/threading-multi>bzip2.o... ...skipped <pbin.v2/libs/iostreams/build/gcc-4.8/release/link-static/threading-multi>libboost_iostreams.a for lack of <pbin.v2/libs/iostreams/build/gcc-4.8/release/link-static/threading-multi>bzip2.o... ...skipped <pstage/lib>libboost_iostreams.a for lack of <pbin.v2/libs/iostreams/build/gcc-4.8/release/link-static/threading-multi>libboost_iostreams.a... ...failed updating 2 targets... ...skipped 6 targets... I'm using ubuntu 13.10... somebody know what i'm i suppose to do ?? best regards Freddy -- ------- "El tamaño de tus logros depende del tamalo de tus metas." ------- Freddy Martinez Garcia Lic. en Ciencia de la Computación. Edad: 31 Años Nacido en: Santiago de Cuba Recide en: Buenos Aires. Capital Federal e-mails: * freddy311082(a)gmail.com * freddymg311082(a)hotmail.com

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Mixing signals2 and asio mechanism failing
by ustulation 22 Oct '13

22 Oct '13

I've the following: <1> a single instance of io_service object with a program life-time and several threads calling it's run() method. io_service::work is given to it so that it never terminates (unless we stop it). <2> class A which has boost::signals2::signal connecting functions for callback. * async operations (eg., async_read_until, async_write etc) <3> class B which is derived from std::shared_from_this ; * has a composition of class A as std::unique_ptr which is instantiated in B's constructor ; <c> has functions/listeners which are registered with signals of class A (eg., signals2::connection connectionObj = uniqPtrA->someSig.connect([=]{shared_from_this_ptrB->listenerFuncOfB();}); <4> Another thread outside the thread-pool of <1> above which instantiates (and manages) class B: auto ptrB = std::make_shared(); //and further operations. The problem is when I need to destroy ptrB I can't. For instance, i call some method of class B on ptrB to clear all connections it has with class A and allow ptrB to go out of scope, but class B destructor is never called: {//local scope auto ptrB = std::make_shared(); ptrB->connectListenersToA(); /* eg auto self = shared_from_this(); connectionObj = uniqPtrA->someSig.connect([=]{self ->listenerFuncOfB();}); referring to <3> above */ //... do some operations ptrB->disconnectListenersWithA(); //eg connectionObj.disconnect(); referring to <3> above }//Scope ends I want ptrB to destroy the underlying pointer. The ptrB destructor is never called because signals2::connection::disconnect does not seem to wipe out the given slot so the shared_ptr reference of B remains with the signal in class A as anonymous functor (due to lambda in <3> above) containing it does not get destroyed. How do I achieve this? -- View this message in context: http://boost.2283326.n4.nabble.com/Mixing-signals2-and-asio-mechanism-faili… Sent from the Boost - Users mailing list archive at Nabble.com.

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