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[statechart] Events forwarding and orthogonal states
by lucaghera 13 Aug '15

13 Aug '15

Hi all, I've a problem similar to the one discussed in this old post: http://boost.2283326.n4.nabble.com/statechart-Broadcasting-events-to-orthog… I have a state, let's call it A, which contains two orthogonal regions. State X is the initial state of region 0 and state Y is the initial state of region 1. Both state A and state Y have a custom reaction for event E. State Y execute some computation based on event E while state A simply keeps track of how many times the event E is triggered. State A discard the event at the end of the custom reaction, while state Y forward it (the goal would be to forward it to the state A). >From the old post I think I have understood how the statechart library works and why the state Y never receives the event E. I guess that in my case state X is chosen as first state to process event E. Given that X is not interested in event E, the event is forwarded to state A, which process it and discard it. I see few possible solutions (with drawbacks) but I would like to know how this problem should be addressed. 1) I could do the counting directly in the state Y and remove the custom reaction to E from state A. This would work, however if tomorrow I will define a third state Z interested in E, I would have to duplicate the event counting code, which would work only if I assume that the Z and Y are not active at the same time (otherwise the event would be counted twice). 2) I could define an event that is listened only by state A and is triggered by the state Y after processing E. This doesn't seem really elegant and if multiple states are interested in E I have to be careful to not count the event twice. -- View this message in context: http://boost.2283326.n4.nabble.com/statechart-Events-forwarding-and-orthogo… Sent from the Boost - Users mailing list archive at Nabble.com.

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[variant] Possible regression from 1.55 to 1.58
by Mario Lang 12 Aug '15

12 Aug '15

Hi. I just upgraded my Boost from 1.55 to 1.58. My project doesn't build anymore, it fails on the following pattern, which used to work with 1.55: ---<snip>--- #include <algorithm> #include <boost/variant.hpp> #include <string> #include <iostream> #include <vector> struct visitor : boost::static_visitor<std::ostream &> { result_type operator() (int) { return std::cout; } result_type operator() (std::string) const { return std::cout; } }; int main() { std::vector< boost::variant<int, std::string> > v; visitor vis; foreach(v.begin(), v.end(), boost::apply_visitor(vis)); return 0; } ---<snip>--- The example is a bit silly, since foreach discards the return value of apply_visitor anyway. So my solution was to change the visitor to define result_type as void. This works. However, I am wondering why delayed_visitor does no longer work in this situation? Is it because I am trying to return a reference? -- CYa, ⡍⠁⠗⠊⠕

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Problem accessing boost trac
by Leo Carreon 12 Aug '15

12 Aug '15

Hi Boosters, Sorry to be posting this here but I’m trying to access boost trac and I’m getting a certificate error. Does anyone know how to resolve this issue? Regards, Leo

2 1

[intrusive_ptr] Strange ternary op behavior with MSVC14
by TONGARI J 12 Aug '15

12 Aug '15

Hi, I found a strange bug while debugging: This is the minimal example that shows the problem: (the nullptr will be some other meaningful thing in real case) ```c++ #include <iostream> #include <boost/smart_ptr/intrusive_ptr.hpp> #include <boost/smart_ptr/intrusive_ref_counter.hpp> template<class T> struct wrapper { wrapper() = default; wrapper(boost::intrusive_ptr<T> const& p) : _p(p) {} boost::intrusive_ptr<T> const& get_ptr() const { #if 0 // This is OK. if (_p) return _p; return nullptr; #else // Strange behavior. return _p ? _p : nullptr; #endif } private: boost::intrusive_ptr<T> _p; }; struct W : boost::intrusive_ref_counter<W> { }; template<class T1, class T2> inline void test(wrapper<T1> const& s1, wrapper<T2> const& s2) { auto tup = std::make_tuple(s1.get_ptr(), s2.get_ptr()); std::cout << 0 << ":" << (void*)std::get<0>(tup).get() << "\n"; std::cout << 1 << ":" << (void*)std::get<1>(tup).get() << "\n"; } int main() { wrapper<W> a(new W), b(new W); test(a, b); return 0; } ``` If compiled with MSVC14, you'll see the 2 addresses are the same while they shouldn't. If if-stmt is used instead, the problem won't be shown. I also replaced intrusive_ptr with std::shared_ptr and the problem isn't shown as well. The same code works well with g++. It seems intrusive_ptr & MSVC14 specific but I can't reason about... Any idea?

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[Boost.ASIO] [asio] Scaling TCP Server
by Sarvagya Pant 11 Aug '15

11 Aug '15

I have created a TCP server that can receive two types of message from client. 1. "Heartbeat" : If this is found and "first_fetch" is 1, send some config in Json format else send {"config_changed" : "true"} 2. "Message" : If this is found, send {"success" : "true"} The async server is here => https://gist.github.com/mesarvagya/a73f2428417cb10336ef and the client is given here => https://gist.github.com/mesarvagya/90d764c749d18d9c5184 While both works fine, but the server is slower than expected. If one sees, I have used ~3kb message in client. When the client and server are connected, I did a preliminary benchmarking and the result were as follows: 1. For 50K messages, the time was 6 seconds. 2. For 100K messages, the time was 11 seconds. 3. For 200K messages, the time was 36 seconds. 3. For 500K messages, the time was 82 seconds 3. For 1million messages, the time was 174 seconds. The server is not working as expected. Currently it works at ~6K message/seconds in localhost. I would like to optimize the current server to receive at-least 100K messages per second. How should I begin with optimizing the server code? Is it possible to receive such high message/seconds in boost.ASIO and if so, how should I approach with the server design? -- *Sarvagya Pant* *Kathmandu, Nepal* *+9779803468257*

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building boost 1.54 thread
by W. Miah 11 Aug '15

11 Aug '15

Hello, I am having trouble building the threaded version of boost (version 1.54). I require version 1.54 only. I am getting the below error message. Any help will be greatly appreciated. Regards, Wadud. [root@bengal boost_1_54_0]# g++ --version g++ (GCC) 4.9.2 20150212 (Red Hat 4.9.2-6) Copyright (C) 2014 Free Software Foundation, Inc. [root@bengal boost_1_54_0]# ./bootstrap.sh --prefix=/usr/local/boost-1.54 --with-libraries=thread Building Boost.Build engine with toolset gcc... tools/build/v2/engine/bin.linuxx86_64/b2 Unicode/ICU support for Boost.Regex?... /usr Generating Boost.Build configuration in project-config.jam... Bootstrapping is done. To build, run: ./b2 To adjust configuration, edit 'project-config.jam'. Further information: - Command line help: ./b2 --help - Getting started guide: http://www.boost.org/more/getting_started/unix-variants.html - Boost.Build documentation: http://www.boost.org/boost-build2/doc/html/index.html [root@bengal boost_1_54_0]# ./b2 install Component configuration: - atomic : not building - chrono : not building - context : not building - coroutine : not building - date_time : not building - exception : not building - filesystem : not building - graph : not building - graph_parallel : not building - iostreams : not building - locale : not building - log : not building - math : not building - mpi : not building - program_options : not building - python : not building - random : not building - regex : not building - serialization : not building - signals : not building - system : not building - test : not building - thread : building - timer : not building - wave : not building ...patience... ...patience... ...found 21612 targets... ...updating 38 targets... common.mkdir bin.v2 common.mkdir bin.v2/libs common.mkdir bin.v2/libs/system common.mkdir bin.v2/libs/system/build common.mkdir bin.v2/libs/system/build/gcc-4.9.2 common.mkdir bin.v2/libs/system/build/gcc-4.9.2/release common.mkdir bin.v2/libs/system/build/gcc-4.9.2/release/threading-multi gcc.compile.c++ bin.v2/libs/system/build/gcc-4.9.2/release/threading-multi/error_code.o In file included from ./boost/system/error_code.hpp:15:0, from libs/system/src/error_code.cpp:19: ./boost/cstdint.hpp:300:49: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ ./boost/cstdint.hpp:300:123: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ In file included from ./boost/system/error_code.hpp:15:0, from libs/system/src/error_code.cpp:19: ./boost/cstdint.hpp:300:195: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ gcc.link.dll bin.v2/libs/system/build/gcc-4.9.2/release/threading-multi/libboost_system.so.1.54.0 common.copy /usr/local/boost-1.54/lib/libboost_system.so.1.54.0 ln-UNIX /usr/local/boost-1.54/lib/libboost_system.so common.mkdir bin.v2/libs/thread common.mkdir bin.v2/libs/thread/build common.mkdir bin.v2/libs/thread/build/gcc-4.9.2 common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/thread.o In file included from ./boost/bind/bind.hpp:29:0, from ./boost/bind.hpp:22, from ./boost/thread/detail/thread.hpp:29, from ./boost/thread/thread_only.hpp:22, from libs/thread/src/pthread/thread.cpp:11: ./boost/bind/arg.hpp: In constructor ‘boost::arg<I>::arg(const T&)’: ./boost/bind/arg.hpp:37:22: warning: typedef ‘T_must_be_placeholder’ locally defined but not used [-Wunused-local-typedefs] typedef char T_must_be_placeholder[ I == is_placeholder<T>::value? 1: -1 ]; ^ In file included from ./boost/atomic.hpp:12:0, from ./boost/thread/pthread/once_atomic.hpp:20, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/thread.cpp:17: ./boost/atomic/atomic.hpp: At global scope: ./boost/atomic/atomic.hpp:202:16: error: ‘uintptr_t’ was not declared in this scope typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:25: error: template argument 1 is invalid typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:43: error: invalid type in declaration before ‘;’ token typedef atomic<uintptr_t> atomic_uintptr_t; ^ In file included from ./boost/system/system_error.hpp:14:0, from ./boost/thread/exceptions.hpp:22, from ./boost/thread/pthread/thread_data.hpp:10, from ./boost/thread/thread_only.hpp:17, from libs/thread/src/pthread/thread.cpp:11: ./boost/system/error_code.hpp:222:36: warning: ‘boost::system::posix_category’ defined but not used [-Wunused-variable] static const error_category & posix_category = generic_category(); ^ ./boost/system/error_code.hpp:223:36: warning: ‘boost::system::errno_ecat’ defined but not used [-Wunused-variable] static const error_category & errno_ecat = generic_category(); ^ ./boost/system/error_code.hpp:224:36: warning: ‘boost::system::native_ecat’ defined but not used [-Wunused-variable] static const error_category & native_ecat = system_category(); ^ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pedantic -pthread -fPIC -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DNDEBUG -I"." -c -o "bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/thread.o" "libs/thread/src/pthread/thread.cpp" ...failed gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/thread.o... gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/once.o In file included from ./boost/bind/bind.hpp:29:0, from ./boost/bind.hpp:22, from ./boost/thread/pthread/once_atomic.hpp:19, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/./once_atomic.cpp:9, from libs/thread/src/pthread/once.cpp:8: ./boost/bind/arg.hpp: In constructor ‘boost::arg<I>::arg(const T&)’: ./boost/bind/arg.hpp:37:22: warning: typedef ‘T_must_be_placeholder’ locally defined but not used [-Wunused-local-typedefs] typedef char T_must_be_placeholder[ I == is_placeholder<T>::value? 1: -1 ]; ^ In file included from ./boost/atomic.hpp:12:0, from ./boost/thread/pthread/once_atomic.hpp:20, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/./once_atomic.cpp:9, from libs/thread/src/pthread/once.cpp:8: ./boost/atomic/atomic.hpp: At global scope: ./boost/atomic/atomic.hpp:202:16: error: ‘uintptr_t’ was not declared in this scope typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:25: error: template argument 1 is invalid typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:43: error: invalid type in declaration before ‘;’ token typedef atomic<uintptr_t> atomic_uintptr_t; ^ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pedantic -pthread -fPIC -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DNDEBUG -I"." -c -o "bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/once.o" "libs/thread/src/pthread/once.cpp" ...failed gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/pthread/once.o... gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi/future.o ...skipped <pbin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi>libboost_thread.so.1.54.0 for lack of <pbin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi>pthread/thread.o... ...skipped <p/usr/local/boost-1.54/lib>libboost_thread.so.1.54.0 for lack of <pbin.v2/libs/thread/build/gcc-4.9.2/release/threading-multi>libboost_thread.so.1.54.0... ...skipped <p/usr/local/boost-1.54/lib>libboost_thread.so for lack of <p/usr/local/boost-1.54/lib>libboost_thread.so.1.54.0... common.mkdir bin.v2/libs/system/build/gcc-4.9.2/release/link-static common.mkdir bin.v2/libs/system/build/gcc-4.9.2/release/link-static/threading-multi gcc.compile.c++ bin.v2/libs/system/build/gcc-4.9.2/release/link-static/threading-multi/error_code.o In file included from ./boost/system/error_code.hpp:15:0, from libs/system/src/error_code.cpp:19: ./boost/cstdint.hpp:300:49: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ ./boost/cstdint.hpp:300:123: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ In file included from ./boost/system/error_code.hpp:15:0, from libs/system/src/error_code.cpp:19: ./boost/cstdint.hpp:300:195: warning: use of C++11 long long integer constant [-Wlong-long] # elif (defined(ULLONG_MAX) && ULLONG_MAX == 18446744073709551615ULL) || (defined(ULONG_LONG_MAX) && ULONG_LONG_MAX == 18446744073709551615ULL) || (defined(ULONGLONG_MAX) && ULONGLONG_MAX == 18446744073709551615ULL) ^ gcc.archive bin.v2/libs/system/build/gcc-4.9.2/release/link-static/threading-multi/libboost_system.a common.copy /usr/local/boost-1.54/lib/libboost_system.a common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release/link-static common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi common.mkdir bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/thread.o In file included from ./boost/bind/bind.hpp:29:0, from ./boost/bind.hpp:22, from ./boost/thread/detail/thread.hpp:29, from ./boost/thread/thread_only.hpp:22, from libs/thread/src/pthread/thread.cpp:11: ./boost/bind/arg.hpp: In constructor ‘boost::arg<I>::arg(const T&)’: ./boost/bind/arg.hpp:37:22: warning: typedef ‘T_must_be_placeholder’ locally defined but not used [-Wunused-local-typedefs] typedef char T_must_be_placeholder[ I == is_placeholder<T>::value? 1: -1 ]; ^ In file included from ./boost/atomic.hpp:12:0, from ./boost/thread/pthread/once_atomic.hpp:20, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/thread.cpp:17: ./boost/atomic/atomic.hpp: At global scope: ./boost/atomic/atomic.hpp:202:16: error: ‘uintptr_t’ was not declared in this scope typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:25: error: template argument 1 is invalid typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:43: error: invalid type in declaration before ‘;’ token typedef atomic<uintptr_t> atomic_uintptr_t; ^ In file included from ./boost/system/system_error.hpp:14:0, from ./boost/thread/exceptions.hpp:22, from ./boost/thread/pthread/thread_data.hpp:10, from ./boost/thread/thread_only.hpp:17, from libs/thread/src/pthread/thread.cpp:11: ./boost/system/error_code.hpp:222:36: warning: ‘boost::system::posix_category’ defined but not used [-Wunused-variable] static const error_category & posix_category = generic_category(); ^ ./boost/system/error_code.hpp:223:36: warning: ‘boost::system::errno_ecat’ defined but not used [-Wunused-variable] static const error_category & errno_ecat = generic_category(); ^ ./boost/system/error_code.hpp:224:36: warning: ‘boost::system::native_ecat’ defined but not used [-Wunused-variable] static const error_category & native_ecat = system_category(); ^ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pedantic -pthread -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_STATIC_LINK=1 -DBOOST_THREAD_BUILD_LIB=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DNDEBUG -I"." -c -o "bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/thread.o" "libs/thread/src/pthread/thread.cpp" ...failed gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/thread.o... gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/once.o In file included from ./boost/bind/bind.hpp:29:0, from ./boost/bind.hpp:22, from ./boost/thread/pthread/once_atomic.hpp:19, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/./once_atomic.cpp:9, from libs/thread/src/pthread/once.cpp:8: ./boost/bind/arg.hpp: In constructor ‘boost::arg<I>::arg(const T&)’: ./boost/bind/arg.hpp:37:22: warning: typedef ‘T_must_be_placeholder’ locally defined but not used [-Wunused-local-typedefs] typedef char T_must_be_placeholder[ I == is_placeholder<T>::value? 1: -1 ]; ^ In file included from ./boost/atomic.hpp:12:0, from ./boost/thread/pthread/once_atomic.hpp:20, from ./boost/thread/once.hpp:20, from libs/thread/src/pthread/./once_atomic.cpp:9, from libs/thread/src/pthread/once.cpp:8: ./boost/atomic/atomic.hpp: At global scope: ./boost/atomic/atomic.hpp:202:16: error: ‘uintptr_t’ was not declared in this scope typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:25: error: template argument 1 is invalid typedef atomic<uintptr_t> atomic_uintptr_t; ^ ./boost/atomic/atomic.hpp:202:43: error: invalid type in declaration before ‘;’ token typedef atomic<uintptr_t> atomic_uintptr_t; ^ "g++" -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pedantic -pthread -Wextra -Wno-long-long -Wno-variadic-macros -Wunused-function -pedantic -DBOOST_ALL_NO_LIB=1 -DBOOST_SYSTEM_STATIC_LINK=1 -DBOOST_THREAD_BUILD_LIB=1 -DBOOST_THREAD_DONT_USE_CHRONO -DBOOST_THREAD_POSIX -DNDEBUG -I"." -c -o "bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/once.o" "libs/thread/src/pthread/once.cpp" ...failed gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/pthread/once.o... gcc.compile.c++ bin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi/future.o ...skipped <pbin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi>libboost_thread.a(clean) for lack of <pbin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi>pthread/thread.o... ...skipped <pbin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi>libboost_thread.a for lack of <pbin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi>pthread/thread.o... ...skipped <p/usr/local/boost-1.54/lib>libboost_thread.a for lack of <pbin.v2/libs/thread/build/gcc-4.9.2/release/link-static/threading-multi>libboost_thread.a... ...failed updating 4 targets... ...skipped 6 targets... ...updated 28 targets... [root@bengal boost_1_54_0]#

1 0

Reusing expressions::stream
by Florian Lindner 11 Aug '15

11 Aug '15

Hello, with boost log I have: using namespace boost::log; add_file_log ( "sample.log", keywords::format = ( expressions::stream << expressions::format_date_time<boost::posix_time::ptime>("TimeStamp", "%H:%M:%S") << " [Rank: "<< expressions::attr<int>("Rank") << "]" << ": " << expressions::message ) ); which works fine. Now that may be a maximum stupid questions. But when I want to reuse the format expressions for other uses, e.g. another sink, how can I do that? i.e. how to declare and use a variable that holds that expressions? :-/ Thanks, Florian

1 0

Dijkstra Algorithm Implementation Details
by Mayank Bakshi 11 Aug '15

11 Aug '15

2 1

Install header-only libraries
by Gonzalo BG 11 Aug '15

11 Aug '15

I'm trying to find in the docs what is the right way to install only the header-only libraries from a boost distribution without any luck. That is, I want to install everything that can be installed without having to compile anything. Is there an argument for `bootstrap.sh` or `b2` that does this? Best regards, Gonzalo

2 3

[units] Dimensionless? expecting length+length
by Michael Powell 11 Aug '15

11 Aug '15

Hello, I am working on some trajectory calculations, and having a strange compiler error. First, great that I should get a compiler error at all! Second, what am I missing? quantity<acceleration> g() { static const auto gValue = static_cast<double>(9.812); static const auto metersPerSecondPerSecond = meters / second / second; static const quantity<acceleration> g = gValue*metersPerSecondPerSecond; return g; } double Class1::CalculateZeta(double timeMilliseconds, double heightMeters) { static const auto two = static_cast<double>(2); static const auto milliseconds = milli*seconds; const auto t = timeMilliseconds*milliseconds; const auto h = heightMeters*meters; const auto g_ = g(); auto result = -(g_ / two)*(t*t) + h; return result.value(); } Just if I did the dimensional analysis, I might expect the time components (i.e. T^2) to cancel themselves out, which should leave me with length+length, no? This is exposed via a C++ CLR (VS2013), but the Boost.Units are done internally. What am I missing here? I need to normalize the units, say to meters, etc? Best regards, Michael Powell Errors: Error 4 error C2676: binary '+' : 'boost::units::quantity<boost::units::unit<boost::units::list<boost::units::dim<Derived,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::heterogeneous_system<boost::units::heterogeneous_system_impl<boost::units::list<boost::units::heterogeneous_system_dim<boost::units::si::meter_base_unit,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::list<boost::units::dim<Derived,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::list<boost::units::scale_list_dim<Scale>,boost::units::dimensionless_type>>>,void>,double>' does not define this operator or a conversion to a type acceptable to the predefined operator I:\Source\Spikes\Kingdom.Physics\src\Kingdom.Physics.Calculators\Class1.cpp 43 1 Kingdom.Physics.Calculators Error 2 error C2784: 'add_typeof_helper<boost::units::unit<Dim1,System1,void>,boost::units::unit<Dim2,System2,void>>::type boost::units::operator +(const boost::units::unit<Dim1,System1,void> &,const boost::units::unit<Dim2,System2,void> &)' : could not deduce template argument for 'const boost::units::unit<Dim1,System1,void> &' from 'boost::units::quantity<boost::units::unit<boost::units::list<boost::units::dim<Derived,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::heterogeneous_system<boost::units::heterogeneous_system_impl<boost::units::list<boost::units::heterogeneous_system_dim<boost::units::si::meter_base_unit,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::list<boost::units::dim<Derived,boost::units::static_rational<1,1>>,boost::units::dimensionless_type>,boost::units::list<boost::units::scale_list_dim<Scale>,boost::units::dimensionless_type>>>,void>,double>' I:\Source\Spikes\Kingdom.Physics\src\Kingdom.Physics.Calculators\Class1.cpp 43 1 Kingdom.Physics.Calculators Error 3 error C2893: Failed to specialize function template 'add_typeof_helper<boost::units::quantity<Unit1,X>,boost::units::quantity<Unit2,Y>>::type boost::units::operator +(const boost::units::quantity<Unit1,X> &,const boost::units::quantity<Unit2,Y> &)' I:\Source\Spikes\Kingdom.Physics\src\Kingdom.Physics.Calculators\Class1.cpp 43 1 Kingdom.Physics.Calculators 5 IntelliSense: no operator "+" matches these operands operand types are: boost::units::quantity<boost::units::unit<boost::units::list<boost::units::dim<boost::units::length_base_dimension, boost::units::static_rational<1L, 1L>>, boost::units::dimensionless_type>, boost::units::heterogeneous_system<boost::units::heterogeneous_system_impl<boost::units::list<boost::units::heterogeneous_system_dim<boost::units::si::meter_base_unit, boost::units::static_rational<1L, 1L>>, boost::units::dimensionless_type>, boost::units::list<boost::units::dim<boost::units::length_base_dimension, boost::units::static_rational<1L, 1L>>, boost::units::dimensionless_type>, boost::units::list<boost::units::scale_list_dim<boost::units::scale<10L, boost::units::static_rational<-6L, 1L>>>, boost::units::dimensionless_type>>>, void>, double> + const boost::units::quantity<boost::units::unit<boost::units::length_dimension, boost::units::si::system, void>, double> i:\Source\Spikes\Kingdom.Physics\src\Kingdom.Physics.Calculators\Class1.cpp 43 49 Kingdom.Physics.Calculators

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