April 2013 - Boost-users - lists.preview.boost.org

[Test] Where to learn about boost::itest::mock_object?
by Mateusz Loskot 20 Jan '14

20 Jan '14

Hi, I'm looking for a simple mocking library to use together with Boost.Test. There is Turtle (aka Boost.Mock) and googlemock. During retrospection of the big thread on Boost.Test future [1], I found this curious post by Gennadiy [2] about mock_object. I had no idea such facility lives in Boost.Test and it looks it's been there for very long time. I can't find any documentation about mock_oboject, only a couple of examples. So, I have a few questions: Is the mock_object an internal feature or is it dedicated (and ready) to use by Boost.Test users? What are basic features of this mocking facility? How does it compare to Turtle or googlemock? [1] http://thread.gmane.org/gmane.comp.lib.boost.devel/234297 [2] http://thread.gmane.org/gmane.comp.lib.boost.devel/234297/focus=234621 [3] find /home/mloskot/dev/boost/_svn/trunk/libs/test -type f | xargs grep mock_object Best regards, -- Mateusz Loskot, http://mateusz.loskot.net

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Does Boost.Test cover 'golden file approach'?
by Journeyer J. Joh 13 Jan '14

13 Jan '14

Hello, I know almost nothing about 'golden file approach'. http://weblogs.java.net/blog/alexeyp/archive/2007/02/testing_command.html >From this blog, you can find the term 'golden file approach'. I want to know if Boost.Test cover this kind of testing. Can I implement 'golden file approach' with Boost.Test? If so please provide me more information about it. Thank you very much. ---------------------------------------- Journeyer J. Joh o o s a p r o g r a m m e r a t g m a i l d o t c o m ----------------------------------------

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[boost.test] How to register custom exception for auto test?
by Jörg Becker 13 Jan '14

13 Jan '14

Hi, I'm using the test library of boost 1.49.0 for my unit tests. It works fine so fare, but if my program throws an error, I get the default error message unknown location(0): fatal error in "excption1_test": unknown type, witch hides the original error message. I tried to register an error translator, but without success. Here is what I tried (modified test/test/custom_exception_test.cpp to use auto test with global fixture): #define BOOST_TEST_MODULE "boost test custom_exception_test" #include <boost/test/unit_test.hpp> #include <boost/test/unit_test_monitor.hpp> using namespace boost::unit_test; BOOST_AUTO_TEST_SUITE( custom_exception_testsuite ) struct my_exception1 { explicit my_exception1( int res_code ) : m_res_code( res_code ) {} int m_res_code; }; void throw_my_exception1() { throw my_exception1( 12 ); } void my_exception1_translator( my_exception1 ) { BOOST_TEST_MESSAGE( "Caught my_exception1" ); } class my_config { public: my_config () { unit_test_monitor.register_exception_translator<my_exception1>( &my_exception1_translator ); } }; BOOST_GLOBAL_FIXTURE( my_config ) BOOST_AUTO_TEST_CASE( excption1_test ) { throw_my_exception1(); } BOOST_AUTO_TEST_SUITE_END() Can anybody tell me what I'm missing? Thanks, Jörg

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using boost with net-snmp
by moshe levi 12 Sep '13

12 Sep '13

I wrote an example on how to integrate net-snmp with boost. please checkout http://blog-moshe.blogspot.co.il/

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[BGL] Having a cost function as weight map
by Maxime van Noppen 06 Sep '13

06 Sep '13

Hi, I can't find how to do this pretty basic thing : having a function instead of a field to compute the cost of edges for various path finding algorithms. I couldn't find the answer in the documentation and Google was of no help. Did I miss something obvious ? Example : ------------------- #include <boost/graph/dijkstra_shortest_paths.hpp> #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> struct my_edge { double cost() const { return cost_ * 2; } double cost_; }; struct my_node { }; int main() { typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::directedS, my_node, my_edge > graph_t; typedef boost::graph_traits<graph_t>::vertex_descriptor vertex_t; graph_t graph; vertex_t v /*= ... */; using boost::weight_map; // Works : boost::dijkstra_shortest_paths(graph, v, weight_map(boost::get(&my_edge::cost_, graph))); // Doesn't compile : //boost::dijkstra_shortest_paths(graph, v, // weight_map(boost::get(&my_edge::cost, graph))); } ------------------- Thanks ! -- Maxime

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Identify cycles in a undirected graph
by NsPx 20 Aug '13

20 Aug '13

Hi all, I use undirected_dfs to detect all cycles in a undirected graph. I detect a cycle with DFSVisitor.back_edge(e,g) but how can I get the list of vertices defining this cycle ? Thanks by advance

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[exception] exception_ptr missing virtual base parameters
by Michael Caisse 13 Jul '13

13 Jul '13

The basic problem I'm experiencing is that getting an exception_ptr results inherited parameters getting lost when virtual inheritance is used. The code below demonstrates a simple example. "bar" is lost in the print. Changing derived_except to be: struct derived_except : base_except { int i; }; will cause the inherited values to be copied into the exception_ptr; however, this has all the standard problems associated that come with not using virtual inheritance. This looks like a bug to me. The C++11 equivalent behaves has expected and inherited values are maintained in the exception_ptr. Any thoughts? michael -------------- boost::exception_ptr version -------------- #include <boost/exception/all.hpp> #include <string> #include <iostream> struct base_except { std::string s; }; struct derived_except : virtual base_except { int i; }; int main() { derived_except e; e.i = 8; e.s = "bar"; boost::exception_ptr ptr = boost::copy_exception(e); try { boost::rethrow_exception(ptr); } catch(derived_except & e) { std::cout << "derived_except: " << e.s << " " << e.i << std::endl; } catch(...) {} return 0; } -------------- c++11 version --------------------- #include <exception> #include <string> #include <iostream> struct base_except { std::string s; }; struct derived_except : virtual base_except { int i; }; int main() { derived_except e; e.i = 8; e.s = "bar"; std::exception_ptr ptr = std::make_exception_ptr(e); try { std::rethrow_exception(ptr); } catch(derived_except & e) { std::cout << "derived_except: " << e.s << " " << e.i << std::endl; } catch(...) {} return 0; } -- Michael Caisse ciere consulting ciere.com

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ASIO: Problem with building boost 1.53 ASIO examples under cygwin
by mschulze＠ivs.cs.ovgu.de 27 Jun '13

27 Jun '13

Hi all, I tried building boost 1.53 ASIO examples under cygwin and it didn't worked with bjam or b2 respectively. Then I used "bjam -n" to get the invoked commands in order to further track down the issue. I end up with the following command to compile an example "g++" -ftemplate-depth-128 -O0 -fno-inline -Wall -g -mthreads -DBOOST_ALL_NO_LIB=1 -DBOOST_CHRONO_DYN_LINK=1 -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_SYSTEM_NO_DEPRECATED -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_POSIX -DBOOST_THREAD_USE_DLL=1 -I"../../../.." -o "blocking_udp_echo_server" "blocking_udp_echo_server.cpp" -D__USE_W32_SOCKETS -D_WIN32_WINNT=0x0501 ../../../../bin.v2/libs/thread/build/gcc-4.5.3/release/link-static/threading-multi/libboost_thread.a ../../../../bin.v2/libs/system/build/gcc-4.5.3/release/link-static/threading-multi/libboost_system.a -lws2_32 -lmswsock and I got the following errors: In file included from ../../../../boost/asio/detail/impl/posix_tss_ptr.ipp:24:0, from ../../../../boost/asio/detail/posix_tss_ptr.hpp:77, from ../../../../boost/asio/detail/tss_ptr.hpp:27, from ../../../../boost/asio/detail/call_stack.hpp:20, from ../../../../boost/asio/impl/handler_alloc_hook.ipp:19, from ../../../../boost/asio/handler_alloc_hook.hpp:80, from ../../../../boost/asio/detail/handler_alloc_helpers.hpp:22, from ../../../../boost/asio/detail/bind_handler.hpp:19, from ../../../../boost/asio/detail/wrapped_handler.hpp:18, from ../../../../boost/asio/io_service.hpp:24, from ../../../../boost/asio/basic_io_object.hpp:19, from ../../../../boost/asio/basic_socket.hpp:19, from ../../../../boost/asio/basic_datagram_socket.hpp:20, from ../../../../boost/asio.hpp:20, from blocking_udp_echo_server.cpp:13: ../../../../boost/asio/error.hpp:77:17: error: a function call cannot appear in a constant-expression ../../../../boost/asio/error.hpp:130:15: error: a function call cannot appear in a constant-expression ../../../../boost/asio/error.hpp:135:19: error: a function call cannot appear in a constant-expression ../../../../boost/asio/error.hpp:149:23: error: a function call cannot appear in a constant-expression ../../../../boost/asio/error.hpp:163:15: error: a function call cannot appear in a constant-expression ../../../../boost/asio/error.hpp:244:45: warning: boost::asio::error::system_category defined but not used ../../../../boost/asio/error.hpp:246:45: warning: boost::asio::error::netdb_category defined but not used ../../../../boost/asio/error.hpp:248:45: warning: boost::asio::error::addrinfo_category defined but not used ../../../../boost/asio/error.hpp:250:45: warning: boost::asio::error::misc_category defined but not used ../../../../boost/asio/detail/winsock_init.hpp:78:30: warning: boost::asio::detail::winsock_init_instance defined but not used The error messages boils down to the use of "__MSABI_LONG(x)" within an enumeration definition. __MSABI_LONG is a macro that has to be resolved during the cpp run but isn't but it seems not to be known at this point. I also tested the boost version 1.52 and there are none of these issues and it worked like it is intended. Best regards, Michael

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[thread] synchronized_value: value and move semantics
by Vicente J. Botet Escriba 08 Jun '13

08 Jun '13

Hi, boost::synchronized_value (not released yet [1][2][3]) is based on [4]. See below part of this paper adapted to the Boost.Thread interface. Currently boost::synchronized_value is in addition Copyable and Swappable. I was wondering if it is worth adding value and move semantics to synchronized_value. Making it EqualityComparable, LessThanComparable and Movable if the underlying type satisfy these requirements will allow to store them on a Boost.Container/C++11 container. Do you see something completely wrong with this addition? Has some of you had a need for this? Could you share the context? Best, Vicente [1] https://svn.boost.org/svn/boost/trunk/boost/thread/synchronized_value.hpp [2] https://svn.boost.org/svn/boost/trunk/libs/thread/example/synchronized_valu… [3] https://svn.boost.org/svn/boost/trunk/libs/thread/example/synchronized_pers… [4] "Enforcing Correct Mutex Usage with Synchronized Values" by Anthony Williams http://www.drdobbs.com/cpp/enforcing-correct-mutex-usage-with-synch/2252002… ------------- [section The Problem with Mutexes] The key problem with protecting shared data with a mutex is that there is no easy way to associate the mutex with the data. It is thus relatively easy to accidentally write code that fails to lock the right mutex - or even locks the wrong mutex - and the compiler will not help you. std::mutex m1; int value1; std::mutex m2; int value2; int readValue1() { boost::lock_guard<boost::mutex> lk(m1); return value1; } int readValue2() { boost::lock_guard<boost::mutex> lk(m1); // oops: wrong mutex return value2; } Moreover, managing the mutex lock also clutters the source code, making it harder to see what is really going on. The use of synchronized_value solves both these problems - the mutex is intimately tied to the value, so you cannot access it without a lock, and yet access semantics are still straightforward. For simple accesses, synchronized_value behaves like a pointer-to-T; for example: boost::synchronized_value<std::string> value3; std::string readValue3() { return *value3; } void setValue3(std::string const& newVal) { *value3=newVal; } void appendToValue3(std::string const& extra) { value3->append(extra); } Both forms of pointer dereference return a proxy object rather than a real reference, to ensure that the lock on the mutex is held across the assignment or method call, but this is transparent to the user. [endsect] [/The Problem with Mutexes] [section Beyond Simple Accesses] The pointer-like semantics work very well for simple accesses such as assignment and calls to member functions. However, sometimes you need to perform an operation that requires multiple accesses under protection of the same lock, and that's what the synchronize() method provides. By calling synchronize() you obtain an strict_lock_ptr object that holds a lock on the mutex protecting the data, and which can be used to access the protected data. The lock is held until the strict_lock_ptr object is destroyed, so you can safely perform multi-part operations. The strict_lock_ptr object also acts as a pointer-to-T, just like synchronized_value does, but this time the lock is already held. For example, the following function adds a trailing slash to a path held in a synchronized_value. The use of the strict_lock_ptr object ensures that the string hasn't changed in between the query and the update. void addTrailingSlashIfMissing(boost::synchronized_value<std::string> & path) { boost::strict_lock_ptr<std::string> u=path.synchronize(); if(u->empty() || (*u->rbegin()!='/')) { *u+='/'; } } [endsect] [/Beyond Simple Accesses] [section Operations Across Multiple Objects] Though synchronized_value works very well for protecting a single object of type T, nothing that we've seen so far solves the problem of operations that require atomic access to multiple objects unless those objects can be combined within a single structure protected by a single mutex. One way to protect access to two synchronized_value objects is to construct a strict_lock_ptr for each object and use those to access the respective protected values; for instance: synchronized_value<std::queue<MessageType> > q1,q2; void transferMessage() { strict_lock_ptr<std::queue<MessageType> > u1 = q1.synchronize(); strict_lock_ptr<std::queue<MessageType> > u2 = q2.synchronize(); if(!u1->empty()) { u2->push_back(u1->front()); u1->pop_front(); } } This works well in some scenarios, but not all - if the same two objects are updated together in different sections of code then you need to take care to ensure that the strict_lock_ptr objects are constructed in the same sequence in all cases, otherwise you have the potential for deadlock. This is just the same as when acquiring any two mutexes. In order to be able to use the dead-lock free lock algorithms we need to use instead unique_lock_ptr, which is Lockable. synchronized_value<std::queue<MessageType> > q1,q2; void transferMessage() { unique_lock_ptr<std::queue<MessageType> > u1 = q1.unique_synchronize(boost::defer_lock); unique_lock_ptr<std::queue<MessageType> > u2 = q2.unique_synchronize(boost::defer_lock); boost::lock(u1,u2); // dead-lock free algorithm if(!u1->empty()) { u2->push_back(u1->front()); u1->pop_front(); } } [endsect] [/Operations Across Multiple Objects]

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Is boost::this_thread::sleep_for interruption point?
by Serg Gulko 23 May '13

23 May '13

Hello! According to documentation(v 1.50.0) call boost::this_thread::sleep_for can be interrupted. For some reason this functionality not works for me. Here is code sample: //Simple thread function void Test::worker(int delay) { try { boost::this_thread::sleep_for(boost::chrono::milliseconds(delay)); cout << "Doing some work" << endl; } catch (boost::thread_interrupted const& e) { cout << "INTERRUPTED" << endl; } } //Far in the code boost::thread workerThread(boost::bind(&Test::worker, this, 1200)); boost::this_thread::sleep(boost::posix_time::milliseconds(30)); workerThread.interrupt(); boost::this_thread::sleep(boost::posix_time::milliseconds(1500)); I always getting 'Doing some work'... -- View this message in context: http://boost.2283326.n4.nabble.com/Is-boost-this-thread-sleep-for-interrupt… Sent from the Boost - Users mailing list archive at Nabble.com.

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