February 2007 - Boost-users

Boost::Date_Time - Incr and Decr Operators
by Steve Johns 12 Feb '07

12 Feb '07

Getting started with Boost::Date_Time ... It seems that this is OK: greg_year y1(2000); y1 = y1 + 1; but this is not: greg_year y1(2000); y1++; I take it that the increment and decrement operators are not implemented for greg_year (or the corresponding month, day, etc. types). Is this just incidental to the current implmentation, or is there some particular architectural or domain reason why ++ and -- aren't in the mix? - Steve

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[signals] sandbox version status
by Timmo Stange 12 Feb '07

12 Feb '07

The modified version of Boost.Signals in the sandbox now compiles and passes the tests on my setup. Basic thread-safety is also in there, minus tracking and the combiner/signal-to-signal connection issues that have been discussed here recently. The thread-safe version will not support grouping and naming of slots, so there is a preprocessor flag "BOOST_SIGNALS_NO_LEGACY_SUPPORT" which changes the template signature of signalN. If defined, the Group and GroupCompare parameters are replaced with a ThreadingModel parameter (I chose to put it there and not after SlotFunction, but that may change). It defaults to signals::single_threaded which results in non-thread-safe behaviour. When signals::multi_threaded is given as an argument, the signal should be thread-safe. That is for now completely untested, though ;). As I was curious about the call performance, I ran a simple test, successively connecting up to 4 slots to the signal and calling it 10000 - 10000000 times. Here are the results: # Calls CVS SBL SBNS SBNM 1 10000 0.005 0.003 0.001 0.002 1 100000 0.057 0.037 0.019 0.025 1 1000000 0.582 0.362 0.209 0.269 1 10000000 5.882 3.659 2.073 2.668 2 10000 0.007 0.004 0.002 0.003 2 100000 0.075 0.044 0.027 0.031 2 1000000 0.769 0.461 0.269 0.322 2 10000000 7.668 4.535 2.744 3.274 3 10000 0.009 0.005 0.003 0.003 3 100000 0.095 0.054 0.035 0.038 3 1000000 0.964 0.555 0.360 0.411 3 10000000 9.643 5.538 3.525 4.010 4 10000 0.011 0.006 0.003 0.004 4 100000 0.114 0.061 0.038 0.044 4 1000000 1.155 0.641 0.419 0.451 4 10000000 11.482 6.378 4.124 4.519 CVS = The current CVS HEAD version. SBL = The sandbox version with legacy support (named slots). SBNS = The sandbox version without legacy support, single-threaded. SBNM = The sandbox version without legacy support, thread-safe. I used Visual C++ 2005 Express SP1 with /O2 optimization on an Athlon X2 3800+ for these tests. Results are in seconds. The comparison to the original CVS version is not quite fair, as I used dynamic linking there and static linking for the rest of the tests. I just did it to make sure my code was not significantly slower. The overhead for thread-safety does not grow with the number of connected slots, as I use a per-signal mutex and no per-slot locking. That looks good here, but I'm not yet sure it is the best solution in the long run. It would be nice to not block the entire signal for the whole time. As the new single-threaded implementation is somewhat faster than the one supporting named slots, I will add a signals::no_name type that can be used for the Group template argument when legacy support is enabled. That will result in the faster implementation being used without losing compatibility to existing code with grouped slots. Reports about problems with certain compilers and any kind of other input would be very appreciated. Don't judge too harshly on the code, I know it needs a lot of cleanup ;). Regards Timmo Stange

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Performance of object_pool
by 蹬三轮的 12 Feb '07

12 Feb '07

The most important reason to use a memory pool is performance. BUT object_pool doesn't! When I use object_pool to construct a lot of objects, the destroy method become very slow. And I found object_pool use ordered_free to free the memory, and it amortized O(N). It is a very serious problem, I hope it can be fixed in the next release. thanks.

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Compiling Example Code for Boost::Date_Time
by Steve Johns 11 Feb '07

11 Feb '07

Hi. I am new to Boost, and beginning with compiling example code for Boost::Date_Time. I've had success compiling the many examples given here: http://www.boost.org/doc/html/date_time/examples.html but the very first example given here: http://www.boost.org/doc/html/date_time/examples/general_usage_examples.html I cannot compile without errors. (Code given below) Changing week(1) to weeks(1) got me past the first hurdle, but still not home. The problem seems to have something to do with 'Sunday' not being of the correct type, but I'm not truly certain what is going on, hence this post ... As background, I'm using the MS VC++ 2005 compiler and Boost 1_33_1. This example fails compilation from both the IDE and the command line. I'd appreciate any insight into what would be needed to get this example to correctly compile and run. (And if there is a flaw in the example, I'd suggest that the docs be fixed to provide it in working form.) Thanks! - Steve __ using namespace boost::gregorian; date weekstart(2002,Feb,1); date weekend = weekstart + week(1); date d2 = d1 + days(5); date today = day_clock::local_day(); if (d2 >= today) {} //date comparison operators date_period thisWeek(d1,d2); if (thisWeek.contains(today)) {}//do something //iterate and print the week day_iterator itr(weekstart); while (itr <= weekend) { std::cout << (*itr) << std::endl; ++itr; } //input streaming std::stringstream ss("2004-Jan-1"); ss >> d3; //date generator functions date d5 = next_weekday(d4, Sunday); //calculate Sunday following d4 //US labor day is first Monday in Sept nth_day_of_the_week_in_month labor_day(nth_dow::first,Monday, Sep); //calculate a specific date for 2004 from functor date d6 = labor_day.get_date(2004);

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[signals] thread-safe default combiner
by Frank Mori Hess 11 Feb '07

11 Feb '07

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I'm noticing now that boost::last_value isn't thread-safe when used with a non-void return value, since a thread can't in general be sure the signal will have any slots connected to it when it is invoked. Would it be acceptable to make last_value throw an exception on the non-void, no slots case? Throwing an exception seems preferable to the dreaded "undefined behaviour". Or we could use a slightly modified default combiner with a different name. - -- Frank -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFFzKtr5vihyNWuA4URAtTdAKCfJQicTdVtf5qaab5M2PCndy6bowCggwKi DnFSpe3zg5DJsKfCsfnOh7Q= =Tppf -----END PGP SIGNATURE-----

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Does boost have something to support binary data streams?
by Michael Marcin 11 Feb '07

11 Feb '07

I commonly need to write and read binary data from files. The streams in the standard library are very tedious to use for such tasks. I'd like to be able to construct a stream thats loads a little endian binary data file and use it to write/read data with the insertion/extraction operators on big endian or little endian systems. Does anything like this exists? Thanks, Michael Marcin

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Error in compiling Boost thread example
by Meryl Silverburgh 11 Feb '07

11 Feb '07

Hi, I am trying to compile the boost thread that I found here: http://www-eleves-isia.cma.fr/documentation/BoostDoc/boost_1_29_0/libs/thre… But i get the following error: Can you please tell me what do i need to do to fix it? ./thread.o: In function `main':../thread.cpp:27: undefined reference to `boost::thread::thread(boost::function0<void, std::allocator<boost::function_base> > const&)' :../thread.cpp:28: undefined reference to `boost::thread::join()' :../thread.cpp:28: undefined reference to `boost::thread::~thread()' :../thread.cpp:28: undefined reference to `boost::thread::~thread()' ./thread.o: In function `thread_alarm::operator()()':../thread.cpp:11: undefined reference to `boost::xtime_get(boost::xtime*, int)' :../thread.cpp:14: undefined reference to `boost::thread::sleep(boost::xtime const&)' collect2: ld returned 1 exit status make: *** [sandbox] Error 1 make: Target `all' not remade because of errors. Build complete for project sandbox

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how to use boost to bind to an attribute?
by Meryl Silverburgh 10 Feb '07

10 Feb '07

Hi, I have code like this which sort a Rect, which compare value of getY(), like this: vector<Rect*> rl; ::sort(rl.begin(), rl.end(), bind(less < int >(), bind(&Rect::getY, _1), bind(&Rect::getY, _2))); how can I change it so that it compares with the 'y' attribute? like, rect1.y < rect2.y? Thank you.

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[property_map] bit vector as property map
by Sebastian Weber 10 Feb '07

10 Feb '07

Hello everybody! I'm using the property_map scheme to pass some data-structures to vistors of BGL-algorithms. So far I usually use a vector in the manner: std::vector<std::size_t> props(num_vertices(my_graph), 0) Then I do something like bfs_search(..., make_my_vistor(&props[0]), ...) which works ok and passes me a correct property_map into the visitor created by make_my_visitor. Within that visitor I can then do the usual stuff like put(the_props_map, vertex_id, someValue) At least that's how I understood, how the property_map concept works. However, if I use a bit-vector the above scheme breaks down to work: std::vector<bool> bit_props(num_vertices(my_graph), false) bfs_search(..., make_my_vistor(&bit_props[0]), ...) The compiler compiles these lines, but complains that a temprorary is passed as a reference to make_my_visitor and the code generated crashes. My system is a Ubununtu Edgy with boost 1.33.1 and g++ 4.1.2. Any ideas why this happens and what I can do here? Thanks a lot in advance. Greetings, Sebastian

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FW: Question about Boost.Test
by Ranji Raghavan 09 Feb '07

09 Feb '07

-----Original Message----- From: Ranji Raghavan [mailto:ranji.raghavan@openspirit.com] Sent: Friday, February 09, 2007 11:09 AM To: ''boost-users(a)lists.boost.org' Subject: FW: [Boost-users] Question about Boost.Test I am rookie as far as BOOST.TEST is concerned - I am trying to compile and link a simple BOOST.TEST program using VS 2005 (SEE EMAIL BELOW FOR STEPS). When I try and this simple plagiarized test program listed below, I get a bunch of LINKER errors - Error 1 error LNK2019: unresolved external symbol "void __cdecl boost::test_tools::tt_detail::check_impl(class boost::test_tools::predicate_result const &,class boost::basic_wrap_stringstream<char> &,class boost::unit_test::basic_cstring<char const >,unsigned int,enum boost::test_tools::tt_detail::tool_level,enum boost::test_tools::tt_detail::check_type,unsigned int,...)" (?check_impl@tt_detail@test_tools@boost@@YAXABVpredicate_result@23@AAV?$basi c_wrap_stringstream@D@3@V?$basic_cstring@$$CBD@unit_test@3@IW4tool_level@123 @W4check_type@123@IZZ) referenced in function "void __cdecl free_test_function(void)" (?free_test_function@@YAXXZ) NewTest.obj Error 2 error LNK2019: unresolved external symbol "public: void __thiscall boost::unit_test::test_suite::add(class boost::unit_test::test_unit *,unsigned long,unsigned int)" (?add@test_suite@unit_test@boost@@QAEXPAVtest_unit@23@KI@Z) referenced in function "class boost::unit_test::test_suite * __cdecl init_unit_test_suite(int,char * * const)" (?init_unit_test_suite@@YAPAVtest_suite@unit_test@boost@@HQAPAD@Z) NewTest.obj Etc etc ... May be I am missing something trivial that is causing this problem. Appreciate any help rendered.... Ranji -----Original Message----- From: Ranji Raghavan [mailto:ranji.raghavan@openspirit.com] Sent: Thursday, February 08, 2007 9:51 PM To: 'boost-users(a)lists.boost.org' Subject: RE: [Boost-users] Question about Boost.Test I have downloaded and built the BOOST libraries using VS2005 - I have pointed the VC++ directories INCLUDE files to the BOOST install directory and the Library files to the folder where the BOOST libraries were built to. But when I try even the simplest of test programs from one of the examples you had written - see below #include <boost/test/unit_test.hpp> using boost::unit_test_framework::test_suite; // most frequently you implement test cases as a free functions void free_test_function() { // reports 'error in "free_test_function": test 2 == 1 failed' BOOST_CHECK(2 == 1); // non-critical test => continue after failure } test_suite* init_unit_test_suite( int, char**) { test_suite* test= BOOST_TEST_SUITE( "Unit test example 1" ); // this example will pass cause we know ahead of time number of expected failures test->add( BOOST_TEST_CASE( &free_test_function ), 1 /* expected one error */ ); return test; } I receive LINK errors - any suggestions ? -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Gennadiy Rozental Sent: Wednesday, February 07, 2007 4:09 PM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Question about Boost.Test "Ranji Raghavan" <ranji.raghavan(a)openspirit.com> wrote in message news:000a01c74a28$df145f30$e90a0a0a@openspirit.com... > Actually, I am just looking into BOOST reading the documentation etc > Do you recommend any particular version of BOOST that I should install and > play with? I recommend you to use the latest version. Try 1.34 RC. > I am looking to define all the test data in XML files - maybe > 1000's of them - have a class that parses this XML file (some tests have > about 7-8 pieces of disparate primitive data types string, double, int > etc)and pass the array of class instances to a test method for repetitive > testing. If this is not pragmatic, could you recommend another way? Use BOOST_PARAM_TEST_CASE. It works differently in latest version then before. You will have less problems with parametrs object lifetime management. Let me know if you have any problems. Gennadiy _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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